WO1994000619A1 - Non-chromated oxide coating for aluminum substrates - Google Patents
Non-chromated oxide coating for aluminum substrates Download PDFInfo
- Publication number
- WO1994000619A1 WO1994000619A1 PCT/EP1993/001630 EP9301630W WO9400619A1 WO 1994000619 A1 WO1994000619 A1 WO 1994000619A1 EP 9301630 W EP9301630 W EP 9301630W WO 9400619 A1 WO9400619 A1 WO 9400619A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- cobalt
- solution
- substrate
- iii
- salt
- Prior art date
Links
- 239000000758 substrate Substances 0.000 title claims abstract description 85
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 37
- 238000000576 coating method Methods 0.000 title claims description 61
- 239000011248 coating agent Substances 0.000 title claims description 43
- 239000000243 solution Substances 0.000 claims abstract description 173
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 113
- 239000010941 cobalt Substances 0.000 claims abstract description 113
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 112
- 238000007739 conversion coating Methods 0.000 claims abstract description 100
- 238000000034 method Methods 0.000 claims abstract description 98
- 230000008569 process Effects 0.000 claims abstract description 92
- 238000006243 chemical reaction Methods 0.000 claims abstract description 68
- 229910052751 metal Inorganic materials 0.000 claims abstract description 56
- 239000002184 metal Substances 0.000 claims abstract description 56
- 238000005260 corrosion Methods 0.000 claims abstract description 54
- 230000007797 corrosion Effects 0.000 claims abstract description 54
- 239000003973 paint Substances 0.000 claims abstract description 34
- 150000007942 carboxylates Chemical group 0.000 claims abstract description 32
- 239000000126 substance Substances 0.000 claims abstract description 24
- UPWOEMHINGJHOB-UHFFFAOYSA-N oxo(oxocobaltiooxy)cobalt Chemical compound O=[Co]O[Co]=O UPWOEMHINGJHOB-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 16
- 229910000838 Al alloy Inorganic materials 0.000 claims abstract description 15
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 15
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 14
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 14
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 14
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 13
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 12
- 239000007864 aqueous solution Substances 0.000 claims abstract description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052593 corundum Inorganic materials 0.000 claims abstract description 9
- 229910001845 yogo sapphire Inorganic materials 0.000 claims abstract description 9
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical class [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910007567 Zn-Ni Inorganic materials 0.000 claims abstract description 4
- 229910007614 Zn—Ni Inorganic materials 0.000 claims abstract description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 4
- 230000001747 exhibiting effect Effects 0.000 claims abstract 7
- 150000003839 salts Chemical class 0.000 claims description 45
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical group CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 22
- 239000000203 mixture Substances 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 229910001868 water Inorganic materials 0.000 claims description 21
- 239000000080 wetting agent Substances 0.000 claims description 21
- 239000011734 sodium Substances 0.000 claims description 20
- 229940011182 cobalt acetate Drugs 0.000 claims description 19
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical group [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 19
- 239000011777 magnesium Substances 0.000 claims description 18
- 239000011575 calcium Substances 0.000 claims description 16
- -1 carboxylate salt Chemical class 0.000 claims description 15
- 239000011701 zinc Substances 0.000 claims description 14
- 239000011572 manganese Substances 0.000 claims description 11
- 229910052748 manganese Inorganic materials 0.000 claims description 10
- 239000011654 magnesium acetate Substances 0.000 claims description 8
- 239000001632 sodium acetate Substances 0.000 claims description 8
- 235000017281 sodium acetate Nutrition 0.000 claims description 8
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 7
- 150000001349 alkyl fluorides Chemical class 0.000 claims description 7
- 230000015572 biosynthetic process Effects 0.000 claims description 6
- 235000011285 magnesium acetate Nutrition 0.000 claims description 6
- 229940069446 magnesium acetate Drugs 0.000 claims description 6
- 239000001639 calcium acetate Substances 0.000 claims description 4
- 235000011092 calcium acetate Nutrition 0.000 claims description 4
- 229960005147 calcium acetate Drugs 0.000 claims description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 4
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- 229910001635 magnesium fluoride Inorganic materials 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims 1
- 229910000861 Mg alloy Inorganic materials 0.000 claims 1
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 claims 1
- 229960004249 sodium acetate Drugs 0.000 claims 1
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 abstract description 12
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 abstract description 12
- UBEWDCMIDFGDOO-UHFFFAOYSA-N cobalt(II,III) oxide Inorganic materials [O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3] UBEWDCMIDFGDOO-UHFFFAOYSA-N 0.000 abstract description 4
- 229910000831 Steel Inorganic materials 0.000 abstract description 3
- 239000010959 steel Substances 0.000 abstract description 3
- 238000007654 immersion Methods 0.000 description 23
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 21
- 238000012360 testing method Methods 0.000 description 18
- 150000001868 cobalt Chemical class 0.000 description 13
- 238000009472 formulation Methods 0.000 description 11
- 229910001512 metal fluoride Inorganic materials 0.000 description 9
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 9
- 239000007921 spray Substances 0.000 description 9
- 239000000376 reactant Substances 0.000 description 8
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000007789 sealing Methods 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 6
- 229910002651 NO3 Inorganic materials 0.000 description 6
- 125000000350 glycoloyl group Chemical group O=C([*])C([H])([H])O[H] 0.000 description 6
- 238000011160 research Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 5
- 235000011114 ammonium hydroxide Nutrition 0.000 description 5
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 5
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 4
- 239000005695 Ammonium acetate Substances 0.000 description 4
- 238000013019 agitation Methods 0.000 description 4
- 235000019257 ammonium acetate Nutrition 0.000 description 4
- 229940043376 ammonium acetate Drugs 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000003446 ligand Substances 0.000 description 4
- UEGPKNKPLBYCNK-UHFFFAOYSA-L magnesium acetate Chemical compound [Mg+2].CC([O-])=O.CC([O-])=O UEGPKNKPLBYCNK-UHFFFAOYSA-L 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 150000002826 nitrites Chemical class 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 239000004593 Epoxy Substances 0.000 description 3
- 150000001242 acetic acid derivatives Chemical class 0.000 description 3
- VSGNNIFQASZAOI-UHFFFAOYSA-L calcium acetate Chemical compound [Ca+2].CC([O-])=O.CC([O-])=O VSGNNIFQASZAOI-UHFFFAOYSA-L 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 150000004696 coordination complex Chemical class 0.000 description 3
- 150000004673 fluoride salts Chemical class 0.000 description 3
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 3
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 3
- 229910021580 Cobalt(II) chloride Inorganic materials 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 159000000021 acetate salts Chemical class 0.000 description 2
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 150000004700 cobalt complex Chemical class 0.000 description 2
- 230000000536 complexating effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000002823 nitrates Chemical class 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 235000013024 sodium fluoride Nutrition 0.000 description 2
- 239000011775 sodium fluoride Substances 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
- 229910000967 As alloy Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000531 Co alloy Inorganic materials 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910020261 KBF4 Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910017717 NH4X Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 150000003868 ammonium compounds Chemical class 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 238000002048 anodisation reaction Methods 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003788 bath preparation Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 150000001869 cobalt compounds Chemical class 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 229940044175 cobalt sulfate Drugs 0.000 description 1
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000013551 empirical research Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000007730 finishing process Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Inorganic materials [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 1
- 229940071125 manganese acetate Drugs 0.000 description 1
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 229940083542 sodium Drugs 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- JXKPEJDQGNYQSM-UHFFFAOYSA-M sodium propionate Chemical compound [Na+].CCC([O-])=O JXKPEJDQGNYQSM-UHFFFAOYSA-M 0.000 description 1
- 239000004324 sodium propionate Substances 0.000 description 1
- 235000010334 sodium propionate Nutrition 0.000 description 1
- 229960003212 sodium propionate Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000005211 surface analysis Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
- ZEBNDJQGEZXBCR-UHFFFAOYSA-H trisodium;cobalt(3+);hexanitrite Chemical compound [Na+].[Na+].[Na+].[Co+3].[O-]N=O.[O-]N=O.[O-]N=O.[O-]N=O.[O-]N=O.[O-]N=O ZEBNDJQGEZXBCR-UHFFFAOYSA-H 0.000 description 1
- LSGOVYNHVSXFFJ-UHFFFAOYSA-N vanadate(3-) Chemical class [O-][V]([O-])([O-])=O LSGOVYNHVSXFFJ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/56—Treatment of aluminium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
- C23C22/66—Treatment of aluminium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/68—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous solutions with pH between 6 and 8
Definitions
- This environmental-quality invention is in the field of chemical conversion coatings formed on metal substrates, for example, on aluminum substrates. More particularly, one aspect of the invention is a new type of oxide coating (which I refer to as a "cobalt conversion coating") which is chemically formed on metal substrates.
- the invention enhances the quality of the environment of mankind by contributing to the maintenance of air and water quality.
- chemical conversion coatings are formed chemically by causing the surface of the metal to be "converted" into a tightly adherent coating, all or part of which consists of an oxidized form of the substrate metal.
- Chemical conversion coatings can provide high corrosion resistance as well as strong bonding affinity for paint.
- the industrial application of paint (organic finishes) to metals generally requires the use of a chemical conversion coating, particularly when the performance demands are high.
- aluminum protects itself against corrosion by forming a natural oxide coating, the protection is not complete.
- aluminum alloys particularly of the high-copper 2000-series aluminum alloys, such as alloy 2024-T3, corrode much more rapidly than pure aluminum.
- the first is by anodic oxidation (anodization) in which the aluminum component is immersed in a chemical bath, such as a chromic or sulfuric acid bath, and an electric current is passed through the aluminum component and the chemical bath.
- a chemical bath such as a chromic or sulfuric acid bath
- an electric current is passed through the aluminum component and the chemical bath.
- the resulting conversion coating on the surface of the aluminum component offers resistance to corrosion and a bonding surface for organic finishes.
- the second type of process is by chemically producing a conversion coating, which is commonly referred to as a chemical conversion coating, by subjecting the aluminum component to a chemical solution, such as a chromic acid solution, but without using an electric current in the process.
- a chemical solution such as a chromic acid solution
- the chemical solution may be applied by immersion application, by manual application, or by spray application.
- the present invention relates to this second type of process for producing chemical conversion coatings.
- the chemical solution may be applied by immersion application, by various types of manual application, or by spray application.
- chromic acid process for forming chemical conversion coatings on aluminum substrates is described in various embodiments in Ostrader et al. U.S. Patent 2,796,370 and Ostrader et al. U.S. Patent 2,796,371, in military process specification MIL-C-5541, and in Boeing Process Specification BAC 5719.
- These chromic acid chemical conversion baths contain hexavalent chromium, fluorides, and cyanides, all of which present significant environmental as well as health and safety problems.
- chromic acid conversion bath such as ALODINE 1200
- Cr ⁇ 3 - "chromic acid” hexavalent chromium
- NaF - sodium fluoride KBF4 - potassium tetrafluoroborate
- Chromic acid conversion films as formed on aluminum substrates, meet a 168 hours corrosion resistance criterion, but they primarily serve as a surface substrate for paint adhesion. Because of their relative thinness and low coating weights (40-150 milligrams/ft ⁇ ), chromic acid conversion coatings do not cause a fatigue life reduction in the aluminum structure.
- the invention is a process for forming a cobalt conversion coating on a metal substrate, thereby imparting corrosion resistance and paint adhesion properties.
- the invention was developed as a replacement for the prior art chromic acid process. The process includes the steps of: (a) providing a cobalt
- the substrate may be aluminum, aluminum alloy, as well as Cd plated, Zn plated, Zn-Ni plated, and steel.
- the cobalt-III hexavalent complex is preferably present in the form of Me m [Co(R)6] n , wherein Me is Na, Li, K, Ca, Zn, Mg, or Mn, and wherein ⁇ i is 2 or
- n 1 or 2
- R is a carboxylate having 1 to 6 C atoms.
- the invention is a chemical conversion coating solution for producing a cobalt conversion coating on a metal substrate, the solution including an aqueous solution containing a soluble cobalt-III hexacarboxylate complex, the concentration of the cobalt-III hexacarboxylate complex being from about 0.01 mole per liter of solution to the saturation limit of the cobalt-III hexavalent complex.
- the cobalt conversion solution may be prepared by a bath makeup sequence including the steps of: (a) dissolving a soluble cobalt-II salt, preferably cobalt acetate, and (b) dissolving a metal acetate salt such as sodium, magnesium or calcium acetate to form a conversion coating solution.
- wetting agents such as alkyl fluorides, fluorocarbons, and metal fluorides can be added to the conversion coating solutions. Addition of these wetting agents eliminate the need for a costly sealing step following formation of the conversion coating.
- FIGURES 1 through 4 are photomicrographs (scanning electron microscope operated at 20 KV) of alloy 2024-T3 test panels with cobalt conversion coatings made by the invention.
- FIGURES 1 through 4 show a cobalt conversion coatings 410 formed by a 15 minute immersion in a typical cobalt conversion coating solution at 140°F.
- FIGURE 1 is a photomicrograph at XI 0,000 magnification of a test panel showing a cobalt conversation coating 410 of the invention.
- the photomicrograph is a top view of the upper surface of oxide coating 410.
- the top of oxide coating 410 is porous and looks like a sponge. This test panel was immersed in the cobalt conversion coating solution for 15 minutes.
- the white bar is a length of 1 micron.
- FIGURE 2 is a photomicrograph at X70,000 magnification of the test panel of FIGURE 1.
- the photomicrograph is a top view of the upper surface of oxide coating 410.
- FIGURE 2 is a close-up, at higher magnification, of a small area of the test panel.
- the white bar is a length of 1 micron.
- FIGURE 3 is a photomicron at XI 0,000 magnification of another test panel showing a side view, from an elevated angle, of a fractured cross section of a cobalt conversion coating 420 of the invention.
- the fractured cross section of the aluminum substrate of the test panel is indicated by reference numeral 422. This test panel was immersed in the coating bath for ⁇ 5 minutes. To make the photomicrograph, the test panel was bent and broken off to expose a cross section of oxide coating 420.
- the white bar is a length of 1 micron.
- FIGURE 4 is a photomicrograph at X70.000 magnification of the test panel of
- FIGURE 3 showing a side view, from an elevated angle, of a fractured cross section of cobalt conversion coating 420 of the invention.
- FIGURE 4 is a close-up, at higher magnification, of a small area of the test panel.
- the aluminum substrate of the test panel is indicated by reference numeral 422.
- the white bar is a length of 1 micron.
- FIGURE 5 is a graph showing the tradeoff between paint adhesion and corrosion resistance as a function of immersion time.
- the present invention relates to a new cobalt conversion coating.
- the cobalt conversion coating can be made so resistant to corrosion that the conventional sealing step is no longer required. This result is achieved by adding metal fluorides and wetting agents such as alkyl fluorides and fluorocarbons to the conversion coating solution. It is believed that the combination of the wetting agents and the metal fluorides ⁇ impart a small etch effect on the aluminum substrate surface which is believed to aid in the coating formation.
- Cobalt ammine complexes were thus produced with a number of reactants, i.e., Co(NO 3 6H 2 O, CoCl 2 « 6H 2 O, NH4NO3, NH4CI and NH4OH.
- the resultant coatings formed on aluminum substrates were found to have substantially improved corrosion resistant over the simple salt immersion described earlier.
- a review of cobalt complexing chemistry yielded the following information:
- the ammonium nitrate is used to prevent initial precipitation of the reaction products.
- This chemistry is extensively reviewed in prior copending application Serial No. 07/525,800, filed May 17, 1990.
- An examination of reaction (4) revealed however, that while well defined iridescent coatings could be formed on aluminum substrates, an excess of ammonia, i.e., NH4OH was required to drive this reaction.
- NH4OH ammonia
- the amount of excess ammonia in the bath had a pronounced effect on the paint adhesion and corrosion resistance characteristics of coatings formed by this method. Paint adhesion and corrosion performance ranged from superb to complete failure, depending on the amount of ammonia in the bath.
- Coatings formed by this method are strongly colored, similar to prior chromated coatings in appearance. Coating weights in excess of 350 mg/ft ⁇ can be achieved. Nitrates such as NaNO3, Mg(NO3) 2 » 6H 2 O or Ca(NO3) 2 * 6H O were added to this formulation to aid in coating firmness at higher coating weight thus avoiding powdery loose deposits. As a result of this research, two bath formulations that resulted in a clear coating and a colored coating were selected for further testing. The following two equations below establish the chemistries for the clear and colored cobalt conversion coatings. Clear Coat:
- Equation (12) NH 4 (C 2 H3O 2 ) in Equation (12) would eliminate the above competing reactions described in conjunction with complexes (13) and (14), and result in the same strong colored coatings as the original ammonium acetate solutions.
- Sodium acetate is the most preferred metal carboxylate.
- Other metal carboxylates such as zinc, lithium, potassium, and manganese acetate will work but are not preferred.
- the typical reactions are
- Metal fluorides such as MgF 2 and CaF 2 and wetting agents such as water soluble alkyl-fluorides and fluorocarbons can also be added in very small quantities to these solutions (Tables III and IV) to improve corrosion protection and manufacturing ease.
- alkyl fluoride wetting agents such as MSP-ST alkyl fluoride by M&T Harshaw, Cleveland, Ohio, and fluorocarbons FC99 or FC95 wetting agents by 3M Company, St. Paul, Minnesota, have been successfully used.
- the presence of the fluorinated wetting agents, metal fluorides, or mixtures thereof raise the corrosion performance level of resultant coatings to such a degree that sealing of these conversion coatings in a secondary seal step is no longer required.
- any water soluble fluorinated wetting agent capable of lowering liquid surface tension into the range of 30 to 40 dynes per centimeter at 20 °C is usable.
- Solutions operated as detailed below yield coatings that pass a 168 hours salt spray corrosion resistance criteria in accordance with Boeing Process Specification BAC 5719, "Chromated Conversion Coatings.”
- the single step conversion coating has yielded in excess of 240 hours of salt spray resistance before showing any sign of corrosion pitting. It became apparent during experimentation with formulations (16), (17) and
- Cobalt acetate is the most preferred soluble cobalt-II salt.
- Other water soluble cobalt salts such as Co NO3) 2 , C0SO 4 , CoCl 2 , C0PO 4 , C0CO3, may be substituted for cobalt acetate, but are not preferred for the reasons illustrated in Table I.
- These cobalt salts are preferably reacted with soluble metal carboxylates having from 1 to 5 carbon atoms, although metal salts of acetic acid are most preferred.
- the carboxylate salts of Ca, Mg, and Na are preferred, with the Na carboxylate being most preferred. while Zn, Li, K, and Mn may also be used.
- the limitations on using carboxylates other than the acetates is water solubility.
- carboxylates that will work are for example sodium propionate.
- the minimum solubility needed to produce an effective coating is about 0.01 moles of cobalt-II salt per liter of water at 20°C (68°F)
- the salts may be used up to their solubility limits.
- fluorinated wetting agents may be added to the bath as discussed above. When these wetting agents are employed, a conversion coating is created that does not need to be subjected to a conventional sealing step in order to exhibit satisfactory corrosion resistance.
- the concentration of dissolved cobalt-II salt used may be from about 0.01 mole per liter of final solution up to the solubility limit of the cobalt-II salt employed at 20 °C (68°F)
- the concentration of dissolved cobalt-II salt used may be from about 0 04 mole per liter of final solution up to 0.15 mole per liter of final solution
- the concentration of the cobalt-III hexcarboxylate coordination complex may be from about 0.01 mole per liter of final solution up to the solubility limit of the cobalt-III hexcarboxylate coordination complex employed.
- the concentration of the cobalt-III hexcarboxylate coordination complex may be from about 0.04 mole per liter of final solution up to 0.15 mole per liter of final solution.
- the concentration of dissolved metal carboxylate may be from about 0.03 to 2.5 moles per liter of final solution.
- concentration of dissolved metal carboxylate used may be from about 0.05 mole per liter of final solution up to 0.2 mole per liter of final solution.
- the concentration of the fluorinated wetting agents is preferably sufficient to hold solution surface tension between 30 " to 40 dynes per centimeter at 20°C.
- the metal fluorides, MgF and CaF 2 may be present in a concentration from 0 to solubility limit. It is to be understood that the fluorinated wetting agents, metal fluorides, or mixtures thereof are not required, but are preferred. If the wetting agents and metal fluorides are not used, the conversion coating must be subjected to a sealing step to achieve high corrosion resistance. By using the wetting agents and fluorides, the sealing step can be eliminated, thus making the use of the present invention even more economical.
- the pH of the bath may be from about 5.0 to 9.0 with 6.0 to 7.5 being
- the temperature of the bath may be from about 68°F to 160°F. Above 160°F, gradual decomposition of the cobalt-III hexcarboxylate complex may occur. The optimum temperature is 140 ⁇ 5 °F.
- the immersion time may be from about 3 minutes to 60 minutes, more preferably from 5 to 30 minutes. When sodium acetate is employed, the immersion time can be reduced to 5 to 8 minutes. Use of these parameters will result in coating weights ranging for example from 20 to 240 mg/ft 2 .
- a " stainless steel tank is equipped with air agitation and temperature control equipment capable of controlling temperature within ⁇ 5°F. (The tank may be lined with an inert material capable of withstanding
- the tank is filled to 3/4-full with deionized water and heated to 120°F Air agitation is commenced to achieve a gentle boil.
- the cobalt conversion coating should be applied after all trimming and fabrication have been completed. Parts, where solution entrapment is possible, should not be subjected to immersion alkaline cleaning or immersion deoxidizing; manual cleaning and manual deoxidizing procedures should be used to obtain water break- free surfaces before applying cobalt conversion treatment.
- a water break-free surface is a surface which maintains a continuous water film for a period of at least 30 seconds after having been sprayed or immersion rinsed in clean water at a temperature below 100°F.
- Vapor degrease may be performed in accordance with Boeing Process Specification BAC 5408. Emulsion clean in accordance with Boeing Process Specification BAC 5763, or solvent clean in accordance with Boeing Process Specification BAC 5750 if parts are greasy or oily. Parts with open faying surfaces or spot-welded joints where solution entrapment is possible should be immersed in cold water (or in hot and cold water) for 2 minutes after precleaning.
- Alkaline clean and rinse may be performed in accordance with Boeing Process Specification BAC 5749, except for parts with open faying surfaces or spot welded joints, in which case, rinsing should be for at least 10 minutes using agitation with multiple immersions (a minimum of four times) followed by manual spray rinsing as required to prevent solution entrapment.
- Deoxidize Deoxidize and rinse may be performed in accordance with Boeing Process
- Castings may be deoxidized by either of the following methods: a. Deoxidize in accordance with Boeing Process Specification BAC 5765, Solution 37, 38 or 39. b. Dry abrasive blast castings in accordance with Boeing Process Specification BAC 5748, Type II, Class 1 and rinse.
- Optimum bath temperature from the standpoint of corrosion and adhesion was found to be 140°F ⁇ 5°F.
- FIGURE 5 depicts the general behavior of cobalt conversion coatings with respect to corrosion performance vs. paint adhesion.
- the intercept point of the corrosion and adhesion curve represents the bath parameters where the two divergent properties (corrosion and adhesion) are at optimum with respect to each other.
- the pH be maintained between pH 6.0 and 7.5, although coatings have been produced between pH 5.0 and 9.0. Adjustments to the pH may be required after the solutions have been used for extended periods. Corrosion Resistance
- ESCA electron spectroscopy for chemical analysis (also known as XPS or X-ray photoelectron spectroscopy).) These analyses show that the cobalt conversion coating consists of a mixture of oxides, namely, aluminum oxide Al 2 O 3 as the largest volume percent, and cobalt oxides CoO, Co 3 O 4 , and Co 2 O 3 .
- the term “largest volume percent” means that the volume of this oxide exceeds the volume of any other oxide which is present, but the term “largest volume percent” means that the volume of this oxide exceeds the volume of any other oxide which is present, but the term “largest volume present” does not necessarily imply that the volume of this oxide is more than 50 volume percent.
- the data further shows that in the lower portion of the oxide coating (that is, next to the aluminum substrate), the largest volume percent is Al 2 O 3 .
- the middle portion of the oxide coating is a mixture of CoO, Co 2 O 3 , Co 3 O4, and Al O 3 .
- the data shows that in the top portion of the oxide coating, the largest volume percent is a mixture of Co 2 O 3 and Co 3 O 4 .
- FIGS. 1 through 4 show a cobalt conversion coating 410 and 420 formed by a 15 minute immersion in a typical cobalt conversion coating solution.
- the top surface of the cobalt conversion coating as shown in FIGS. 1 through 4 bears a resemblance to a sponge, thus providing substantial surface area and porosity for good paint adhesion. Below the top surface, the coating becomes more dense and solid (non- porous).
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Abstract
(A) A process for forming a cobalt conversion coating on a metal substrate, thereby imparting corrosion resistance and paint adhesion properties. The invention was developed as a replacement for the prior art chromic acid process. The process includes the steps of: (a) providing a cobalt conversion solution comprising an aqueous solution containing a soluble cobalt-III hexavalent complex, the concentration of the cobalt-III hexavalent complex being from about 0.01 mole per liter of solution to the solubility limit of the cobalt-III hexavalent complex; and (b) contacting the substrate with the solution for a sufficient amount of time, whereby the cobalt conversion coating is formed. The substrate may be aluminum or aluminum alloy, as well as Cd plated, Zn plated, Zn-Ni plated, and steel. The cobalt-III hexavalent complex may be present in the form of Mem[Co(R)6]n, wherein Me is Na, Li, K, Ca, Zn, Mg, or Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms. (B) A chemical conversion coating solution for producing the cobalt conversion coating on a metal substrate, the solution including an aqueous solution containing a soluble cobalt-III hexavalent complex, the concentration of the cobalt-III hexavalent complex being from about 0.01 mole per liter of solution to the solubility limit of the cobalt-III hexavalent complex. (C) A coated article exhibiting acceptable corrosion resistance and paint adhesion properties, the article including: (a) a metal substrate; and (b) a cobalt conversion coating formed on the substrate, the cobalt conversion coating including aluminum oxide Al2O3 as the largest volume percent, and cobalt oxides CoO, Co2O3, and Co3O4.
Description
NON-CHROMATED OXIDE COATING FOR ALUMINUM SUBSTRATES
Field of the Invention This environmental-quality invention is in the field of chemical conversion coatings formed on metal substrates, for example, on aluminum substrates. More particularly, one aspect of the invention is a new type of oxide coating (which I refer to as a "cobalt conversion coating") which is chemically formed on metal substrates. The invention enhances the quality of the environment of mankind by contributing to the maintenance of air and water quality.
Background of the Invention
In general, chemical conversion coatings are formed chemically by causing the surface of the metal to be "converted" into a tightly adherent coating, all or part of which consists of an oxidized form of the substrate metal. Chemical conversion coatings can provide high corrosion resistance as well as strong bonding affinity for paint. The industrial application of paint (organic finishes) to metals generally
requires the use of a chemical conversion coating, particularly when the performance demands are high.
Although aluminum protects itself against corrosion by forming a natural oxide coating, the protection is not complete. In the presence of moisture and electrolytes, aluminum alloys, particularly of the high-copper 2000-series aluminum alloys, such as alloy 2024-T3, corrode much more rapidly than pure aluminum.
In general, there are two types of processes for treating aluminum to form a beneficial conversion coating. The first is by anodic oxidation (anodization) in which the aluminum component is immersed in a chemical bath, such as a chromic or sulfuric acid bath, and an electric current is passed through the aluminum component and the chemical bath. The resulting conversion coating on the surface of the aluminum component offers resistance to corrosion and a bonding surface for organic finishes.
The second type of process is by chemically producing a conversion coating, which is commonly referred to as a chemical conversion coating, by subjecting the aluminum component to a chemical solution, such as a chromic acid solution, but without using an electric current in the process. The chemical solution may be applied by immersion application, by manual application, or by spray application. The
^resulting conversion coating on the surface of the aluminum component offers resistance to corrosion and a bonding surface for organic finishes. The present invention relates to this second type of process for producing chemical conversion coatings. The chemical solution may be applied by immersion application, by various types of manual application, or by spray application.
One widely-used chromic acid process for forming chemical conversion coatings on aluminum substrates is described in various embodiments in Ostrader et al. U.S. Patent 2,796,370 and Ostrader et al. U.S. Patent 2,796,371, in military process specification MIL-C-5541, and in Boeing Process Specification BAC 5719. These chromic acid chemical conversion baths contain hexavalent chromium, fluorides, and cyanides, all of which present significant environmental as well as health and safety problems. The constituents of a typical chromic acid conversion bath, such as ALODINE 1200, are as follows: Crθ3 - "chromic acid" (hexavalent chromium); NaF - sodium fluoride; KBF4 - potassium tetrafluoroborate;
K^ZrFg - potassium hexafluorozirconate; K3 Fe(CN)6 potassium ferricyanide; and,
HNO3 - nitric acid (for pH control).
Many aluminum structural parts, as well as Cd plated, Zn plated, Zn-Ni plated, and steel pans, throughout the aircraft and aerospace industry are currently being
treated using this chromic acid process technology. Chromic acid conversion films, as formed on aluminum substrates, meet a 168 hours corrosion resistance criterion, but they primarily serve as a surface substrate for paint adhesion. Because of their relative thinness and low coating weights (40-150 milligrams/ft^), chromic acid conversion coatings do not cause a fatigue life reduction in the aluminum structure.
However, environmental regulations in the United States, particularly in California, and in other countries are drastically reducing the allowed levels of hexavalent chromium compounds in effluents and emissions from metal finishing processes. Accordingly, chemical conversion processes employing hexavalent chromium compounds must be replaced. The present invention, which does not employ hexavalent chromium compounds, is intended to replace the previously used chromic acid process for forming conversion coatings on aluminum substrates.
Summary of the Invention
A. In one respect, the invention is a process for forming a cobalt conversion coating on a metal substrate, thereby imparting corrosion resistance and paint adhesion properties. The invention was developed as a replacement for the prior art chromic acid process. The process includes the steps of: (a) providing a cobalt
~ conversion solution comprising an aqueous solution containing a soluble cobalt-III hexavalent complex, the concentration to the cobalt-III hexavalent complex being from about 0.01 mole per liter of solution to the saturation limit of the cobalt-III hexavalent complex; and (b) contacting the substrate with the solution for a sufficient amount of time, whereby the cobalt conversion coating is formed. The substrate may be aluminum, aluminum alloy, as well as Cd plated, Zn plated, Zn-Ni plated, and steel.
The cobalt-III hexavalent complex is preferably present in the form of Mem[Co(R)6]n, wherein Me is Na, Li, K, Ca, Zn, Mg, or Mn, and wherein πi is 2 or
3, n is 1 or 2, and R is a carboxylate having 1 to 6 C atoms.
B. In another aspect, the invention is a chemical conversion coating solution for producing a cobalt conversion coating on a metal substrate, the solution including an aqueous solution containing a soluble cobalt-III hexacarboxylate complex, the concentration of the cobalt-III hexacarboxylate complex being from about 0.01 mole per liter of solution to the saturation limit of the cobalt-III hexavalent complex. The cobalt conversion solution may be prepared by a bath makeup sequence including the steps of: (a) dissolving a soluble cobalt-II salt, preferably cobalt acetate, and (b) dissolving a metal acetate salt such as sodium, magnesium or calcium acetate to form a conversion coating solution.
C. In yet another aspect to the invention, wetting agents such as alkyl fluorides, fluorocarbons, and metal fluorides can be added to the conversion coating solutions. Addition of these wetting agents eliminate the need for a costly sealing step following formation of the conversion coating. Brief Description of the Drawings
The figures herein contained are photomicrographs of images produced by a scanning electron microscope of coatings on aluminum alloy test panels. FIGURES 1 through 4 are photomicrographs (scanning electron microscope operated at 20 KV) of alloy 2024-T3 test panels with cobalt conversion coatings made by the invention. FIGURES 1 through 4 show a cobalt conversion coatings 410 formed by a 15 minute immersion in a typical cobalt conversion coating solution at 140°F.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIGURE 1 is a photomicrograph at XI 0,000 magnification of a test panel showing a cobalt conversation coating 410 of the invention. The photomicrograph is a top view of the upper surface of oxide coating 410. The top of oxide coating 410 is porous and looks like a sponge. This test panel was immersed in the cobalt conversion coating solution for 15 minutes. The white bar is a length of 1 micron.
FIGURE 2 is a photomicrograph at X70,000 magnification of the test panel of FIGURE 1. The photomicrograph is a top view of the upper surface of oxide coating 410. FIGURE 2 is a close-up, at higher magnification, of a small area of the test panel. The white bar is a length of 1 micron. FIGURE 3 is a photomicron at XI 0,000 magnification of another test panel showing a side view, from an elevated angle, of a fractured cross section of a cobalt conversion coating 420 of the invention. The fractured cross section of the aluminum substrate of the test panel is indicated by reference numeral 422. This test panel was immersed in the coating bath for \ 5 minutes. To make the photomicrograph, the test panel was bent and broken off to expose a cross section of oxide coating 420. The white bar is a length of 1 micron.
FIGURE 4 is a photomicrograph at X70.000 magnification of the test panel of
FIGURE 3 showing a side view, from an elevated angle, of a fractured cross section of cobalt conversion coating 420 of the invention. FIGURE 4 is a close-up, at higher magnification, of a small area of the test panel. The aluminum substrate of the test panel is indicated by reference numeral 422. The white bar is a length of 1 micron.
FIGURE 5 is a graph showing the tradeoff between paint adhesion and corrosion resistance as a function of immersion time.
Detailed Description of the Preferred Embodiment
The present invention relates to a new cobalt conversion coating. The cobalt conversion coating can be made so resistant to corrosion that the conventional sealing step is no longer required. This result is achieved by adding metal fluorides and wetting agents such as alkyl fluorides and fluorocarbons to the conversion coating solution. It is believed that the combination of the wetting agents and the metal fluorides^ impart a small etch effect on the aluminum substrate surface which is believed to aid in the coating formation.
By way of background leading up to this invention, the subject matter set forth in my prior copending applications will be reviewed. A considerable amount of empirical research was conducted in order to arrive at the present invention A variety of multivalent compounds was investigated, used either by themselves or in combination with alkalis, acids, or fluorides. Among these compounds were vanadates, molybdates, cerates, ferrates and variety of borates. While film deposition of compounds, containing these elements on aluminum alloy substrates has been achieved, none afforded any appreciable corrosion protection nor paint adhesion.
Cobalt ammine complexes were thus produced with a number of reactants, i.e., Co(NO3 6H2O, CoCl2« 6H2O, NH4NO3, NH4CI and NH4OH. The resultant coatings formed on aluminum substrates were found to have substantially improved corrosion resistant over the simple salt immersion described earlier. A review of cobalt complexing chemistry yielded the following information:
When a stream of air is drawn for several hours through a solution of cobalt-II salt, containing ammonium hydroxide, the corresponding ammonium salt and activated charcoal, then hexammine salts are obtained:
4 Co X2 + 4 NH4X + 20 NH3 + O2 > 4[Co(NH3)6] X3 + water, ( 1 )
wherein X = Cl, Br, NO3, CN, SCN, PO4, SO4, C2H3O2, and CO3. In the absence of activated charcoal, replacement will occur to give:
[Co(NH3)5 X]2+ (2)
These generic reactions are based on the fact that cobalt-II salts have a very strong tendency to oxidize to cobalt-III complexes, i.e.,
[Co(NH3)6 X]2+ — [Co(NH3)6 X]3+ + e- (3)
These reactions are not new and have been studied extensively. Cobalt-III complexes are typically made in the photo development industry as oxidizers to enhance clarity of color photography. What is surprising, however, is that cobalt complexes are capable of forming oxide structures on aluminum substrates. The exact reaction mechanism of this oxide formation is not completely understood, but is believed to function on the chemical equilibrium in Equation (3).
This oxidizing tendency is considered to be responsible for the formation of oxide films on aluminum substrates. Bath formulations were made up successfully using the following chemical balances below:
4 Co(NO3) *6H2O + 4 NH4NO3 + 20 NH4OH + oxygen >
4 [Co(NH3)6] (NO3)3 + H2O (4)
The ammonium nitrate is used to prevent initial precipitation of the reaction products. This chemistry is extensively reviewed in prior copending application Serial No. 07/525,800, filed May 17, 1990. An examination of reaction (4) revealed however, that while well defined iridescent coatings could be formed on aluminum substrates, an excess of ammonia, i.e., NH4OH was required to drive this reaction. As a consequence, it is difficult to control the pH of the bath due to the high evaporation rates of ammonia from the solution. Furthermore, the amount of excess ammonia in the bath had a pronounced effect on the paint adhesion and corrosion resistance characteristics of coatings formed by this method. Paint adhesion and corrosion performance ranged from superb to complete failure, depending on the amount of ammonia in the bath.
A major advancement of this technology was achieved when a change in the portion of the complex that includes the ligand (the bracketed portion of formula (6)) within the cobalt complex was attempted. The development of the ammoniated cobalt complexes as described under reactions (1) through (4) established the bath chemistries as 3 valent cobalt amine complexes, i.e.,
[Co(NH3)6]X3 (5) wherein X = CI, Br, NO3, CN, SCN, PO , SO4, C2H3O2> CO3, and wherein the " portion of the complex that includes the ligand is positively charged, i.e.,
[Co(NH3)6]3+ (6)
With the substitution of nitrite compounds for the ammonium compounds the formation of 3 -valent cobalt complexes such as
Me3[Co(NO )6], wherein Me = Na, Li, K (7) was achieved where the portion of the complex that includes the ligand is negatively charged, i.e.,
[Co(NO2)6]3- (8) This nitrite complexed chemistry was found to be completely self controlling with a stable pH in the region 6.8 to 7.2. Paint adhesion performance was also found to be substantially superior to prior chromated films. This chemistry is extensively discussed in my prior copending application Serial No. 07/621, 132. Two pronounced characteristics of conversion films formed with this nitrite technology was the almost clear (very light iridescence) surface appearance and the coating film weights which were limited at 90 rήg/ft2 maximum. These two limitations led to further research work to investigate the feasibility of obtaining coatings with strong, easily inspectable color indication along with higher coating weights, i.e., in excess of 90 mg/ft^.
Successful formulations were finally made with the introduction of acetates to form complexes such as
Me3[Co(C2H3O2)6] (9) where the portion of the complex that includes the ligand is also negatively charged, i.e.,
[Co(C2H3O2)6]3- (10) Coatings formed by this method are strongly colored, similar to prior chromated coatings in appearance. Coating weights in excess of 350 mg/ft^ can be achieved. Nitrates such as NaNO3, Mg(NO3)2 » 6H2O or Ca(NO3)2* 6H O were added to this formulation to aid in coating firmness at higher coating weight thus avoiding powdery loose deposits. As a result of this research, two bath formulations that resulted in a clear coating and a colored coating were selected for further testing. The following two equations below establish the chemistries for the clear and colored cobalt conversion coatings. Clear Coat:
Co(NO3)2 • 6H2O + 6NaNO + l/2H2O2 →
Na3[Co(NO2)6] + 2NaNO3 + 2NaOH (11)
Colored Coat:
Co(NO3)2 • 6H2O + 6CH3COONH4 l/2H2O2 →
Na3[Co(C2H3O2)6] + 2NH4NO3 + NH4OH (12)
When coatings are produced by equations (11) and (12) and are sealed subsequently in special formulated solutions, up to 140 hours of salt spray corrosion resistance are obtained when tested in accordance with ASTM Bl 17. This chemistry is extensively discussed in my prior copending application Serial No. 07/732,568.
The research advances described up to this point involve conversion coatings formed from the reaction of a 2-valent cobalt salt such as Co(NO3)2 « 6H2O with ammonium acetate (CH3COONH4) to form a 3 -valent cobalt complex. The resultant coatings are of superb quality with regard to defined performance criteria; however, the bath life of solutions utilizing ammonium acetate are rather short, i.e., on the order of 30 to 40 days. The desire to extend this bath life was the basis for further research that was just recently completed. This work has now progressed to overall process and coating performance improvements in accordance with the present invention, as discussed in further detail below.
During testing of the ammonium acetate complexed cobalt solution (Equation (12)), it was noticed that after several weeks of normal tank operation the coating weights on aluminum substrates would gradually drop off and the" color intensity would become lighter. In order to compensate for this, ever increasing immersion times were required. It was also noticed that a gradual solution appearance change would occur over time, from a dark brown to wine red color. Analysis finally established that a competing reaction was taking place over time, where the acetate in the complex
[Co(C2H3O2)6]3- ( 13) would gradually be replaced by an ammonia to form the complex
[Co(NH3)6]3+ (14)
Notice the valence change in these bracketed ionic species.
In an effort to solve this problem it was discovered, in accordance with the present invention, that the substitution of a metal acetate such as
Na(C2H3O2) • 3H2O, Mg(C2H3O2)2 • 4H2O, or Ca(C2H3O2)2 • H2O for the
NH4(C2H3O2) in Equation (12) would eliminate the above competing reactions described in conjunction with complexes (13) and (14), and result in the same strong
colored coatings as the original ammonium acetate solutions. Sodium acetate is the most preferred metal carboxylate. Other metal carboxylates such as zinc, lithium, potassium, and manganese acetate will work but are not preferred. The typical reactions are
2Co(C2H3O2)2 • 4H2O + 3 Mg(C H3O2)2 • 4H2O
+2HC2H3O2 ► Mg3[Co(C2H3O2)6]2 + 21H2O (15)
Co(C2H3O2)2 • 4H2O + 3Ca(C2H3O2)2 • H2O +1/2 O2 + 2HC2H3O2 > Ca3[Co(C2H3O2)6]2 + 21H2O (16)
Co(C2H3O2)2 • 4H2O + 3Na(C2H3O2) • 3H2O + l/4O2 + HC2H3O2 >Na3[Co(C2H3O2)6] + 13 l/2H2O (17)
These reactions are carried out by bubbling air through the solution without the use of hydrogen peroxide. The acetic acid is not added as a reactant, but is formed in solution as part of the complex chemical reaction. The resultant conversion coatings are further improved in corrosion resistance over those conversion coating solutions produced by the reactions of Equations (11) and (12) when subjected to salt spray testing per ASTM Bl 17. In the broader context, it has been found that a cobalt conversion coating having superior performance characteristics can be produced by reacting a soluble cobalt salt with a metal carboxylate in accordance with the following general formula
Soluble Cobalt Salt + Me(R)x ►Mem[Co(R)6]n, (18) wherein x can be 1 or 2, m is 3, n is 1 or 2, Me is selected from the group consisting of Na, Li, K, Ca, Zn, Mg, and Mn, and wherein R is a carboxylate having from 1 to 5 carbon (C) atoms, provided the carboxylates are soluble in the reaction solution.
Metal fluorides such as MgF2 and CaF2 and wetting agents such as water soluble alkyl-fluorides and fluorocarbons can also be added in very small quantities to these solutions (Tables III and IV) to improve corrosion protection and manufacturing ease. In particular alkyl fluoride wetting agents such as MSP-ST alkyl fluoride by M&T Harshaw, Cleveland, Ohio, and fluorocarbons FC99 or FC95 wetting agents by 3M Company, St. Paul, Minnesota, have been successfully used. The presence of the fluorinated wetting agents, metal fluorides, or mixtures thereof
raise the corrosion performance level of resultant coatings to such a degree that sealing of these conversion coatings in a secondary seal step is no longer required. In principle any water soluble fluorinated wetting agent capable of lowering liquid surface tension into the range of 30 to 40 dynes per centimeter at 20 °C is usable. Solutions operated as detailed below yield coatings that pass a 168 hours salt spray corrosion resistance criteria in accordance with Boeing Process Specification BAC 5719, "Chromated Conversion Coatings." The single step conversion coating has yielded in excess of 240 hours of salt spray resistance before showing any sign of corrosion pitting. It became apparent during experimentation with formulations (16), (17) and
(18) that certain parameters are critical with respect to both make-up, chemistry and consistency of coating performance. These parameters were found to be bath makeup and process sequence, reactant selection and bath concentrations, temperature control, and immersion times. It must also be emphasized that the reaction system created is very complex and involves several simultaneous reversible reactions. It is believed that the entire reaction system must be present at or near an equilibrium condition in order to achieve optimum results in accordance with the present invention.
Reactant Selection and Solution Concentrations The most critical parameters affecting performance of conversion coatings with respect to paint adhesion and corrosion resistance were found to be selection of the reactants and their concentrations in solution. It was found that coating performance was affected foremost by these factors rather than bath temperature or immersion time, although temperature and immersion time do impart their effects over larger variations of these parameters.
It is known that with respect to surface treatments of aluminum, paint adhesion and corrosion resistance are divergent properties. In other words, maximizing paint adhesion usually occurs at the expense of corrosion performance and vice-versa. This surface treatment behavior was also found to exist with cobalt conversion coatings. The research carried out and described in this and the aforementioned prior copending applications has established a preferential list with regard to the various cobalt compounds and their corrosion resistance effectiveness versus paint adhesion.
TABLE I - Performance Rating of Cobalt Salts Using Metal Acetates for Complexing Component Corrosion Resistance Paint Adhesion
Cobalt Acetate + Me Acetate 1 2 Cobalt Nitrate f Me Acetate 3 1
Cobalt Sulfate + Me Acetate 2 4
Cobalt Chloride -t- Me Acetate 4 3
Rating: 1 = best, 4 = worst
It can be seen from Table I that the cobalt acetate formulations present the best possible combination with respect to corrosion resistance while maintaining good paint adhesion performance. It should be noted, however, that in cases where corrosion performance is not a factor, nitrates or nitrites yield the best paint adhesion performance that is achievable with these cobalt complexed salts
Cobalt acetate is the most preferred soluble cobalt-II salt. Other water soluble cobalt salts such as Co NO3)2, C0SO4, CoCl2, C0PO4, C0CO3, may be substituted for cobalt acetate, but are not preferred for the reasons illustrated in Table I. These cobalt salts are preferably reacted with soluble metal carboxylates having from 1 to 5 carbon atoms, although metal salts of acetic acid are most preferred. The carboxylate salts of Ca, Mg, and Na are preferred, with the Na carboxylate being most preferred. while Zn, Li, K, and Mn may also be used. The limitations on using carboxylates other than the acetates is water solubility. Other carboxylates that will work are for example sodium propionate. The minimum solubility needed to produce an effective coating is about 0.01 moles of cobalt-II salt per liter of water at 20°C (68°F) The salts may be used up to their solubility limits. Although not required, fluorinated wetting agents may be added to the bath as discussed above. When these wetting agents are employed, a conversion coating is created that does not need to be subjected to a conventional sealing step in order to exhibit satisfactory corrosion resistance.
Chemical Concentration. pH Control. Temperature, and Immersion Time With respect to chemical concentrations, the concentration of dissolved cobalt-II salt used may be from about 0.01 mole per liter of final solution up to the solubility limit of the cobalt-II salt employed at 20 °C (68°F) Preferably, the concentration of dissolved cobalt-II salt used may be from about 0 04 mole per liter of final solution up to 0.15 mole per liter of final solution The concentration of the cobalt-III hexcarboxylate coordination complex may be from about 0.01 mole per liter of final solution up to the solubility limit of the
cobalt-III hexcarboxylate coordination complex employed. Preferably, the concentration of the cobalt-III hexcarboxylate coordination complex may be from about 0.04 mole per liter of final solution up to 0.15 mole per liter of final solution.
The concentration of dissolved metal carboxylate, preferably a metal acetate, may be from about 0.03 to 2.5 moles per liter of final solution. Preferably, the concentration of dissolved metal carboxylate used may be from about 0.05 mole per liter of final solution up to 0.2 mole per liter of final solution.
When employed, the concentration of the fluorinated wetting agents is preferably sufficient to hold solution surface tension between 30 "to 40 dynes per centimeter at 20°C. The metal fluorides, MgF and CaF2, may be present in a concentration from 0 to solubility limit. It is to be understood that the fluorinated wetting agents, metal fluorides, or mixtures thereof are not required, but are preferred. If the wetting agents and metal fluorides are not used, the conversion coating must be subjected to a sealing step to achieve high corrosion resistance. By using the wetting agents and fluorides, the sealing step can be eliminated, thus making the use of the present invention even more economical.
The pH of the bath may be from about 5.0 to 9.0 with 6.0 to 7.5 being
~preferred and 6.5 being most preferred. The temperature of the bath may be from about 68°F to 160°F. Above 160°F, gradual decomposition of the cobalt-III hexcarboxylate complex may occur. The optimum temperature is 140 ± 5 °F. The immersion time may be from about 3 minutes to 60 minutes, more preferably from 5 to 30 minutes. When sodium acetate is employed, the immersion time can be reduced to 5 to 8 minutes. Use of these parameters will result in coating weights ranging for example from 20 to 240 mg/ft2. Preferred Bath Preparation Sequence
The following bath make up sequence is preferred for the acetate complexed cobalt solution:
1. A" stainless steel tank is equipped with air agitation and temperature control equipment capable of controlling temperature within ±5°F. (The tank may be lined with an inert material capable of withstanding
150°F continuous operation.)
2. The tank is filled to 3/4-full with deionized water and heated to 120°F Air agitation is commenced to achieve a gentle boil.
3. The applicable amount of metal acetate salt is now added and dissolved. For larger tanks a fine meshed holding basked will serve as a holding device aiding in the dissolution of the material.
4. The applicable amount of cobalt salt is then added and dissolved. A gentle air boil of the tank solution is maintained for another four hours at which time the reaction is mostly completed. A holding basket may also be used to aid in dissolution.
5. The solution is now heated to 140°F and the required small amounts of fluorinated wetting agent are added. Air agitation is maintained for an additional two hours. The tank is now ready for operation. Preferred Overall Processing Sequence
The preferred overall processing sequence may be summarized as follows: 1. Preclean
2. Mask and Rack
3. Alkaline Clean
4. Rinse at Room Temperature
5. Deoxidize 6. Rinse at Room Temperature
7. Form Oxide Conversion Coating
8. Rinse at Room Temperature
9. Dry
General Notes With Respect To The Above Process Flow Charts The cobalt conversion coating should be applied after all trimming and fabrication have been completed. Parts, where solution entrapment is possible, should not be subjected to immersion alkaline cleaning or immersion deoxidizing; manual cleaning and manual deoxidizing procedures should be used to obtain water break- free surfaces before applying cobalt conversion treatment. A water break-free surface is a surface which maintains a continuous water film for a period of at least 30 seconds after having been sprayed or immersion rinsed in clean water at a temperature below 100°F.
Thorough rinsing and draining throughout processing is necessary as each solution should be completely removed to avoid interference with the performance of the next solution in the sequence. Parts should be processed from one step to the next without delay and without allowing the parts to dry. When it is necessary to handle wet parts, clean latex rubber gloves should be worn. After conversion coating, handle dry parts only with clean fabric gloves. For processing systems which require part clamping, the number and size of contact points should be kept to a minimum as necessary for adequate mechanical support.
Preclean
Vapor degrease may be performed in accordance with Boeing Process Specification BAC 5408. Emulsion clean in accordance with Boeing Process Specification BAC 5763, or solvent clean in accordance with Boeing Process Specification BAC 5750 if parts are greasy or oily. Parts with open faying surfaces or spot-welded joints where solution entrapment is possible should be immersed in cold water (or in hot and cold water) for 2 minutes after precleaning. Mask and Rack
Areas which do not require cobalt conversion coatings should be masked with maskants. Dissimilar metal inserts (except chromium, nickel or cobalt alloy or plating, CRES, or titanium) and non-aluminum coated plasma flame sprayed area should be masked off. Parts are then racked in holding baskets or mounted on holding fixtures. Alkaline Clean
Alkaline clean and rinse may be performed in accordance with Boeing Process Specification BAC 5749, except for parts with open faying surfaces or spot welded joints, in which case, rinsing should be for at least 10 minutes using agitation with multiple immersions (a minimum of four times) followed by manual spray rinsing as required to prevent solution entrapment. Deoxidize Deoxidize and rinse may be performed in accordance with Boeing Process
Specification BAC 5765 except for parts where solution entrapment is possible, which parts may be rinsed using the method described above under "Alkaline Cleaning". Castings may be deoxidized by either of the following methods: a. Deoxidize in accordance with Boeing Process Specification BAC 5765, Solution 37, 38 or 39. b. Dry abrasive blast castings in accordance with Boeing Process Specification BAC 5748, Type II, Class 1 and rinse.
A specific solution formulation within the scope of the invention is as set forth in TABLE II, below.
TABLE II Preferred Solution Formulation
Components- Makeup Per Liter Control Range
Cobalt Acetate 33.0 gm 30 - 35 gm Co(C2H3O2)2*4H20
Magnesium Acetate 85.0 gm 80 - 90 gm Mg(C2H3O2)2-4H20
or
Calcium Acetate 70.0 gm 65 - 75 gm Ca(C2H3O2)2-H20
or
Operating Temperature
Immersion Time
'Coatings formed with this technology do not require sealing for corrosion resistance. ^Maintain solution surface tension between 30 to 40 dynes per centimeter.
Bath temperature variations and immersion times also contribute to corrosion performance and paint adhesion, however, to a significantly lesser degree than the solution reactant selection. It was determined that the variations in both temperatures and immersion time will affect the coating thickness primarily while the reactant materials primarily influence coating structure and density. The following general performance effects were observed:
1. Optimum bath temperature from the standpoint of corrosion and adhesion was found to be 140°F ± 5°F.
2. An increase in bath temperature from optimum does result in thicker and looser coatings and thus a decrease in paint adhesion with an increase in corrosion resistance.
3. A decrease in bath temperature from optimum results in thinner coatings with an increase in paint adhesion and a decrease in corrosion resistance. 4. The optimum time was found to be a function of reactant selection.
5. For nitrite complexed cobalt salts the optimum immersion time was 20-25 minutes at optimum bath temp.
6. For acetate complexed cobalt salts the optimum immersion was found to be a function of the type of acetate being used, i.e.
For Na(C2H3O2) 5 - 8 min @ 140°F
For Mg(C2H3O2)2 15 . 0 min @ 140°F
For Ca(C2H3O2)2 12 - 15 min @ 140°F FIGURE 5 depicts the general behavior of cobalt conversion coatings with respect to corrosion performance vs. paint adhesion. The intercept point of the corrosion and adhesion curve represents the bath parameters where the two divergent properties (corrosion and adhesion) are at optimum with respect to each other.
It is preferred that the pH be maintained between pH 6.0 and 7.5, although coatings have been produced between pH 5.0 and 9.0. Adjustments to the pH may be required after the solutions have been used for extended periods. Corrosion Resistance
Utilizing the basic corrosion resistance behavior of complexed cobalt salts, as shown above, the cobalt acetate formulations were investigated extensively. Cobalt acetate was complexed with sodium acetate Na(C2H3θ ) • 3 H2O or magnesium acetate Mg(C2H3θ2)2 • 4H2O. The results show that these formulations have excellent corrosion resistance without a subsequent seal step. Salt spray corrosion testing was conducted in accordance with ASTM Bl 17 and all specimens were
subjected to 168 hr. exposure. See Tables III and IV for results. The test conditions were repeated two more times and near identical results to Tables III and IV were obtained. Analysis of this data in conjunction with basic paint adhesion data, as well as other solution maintenance parameters has resulted in the optimum tank makeup and controls as listed under Table II, above. A final question on corrosion performance and color iridescence was answered with this work. This research established why sodium acetate Na(C2H3θ2) • 3H2O was chosen as the most preferred complexer over magnesium acetate Mg(C2H_3θ2)2 • 4H O. The reason is that sodium acetate imparts a somewhat more aggressive etch effect" on the aluminum substrate. This by itself was found to be very detrimental to corrosion performance. However, when sodium acetate was chemically formulated with wetting agents and metal fluorides, it had the distinct advantage that bright color iridescence of coatings were maintained while corrosion resistance was not impaired. On the other hand, when magnesium acetate or calcium acetate were utilized in conjunction with the wetting agents and metal fluorides very little etch effect was imparted and resultant coatings were rather weak in color effect.
Table HI
TYPE I - Chromated epoxy primer (aircraft high-performance coating)
TYPE II - Non-chromated epoxy enamel topcoat (aircraft high performance coating)
- Boeing Material Specification BMS 10-11 is a highly cross-linked epoxy primer system and details the performance requirements of these coaungs.
Qxide Coating Analyses
ESCA surface analysis, using a Perkin-Elmer Model 550 surface analyzer, and Auger oxide profiles, using the same machine (in a different operating mode), have been performed in order to characterize the cobalt conversion coatings of the invention. (ESCA = electron spectroscopy for chemical analysis (also known as XPS or X-ray photoelectron spectroscopy).) These analyses show that the cobalt conversion coating consists of a mixture of oxides, namely, aluminum oxide Al2O3 as the largest volume percent, and cobalt oxides CoO, Co3O4, and Co2O3. The term "largest volume percent" means that the volume of this oxide exceeds the volume of any other oxide which is present, but the term "largest volume percent" means that the volume of this oxide exceeds the volume of any other oxide which is present, but the term "largest volume present" does not necessarily imply that the volume of this oxide is more than 50 volume percent. The data further shows that in the lower portion of the oxide coating (that is, next to the aluminum substrate), the largest volume percent is Al2O3. The middle portion of the oxide coating is a mixture of CoO, Co2O3, Co3O4, and Al O3. And the data shows that in the top portion of the oxide coating, the largest volume percent is a mixture of Co2O3 and Co3O4. Additional characterization of the cobalt conversion coatings of the invention may be found in FIGS. 1 through 4 and in t ie descriptions of FIGS. 1 through 4 above. FIGS. 1 through 4 show a cobalt conversion coating 410 and 420 formed by a 15 minute immersion in a typical cobalt conversion coating solution. The top surface of the cobalt conversion coating, as shown in FIGS. 1 through 4 bears a resemblance to a sponge, thus providing substantial surface area and porosity for good paint adhesion. Below the top surface, the coating becomes more dense and solid (non- porous). Other Methods of Application
The above formulation illustrates producing cobalt conversion coatings by immersion application. The same principles apply to producing the conversion coating by manual application and by spray application.
As will be apparent to those skilled in the art to which the invention is addressed, the present invention may be embodied in forms other than those specifically disclosed above, without departing from the spirit or essential characteristics of the invention. The particular embodiments of the invention described above and the particular details of the processes described are therefore to
be considered in all respects as illustrative and not restrictive. The scope of the present invention is as set forth in the appended claims rather than being limited to the examples set forth in the foregoing description. Any and all equivalents are intended to be embraced by the claims.
Claims
1. A process for forming a cobalt conversion coating on a metal substrate, said process comprising the steps of:
(a) providing a cobalt conversion solution comprising an aqueous solution comprising a soluble cobalt-III hexavalent complex, the concentration of said cobalt-III hexavalent complex being from about 0.01 mole per liter of solution to the saturation limit of said cobalt-III hexavalent complex; and
(b) contacting said substrate with said solution for a sufficient amount of time, whereby said cobalt conversion coating is formed.
2. The process of Claim 1 wherein said cobalt-III hexavalent complex is present in the form of Mem[Co(R)6Jn wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms.
3. The process of Claim 2 wherein R is acetate.
4. The process of Claim 1 wherein the concentration of said cobalt-III hexavalent complex is from about 0.04 mole per liter of solution up to about 0.15 mole per liter of solution.
5. The process of Claim 1 wherein said cobalt conversion solution has a pH ofabout 5.0 to 9.0.
6. The process of Claim 1 wherein said cobalt conversion solution has a temperature of about 68 °F to 160°F.
7. The process of Claim 1 wherein said substrate is contacted with said cobalt conversion solution for a time of about 3 minutes to 60 minutes.
8. An article produced by the process of Claim 1.
9. A process for forming a cobalt conversion coating on a metal substrate, said process comprising the steps of:
(a) providing a cobalt conversion solution comprising an aqueous solution comprising a soluble cobalt-III hexacarboxylate complex, the concentration
of said cobalt-III hexacarboxylate complex being from about 0.01 mole per liter of solution to the saturation limit of said cobalt-III hexacarboxylate complex; and
(b) contacting said substrate with said solution for a sufficient amount of time, whereby said cobalt conversion coating is formed.
10. The process of Claim 8 wherein said cobalt-III hexacarboxylate complex is present in the form of Mem[Co(R)6Jn wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 1 or 2, n is 2 or 3, and R is a carboxylate having from 1 to 5 C atoms.
11. The process of Claim 9 wherein R is acetate.
12. The process of Claim 8 wherein the concentration of said cobalt-III hexacarboxylate complex is from about 0.04 mole per liter of solution up to about 0.15 mole per liter of solution.
13. The process of Claim 8 wherein said cobalt conversion solution has a pH ofabout 5.0 to 9.0.
14. The process of Claim 8 wherein said cobalt conversion solution has a temperature of about 68 °F to 160°F.
15. The process of Claim 8 wherein said substrate is contacted with said cobalt conversion solution for a time of about 3 minutes to 60 minutes.
16. An article produced by the process of Claim 8.
17. A process for forming a cobalt conversion coating on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:
(a) providing a cobalt conversion solution comprising an aqueous solution comprising a soluble cobalt-III hexavalent complex, the concentration of said cobalt-III hexavalent complex being from about 0.01 mole per liter of solution up to the saturation limit of said cobalt-III hexavalent complex; and
(b) contacting said substrate with said solution for a sufficient amount of time, whereby said cobalt conversion coating is formed.
18. The process of Claim 15 wherein said cobalt-III hexavalent complex is present in the form of Mem[Co(R)6]n wherein Me is one or more selected from the
group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms.
19. The process of Claim 16 wherein R is acetate.
20. The process of Claim 15 wherein the concentration of said cobalt-III hexavalent complex is from about 0.04 mole per liter of solution up to about 0.15 mole per liter of solution.
21. The process of Claim 15 wherein said cobalt conversion solution has a pH ofabout 5.0 to 9.0.
22. The process of Claim 15 wherein said cobalt conversion solution has a temperature of about 68 °F to 160°F.
23. The process of Claim 15 wherein said substrate is contacted with said cobalt conversion solution for a time of about 3 minutes to 60 minutes.
24. An article produced by the process of Claim 15.
25. A process for forming a cobalt conversion coating on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:
(a) providing a cobalt conversion solution comprising a solution prepared by reacting a cobalt-II salt with a metal carboxylate having from 1 to 5 carbon atoms, wherein the concentration of said cobalt-II salt is from about 0.04 mole per liter of final solution up to about 0.15 mole per liter of final solution, and the concentration of metal carboxylate is from about 0.03 to 2.5 mole per liter of final solution; and
(b) contacting said substrate with said solution for a sufficient amount of time, whereby said cobalt conversion coating is formed.
26. The process of Claim 22 wherein said cobalt-II salt is a cobalt-II salt which has a minimum solubility of about 0.01 moles of cobalt-II salt per liter of water at 20°C (68°F).
27. The process of Claim 22 wherein said cobalt-II salt is cobalt acetate.
28. The process of Claim 22 wherein said cobalt conversion solution is prepared by a bath makeup sequence comprising:
(a) dissolving said metal carboxylate salt; and
(b) then adding said cobalt-II salt.
29. The process of Claim 22 wherein said cobalt conversion solution has a pH ofabout 5.0 to 9.0.
30. The process of Claim 22 wherein said cobalt conversion solution has a temperature of about 68°F to 160°F.
31. The process of Claim 22 wherein said substrate is contacted with said cobalt conversion solution for a time of about 3 minutes to 60 minutes.
32. An article produced by the process of Claim 22.
33. A chemical conversion coating solution for producing a cobalt conversion coating on a metal substrate, said solution comprising an aqueous solution comprising a soluble cobalt-III hexavalent complex, the concentration of said cobalt- III hexavalent complex being from about 0.01 mole per liter of solution to the saturation limit of said cobalt-III hexavalent complex.
34. The solution of Claim 33 wherein said cobalt-III hexavalent complex is present in the form of Mem[Co(R)g]n wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms.
35. A chemical conversion coating solution for producing a cobalt conversion coating on a metal substrate, said solution comprising:
(a) an aqueous solution comprising a soluble cobalt-III carboxylate complex, the concentration of said cobalt-III carboxylate complex being from about 0.01 mole per liter of solution up to the saturation limit of said cobalt-III carboxylate complex;
(b) wherein said solution is prepared by reacting a cobalt-II salt with a metal carboxylate salt having from 1 to 5 C atoms, wherein the concentration of said cobalt-II salt is from about 0.01 mole per liter of final solution up to the saturation limit of the cobalt-II salt employed, the concentration of said metal carboxylate salt is from about 0.03 to 2.5 mole per liter of final solution.
36. The solution of Claim 35 wherein said cobalt-II salt is a cobalt-II salt which has a minimum solubility of about 0.01 mole of cobalt-II salt per liter of water at 20°C (68°F).
37. The solution of Claim 35 wherein said cobalt-II salt is cobalt acetate.
38. The solution of Claim 35 wherein said metal is selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn.
39. The solution of Claim 38 wherein said metal carboxylate is a metal acetate.
40. The solution of Claim 37 wherein said cobalt conversion solution is prepared by a bath makeup sequence comprising:
(a) dissolving said metal carboxylate; and
(b) then adding said cobalt-II salt.
41. The solution of Claim 37 wherein said solution has a pH of about 5.0 to 9.0.
42. The solution of Claim 37 wherein said solution has a temperature of about 68 °F to 160 °F.
43. A chemical conversion coating solution for producing a cobalt conversion coating on a substrate, wherein said substrate is aluminum or aluminum alloy, said solution comprising an aqueous solution comprising a soluble cobalt-III hexavalent complex, the concentration of said cobalt-III hexavalent complex being from about 0.01 mole per liter of solution to the saturation limit of said cobalt-III hexavalent complex.
44. The solution of Claim 43 wherein said cobalt-III hexavalent complex is present in the form of Mem[Co(R)6]n wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms.
45. „ A chemical conversion coating solution for producing a cobalt conversion coating on a substrate, wherein said substrate is aluminum or aluminum alloy, said solution comprising:
(a) an aqueous solution comprising a soluble cobalt-III hexacarboxylate complex, the concentration of said cobalt-III hexacarboxylate complex being from about 0.01 mole per liter of solution to the saturation limit of said cobalt-III hexacarboxylate complex;
(b) wherein said solution is prepared by reacting a cobalt-II salt with a metal carboxylate having from 1 to 5 C atoms, wherein the concentration of said cobalt-II salt is from about 0.01 mole per liter of final solution up to the saturation limit of the cobalt-II salt employed, and the concentration of metal carboxylate is from about 0.03 to 2.5 mole per liter of final solution. '
46. The solution of Claim 45 wherein said cobalt-II salt is a cobalt-II salt which has a minimum solubility of about 0.01 moles per liter of water at 20°C (68°F).
47. The solution of Claim 45 wherein said cobalt-II salt is cobalt acetate.
48. The solution of Claim 45 wherein said cobalt conversion solution is prepared by a bath makeup sequence comprising the steps of:
(a) dissolving said metal carboxylate; and
(b) then adding said cobalt-II salt.
49. The solution of Claim 45 wherein said solution has a pH of about 5.0 to 9.0.
50. The solution of Claim 45 wherein said solution has a temperature of about 68 °F to 160°F.
51. A coated article exhibiting corrosion resistance and paint adhesion properties, said article comprising:
(a) a metal substrate; and
(b) a cobalt conversion coating formed on said substrate, said cobalt conversion coating comprising aluminum oxide Al2O3 as the largest volume percent, and one or more cobalt oxides from the group consisting of CoO, Co2O3 and C03O4.
52. The coated article of Claim 51 wherein:
(a) in the portion of said cobalt conversion coating adjacent said substrate, the largest volume percent of said coating consists essentially of Al2O3;
(b) in the top portion of said cobalt conversion coating, the largest volume percent of said coating consists essentially of a mixture of Co2O3 and C03O4; and
(c) in the portion of said cobalt conversion coating therebetween, said coating consists essentially of a mixture of CoO, Co2O3, C03O4, and Al2O3.
53. The article of Claim 51 wherein said cobalt conversion coating has a coating weight of about 20 to 240 mg/ft2.
54. The article of Claim 51 wherein the top of said cobalt conversion coating is porous and has the appearance of sponge as shown in FIGURES 1 through 4.
55. A coated article exhibiting corrosion resistance and paint adhesion properties, said article comprising:
(a) a substrate, said substrate being aluminum or aluminum alloy; and
(b) a cobalt conversion coating formed on said substrate, said cobalt conversion coating comprising aluminum oxide Al2O3 as the largest volume percent, and one or more cobalt oxides from the group consisting of CoO, Co2O3, and C03O4.
56. The coated article of Claim 55 wherein:
(a) in the portion of said cobalt conversion coating adjacent said substrate, the largest volume percent of said coating consists essentially of Al2O3;
(b) in the top portion of said cobalt conversion coating, the largest volume percent of said coating consists essentially of a mixture of Co2O3 and C03O4; and
(c) in the portion of said cobalt conversion coating therebetween, said coating consists essentially of a mixture of CoO, Co2O3, C03O4, and Al2O3.
57. The article of Claim 55 wherein said cobalt conversion coating has a coating weight of about 20 to 240 mg/ft2.
58. The article of Claim 55 wherein the top of said cobalt conversion coating is porous and has the appearance of sponge as shown in FIGURES 1, 2, 3 and 4.
59. A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:
(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution prepared by reacting cobalt acetate with a metal acetate selected from the group consisting of Mg, Ca, and Na acetate, wherein the concentration of said cobalt acetate is about 30 to 35 grams per liter of final solution and the concentration of said metal acetate is about 65 to 130 grams per liter of final solution; and
(b) contacting said substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.
60. The process of Claim 59 wherein an alkyl fluoride or fluorocarbon wetting agent in the amount required to produce a liquid surface tension of 30 to 40 degrees per centimeter.
61. The process of Claim 59 wherein MgF2, CaF2 or mixtures thereof are added to said solution in an amount ranging from 2 to 4 grams per liter of final solution.
62. The process of Claim 59 wherein said cobalt conversion solution is prepared by a bath makeup sequence comprising:
(a) adding and dissolving said metal acetate;
(b) then adding and dissolving said cobalt acetate.
63. The process of Claim 59 wherein said cobalt conversion solution has a pH ofabout 6.0 to 7.0.
64. The process of Claim 59 wherein said cobalt conversion solution has a temperature of about 140 ± 5°F.
65. The process of Claim 59 wherein said substrate is contacted with said cobalt conversion solution for a time of about 5 minutes to 30 minutes.
66. The process of Claim 59 wherein the concentration of the cobalt acetate is 33 grams per liter of final solution and of metal acetate is 70 to 125 grams per liter of final solution.
67. A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:
(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution prepared by reacting cobalt acetate with a metal acetate selected from the group consisting of magnesium, calcium, and sodium acetate and mixtures thereof, wherein the concentration of said cobalt acetate is about 30 to 35 grams per liter of final solution and the concentration of said metal acetate is about 65 to 130 grams per liter of final solution; and
(b) contacting said substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.
68. The process of Claim 67 wherein said cobalt conversion solution is prepared by a bath makeup sequence comprising:
(a) adding and dissolving said metal acetate;
(b) then adding and dissolving said cobalt acetate.
69. The process of Claim 67 wherein said cobalt conversion solution has a pH of about 6.0 to 7.5.
70. The process of Claim 67 wherein said cobalt conversion solution has a temperature of about 140 ± 5°F.
71. The process of Claim 67 wherein said substrate is contacted with said cobalt conversion solution for a time of about 15 minutes to 25 minutes.
72. A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum or aluminum alloy, said process comprising the steps of:
(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution of a soluble cobalt-III hexacarboxylate complex, wherein said cobalt-III hexacarboxylate complex is present in the form of Mem[Co(R)6Jn wherein Me is one or more selected from the group consisting of Na, Li, K, Ca, Zn, Mg and Mn, and wherein m is 2 or 3, n is 1 or 2, and R is a carboxylate having from 1 to 5 C atoms, and wherein said cobalt-III hexacarboxylate complex was made by reacting a cobalt-II carboxylate salt with a metal carboxylate such that the concentration of said cobalt-III hexacarboxylate complex is from about 0.1 mole per gallon of solution to the solubility limit of said cobalt-III hexacarboxylate complex; and
(b) contacting said metal substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.
73. The process of Claim 72 wherein said cobalt conversion solution has a pH ofabout 6.0 to 7.0.
74. The process of Claim 72 wherein said cobalt conversion solution has a temperature of about 135 °F to 145 °F.
75. The process of Claim 72 wherein said substrate is contacted with said cobalt conversion solution for a time of about 3 minutes to 60 minutes.
76. A process for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, wherein said substrate is aluminum, aluminum alloy, magnesium, magnesium alloy, a Cd plated substrate, or a Zn-Ni plated substrate, said process comprising the steps of:
(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution prepared by reacting a cobalt-II salt with a metal carboxylate salt, wherein the concentration of said cobalt-II salt is from about 0.1 moles per gallon of final solution to the solubility limit of the cobalt-II salt employed and the concentration of said metal carboxylate salt is from about 0.03 to 2.5 moles per gallon of final solution; and
(b) contacting said substrate with said solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt
conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.
77. The process of Claim 76 wherein said cobalt-II salt is cobalt acetate.
78. The process of Claim 76 wherein the metal of said metal carboxylate is selected from the group consisting of Na, K, Li, Ca, Zn, Mg and Mn.
79. The process of Claim 76 wherein a fluorinated wetting agent is added to said cobalt conversion solution to assist in the formation of said Cobalt conversion coating on said substrate.
80. The process of Claim 76 wherein said wetting agent is selected from the group consisting of an alkyl fluoride, fluorocarbons, CaF2, MgF2) ancj mi tures thereof.
81. The process of Claim 76 wherein said cobalt conversion solution is prepared by a bath makeup sequence comprising:
(a) adding and dissolving said metal carboxylate;
(b) then adding and dissolving said cobalt-II salt.
82. The process of Claim 76 wherein said substrate is contacted with said cobalt conversion solution for a time of about 3 minutes to 60 minutes.
Priority Applications (12)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019940704721A KR100327142B1 (en) | 1992-06-25 | 1993-06-23 | Method for forming cobalt conversion coating on metal substrate, chemical conversion coating solution and article manufactured by the above method |
| AU45008/93A AU687740B2 (en) | 1992-06-25 | 1993-06-23 | Non-chromated oxide coating for aluminum substrates |
| EP93914728A EP0646187B1 (en) | 1992-06-25 | 1993-06-23 | Non-chromated oxide coating for aluminum substrates |
| DE69329853T DE69329853T2 (en) | 1992-06-25 | 1993-06-23 | NON-CHROMATED OXIDE COATINGS FOR ALUMINUM SUBSTRATES |
| BR9306602A BR9306602A (en) | 1992-06-25 | 1993-06-23 | Non-chrome oxide coating for aluminum substrates |
| JP50204994A JP3345010B2 (en) | 1992-06-25 | 1993-06-23 | Chromium-free oxide coating for aluminum support |
| DK93914728T DK0646187T3 (en) | 1992-06-25 | 1993-06-23 | Non-chromated oxide coating for aluminum substrates |
| AT93914728T ATE198631T1 (en) | 1992-06-25 | 1993-06-23 | NON-CHROMATED OXIDE COATINGS FOR ALUMINUM SUBSTRATES |
| RU94046218A RU2135637C1 (en) | 1992-06-25 | 1993-06-23 | Method of formation of coating from oxide of conversion cobalt, product, chemical solution for application of coating from conversion cobalt and coated article |
| CA002138790A CA2138790C (en) | 1992-06-25 | 1993-06-23 | Non-chromated oxide coating for aluminum substrates |
| NO19945026A NO315522B1 (en) | 1992-06-25 | 1994-12-23 | Process for preparing a cobalt-based coating on an aluminum substrate, as well as dissolving and using it in the manufacture of a cobalt-based coating |
| GR20010400395T GR3035554T3 (en) | 1992-06-25 | 2001-03-09 | Non-chromated oxide coating for aluminum substrates. |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/903,853 | 1992-06-25 | ||
| US07/903,853 US5411606A (en) | 1990-05-17 | 1992-06-25 | Non-chromated oxide coating for aluminum substrates |
| CNB931017378A CN1138873C (en) | 1992-06-25 | 1993-01-18 | Non-chromated oxide coating for aluminum substrates |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1994000619A1 true WO1994000619A1 (en) | 1994-01-06 |
Family
ID=36793885
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP1993/001630 WO1994000619A1 (en) | 1992-06-25 | 1993-06-23 | Non-chromated oxide coating for aluminum substrates |
Country Status (18)
| Country | Link |
|---|---|
| EP (1) | EP0646187B1 (en) |
| JP (1) | JP3345010B2 (en) |
| CN (2) | CN1138873C (en) |
| AT (1) | ATE198631T1 (en) |
| AU (1) | AU687740B2 (en) |
| BR (1) | BR9306602A (en) |
| CA (1) | CA2138790C (en) |
| DE (1) | DE69329853T2 (en) |
| DK (1) | DK0646187T3 (en) |
| ES (1) | ES2152950T3 (en) |
| GR (1) | GR3035554T3 (en) |
| MX (1) | MX9303745A (en) |
| NO (1) | NO315522B1 (en) |
| NZ (1) | NZ253699A (en) |
| RU (1) | RU2135637C1 (en) |
| SG (1) | SG43169A1 (en) |
| WO (1) | WO1994000619A1 (en) |
| ZA (1) | ZA934544B (en) |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996005335A1 (en) * | 1994-08-09 | 1996-02-22 | The Boeing Company | Improved non-chromated oxide coating for aluminum substrates |
| WO1996021753A1 (en) * | 1995-01-13 | 1996-07-18 | Henkel Corporation | Composition and process for forming a solid adherent protective coating on metal surfaces |
| WO1996029448A1 (en) * | 1995-03-22 | 1996-09-26 | Henkel Corporation | Compositions and processes for forming a solid adherent protective coating on metal surfaces |
| EP0826792A1 (en) * | 1996-09-02 | 1998-03-04 | Cfpi Industries | Bath and process for phosphating metal substrates, concentrates for preparing the bath and metal substrates treated according to the process |
| US5873953A (en) * | 1996-12-26 | 1999-02-23 | The Boeing Company | Non-chromated oxide coating for aluminum substrates |
| US5948178A (en) * | 1995-01-13 | 1999-09-07 | Henkel Corporation | Composition and process for forming a solid adherent protective coating on metal surfaces |
| US6315823B1 (en) | 1998-05-15 | 2001-11-13 | Henkel Corporation | Lithium and vanadium containing sealing composition and process therewith |
| FR2856079A1 (en) * | 2003-06-11 | 2004-12-17 | Pechiney Rhenalu | Surface treatment of aluminum alloy by preparation in a plasma atmosphere and treating in a metal salt bath using a no rinse technique, notably for motor vehicle fabrication operations |
| US7235142B2 (en) | 2002-01-04 | 2007-06-26 | University Of Dayton | Non-toxic corrosion-protection rinses and seals based on cobalt |
| US7291217B2 (en) | 2002-01-04 | 2007-11-06 | University Of Dayton | Non-toxic corrosion-protection pigments based on rare earth elements |
| US7294211B2 (en) | 2002-01-04 | 2007-11-13 | University Of Dayton | Non-toxic corrosion-protection conversion coats based on cobalt |
| CN104846309A (en) * | 2015-05-09 | 2015-08-19 | 安徽鼎恒再制造产业技术研究院有限公司 | A kind of high-strength Co3O4-SiC coating material and its preparation method |
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| ES2125231T3 (en) * | 1991-07-19 | 1999-03-01 | Boeing Co | NON-CHROME OXIDE COATINGS FOR ALUMINUM SUBSTRATES. |
| CN1309864C (en) * | 2004-09-29 | 2007-04-11 | 广州擎天油漆化工实业有限公司 | Environmental protective process for forming transforming film on aluminium and aluminium alloy surface |
| CN100372972C (en) * | 2005-11-03 | 2008-03-05 | 复旦大学 | Method for growing metal-organic complexes on solid surfaces |
| RU2416680C1 (en) * | 2009-11-05 | 2011-04-20 | Федеральное государственное образовательное учреждение высшего профессионального образования "Астраханский государственный технический университет" | Electrolyte of aluminium and its alloys anodic treatment |
| CN103184445A (en) * | 2011-12-28 | 2013-07-03 | 上海航天精密机械研究所 | Chemical oxidation solution composition for aluminium-alloy surface and chemical oxidation process |
| CN103266314B (en) * | 2013-05-31 | 2015-05-13 | 海安县申菱电器制造有限公司 | Method for treating aluminum alloy cobalt salt chemical conversion coating |
| CN103266315B (en) * | 2013-05-31 | 2015-05-13 | 海安县申菱电器制造有限公司 | Preparation of aluminum alloy cobalt salt chemical conversion coating treating fluid |
| CN106868495B (en) * | 2017-01-23 | 2019-06-11 | 江苏理工学院 | A kind of recovery and reuse method of cobalt salt chemical oxidation waste liquid |
| WO2020006365A1 (en) * | 2018-06-28 | 2020-01-02 | Nelumbo Inc. | Coincident surface modifications and methods of preparation thereof |
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- 1993-06-22 MX MX9303745A patent/MX9303745A/en unknown
- 1993-06-23 AU AU45008/93A patent/AU687740B2/en not_active Expired
- 1993-06-23 SG SG1996004772A patent/SG43169A1/en unknown
- 1993-06-23 RU RU94046218A patent/RU2135637C1/en not_active IP Right Cessation
- 1993-06-23 ES ES93914728T patent/ES2152950T3/en not_active Expired - Lifetime
- 1993-06-23 BR BR9306602A patent/BR9306602A/en not_active IP Right Cessation
- 1993-06-23 EP EP93914728A patent/EP0646187B1/en not_active Expired - Lifetime
- 1993-06-23 CA CA002138790A patent/CA2138790C/en not_active Expired - Fee Related
- 1993-06-23 NZ NZ253699A patent/NZ253699A/en not_active IP Right Cessation
- 1993-06-23 WO PCT/EP1993/001630 patent/WO1994000619A1/en active IP Right Grant
- 1993-06-23 DK DK93914728T patent/DK0646187T3/en active
- 1993-06-23 JP JP50204994A patent/JP3345010B2/en not_active Expired - Lifetime
- 1993-06-23 AT AT93914728T patent/ATE198631T1/en not_active IP Right Cessation
- 1993-06-23 DE DE69329853T patent/DE69329853T2/en not_active Expired - Fee Related
- 1993-06-24 ZA ZA934544A patent/ZA934544B/en unknown
- 1993-06-25 CN CNB931075831A patent/CN1195893C/en not_active Expired - Fee Related
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- 1994-12-23 NO NO19945026A patent/NO315522B1/en unknown
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| EP0458020A1 (en) * | 1990-05-17 | 1991-11-27 | The Boeing Company | Non-chromated oxide coating for aluminum substrates |
| EP0488430A2 (en) * | 1990-11-30 | 1992-06-03 | The Boeing Company | Non-chromated cobalt conversion coating |
| EP0523288A1 (en) * | 1991-07-19 | 1993-01-20 | The Boeing Company | Non-chromated oxide coating for aluminum substrates |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996005335A1 (en) * | 1994-08-09 | 1996-02-22 | The Boeing Company | Improved non-chromated oxide coating for aluminum substrates |
| WO1996021753A1 (en) * | 1995-01-13 | 1996-07-18 | Henkel Corporation | Composition and process for forming a solid adherent protective coating on metal surfaces |
| US5948178A (en) * | 1995-01-13 | 1999-09-07 | Henkel Corporation | Composition and process for forming a solid adherent protective coating on metal surfaces |
| US5843242A (en) * | 1995-03-22 | 1998-12-01 | Henkel Corporation | Compositions and processes for forming a solid adherent protective coating on metal surfaces |
| WO1996029448A1 (en) * | 1995-03-22 | 1996-09-26 | Henkel Corporation | Compositions and processes for forming a solid adherent protective coating on metal surfaces |
| US6068709A (en) * | 1996-09-02 | 2000-05-30 | Cfpi Industries | Bath and process for the phosphatization of metallic substrates, concentrates for the preparation of said bath and metallic substrates having been subjected to a treatment by said bath and process |
| FR2752851A1 (en) * | 1996-09-02 | 1998-03-06 | Cfpi Ind | BATH AND METHOD FOR PHOSPHATION OF METAL SUBSTRATES, CONCENTRATED FOR THE PREPARATION OF SUCH BATH, AND METALLIC SUBSTRATES TREATED WITH SUCH BATH AND METHOD |
| EP0826792A1 (en) * | 1996-09-02 | 1998-03-04 | Cfpi Industries | Bath and process for phosphating metal substrates, concentrates for preparing the bath and metal substrates treated according to the process |
| US5873953A (en) * | 1996-12-26 | 1999-02-23 | The Boeing Company | Non-chromated oxide coating for aluminum substrates |
| US6315823B1 (en) | 1998-05-15 | 2001-11-13 | Henkel Corporation | Lithium and vanadium containing sealing composition and process therewith |
| US7235142B2 (en) | 2002-01-04 | 2007-06-26 | University Of Dayton | Non-toxic corrosion-protection rinses and seals based on cobalt |
| US7291217B2 (en) | 2002-01-04 | 2007-11-06 | University Of Dayton | Non-toxic corrosion-protection pigments based on rare earth elements |
| US7294211B2 (en) | 2002-01-04 | 2007-11-13 | University Of Dayton | Non-toxic corrosion-protection conversion coats based on cobalt |
| US7407711B2 (en) | 2002-01-04 | 2008-08-05 | University Of Dayton | Non-toxic corrosion-protection conversion coats based on rare earth elements |
| US7422793B2 (en) | 2002-01-04 | 2008-09-09 | University Of Dayton | Non-toxic corrosion-protection rinses and seals based on rare earth elements |
| FR2856079A1 (en) * | 2003-06-11 | 2004-12-17 | Pechiney Rhenalu | Surface treatment of aluminum alloy by preparation in a plasma atmosphere and treating in a metal salt bath using a no rinse technique, notably for motor vehicle fabrication operations |
| WO2004111300A3 (en) * | 2003-06-11 | 2005-02-17 | Pechiney Rhenalu | Method for processing surfaces of aluminium alloy sheets and strips |
| CN104846309A (en) * | 2015-05-09 | 2015-08-19 | 安徽鼎恒再制造产业技术研究院有限公司 | A kind of high-strength Co3O4-SiC coating material and its preparation method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1090338A (en) | 1994-08-03 |
| CN1080963A (en) | 1994-01-19 |
| EP0646187A1 (en) | 1995-04-05 |
| NO945026L (en) | 1995-02-24 |
| ES2152950T3 (en) | 2001-02-16 |
| DE69329853T2 (en) | 2001-04-26 |
| RU2135637C1 (en) | 1999-08-27 |
| EP0646187B1 (en) | 2001-01-10 |
| CN1195893C (en) | 2005-04-06 |
| SG43169A1 (en) | 1997-10-17 |
| DE69329853D1 (en) | 2001-02-15 |
| BR9306602A (en) | 1998-12-08 |
| CA2138790C (en) | 2004-10-19 |
| JP3345010B2 (en) | 2002-11-18 |
| AU4500893A (en) | 1994-01-24 |
| ATE198631T1 (en) | 2001-01-15 |
| NO945026D0 (en) | 1994-12-23 |
| JPH07508311A (en) | 1995-09-14 |
| CA2138790A1 (en) | 1994-01-06 |
| AU687740B2 (en) | 1998-03-05 |
| ZA934544B (en) | 1994-03-18 |
| NO315522B1 (en) | 2003-09-15 |
| NZ253699A (en) | 1997-05-26 |
| DK0646187T3 (en) | 2001-04-30 |
| MX9303745A (en) | 1994-02-28 |
| CN1138873C (en) | 2004-02-18 |
| RU94046218A (en) | 1996-10-20 |
| GR3035554T3 (en) | 2001-06-29 |
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