CN103276426A - Manufacturing method of corrosion-resistant and antibacterial oxide film stainless steel - Google Patents

Abstract

The invention discloses a method for manufacturing stainless steel with an anti-corrosion and antibacterial oxide film. The method is as follows: first passivate the stainless steel substrate to form a passivation film of 10-20nm; then process in an acidic solution to form a 200 ~500nm spinel oxide film; finally, the stainless steel is obtained after sealing and drying. The invention is anti-bacterial, anti-mildew, anti-fouling, anti-odor, anti-corrosion, can prevent precipitation of heavy metals, anti-light and anti-discoloration, high wear resistance, non-toxic, lower cost, and can be made into natural or colored stainless steel.

Description

A method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel

technical field

The invention relates to a method for manufacturing stainless steel with an oxide film, in particular to a method for manufacturing stainless steel with an anti-corrosion and antibacterial oxide film, and belongs to the technical field of metal surface treatment.

Background technique

In recent years, many advanced industrial countries have competed to develop antibacterial stainless steel products. Taking Japan, which produces the most new products, as an example, there are coated antibacterial stainless steel, alloy antibacterial stainless steel, composite antibacterial stainless steel and vacuum coating antibacterial stainless steel. There are some problems in these stainless steels, such as: the coating bonding force of coated antibacterial stainless steel is unstable, and it cannot be applied at high temperature. In long-term use, it will burst and peel off due to the difference in thermal expansion coefficient between the film and the metal substrate; alloy antibacterial stainless steel For example, copper-added stainless steel is not corrosion-resistant in some media, especially pitting corrosion is more serious. Silver-added antibacterial stainless steel increases product costs due to its high silver content, and the composition is not easy to be uniform. Antibacterial only works on the surface layer, and Discoloration of surface silver is also unavoidable; composite antibacterial stainless steel is complicated to manufacture, and the antibacterial effect of antibacterial copper sheet is not good; the cost of vacuum-coated antibacterial stainless steel is high, and the problem of discoloration of silver on the surface is also difficult to solve.

Contents of the invention

Purpose of the invention: Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for manufacturing an oxide-coated stainless steel with antibacterial, anti-mildew, corrosion resistance, reliable performance, low cost, and controllable color.

Technical solution: In order to realize the above-mentioned purpose of the invention, the technical solution adopted in the present invention is:

A method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel, the method is: first passivate the stainless steel substrate to form a layer of 10-20nm passivation film; then process in an acid solution to form a layer of 200-500nm Spar oxide film; finally, the stainless steel is obtained after sealing and drying.

The passivation treatment refers to the action in the HNO ₃ solution with a mass concentration of 3% and the H ₂ O ₂ solution with a mass concentration of 2%, with an anode voltage of 2-3 volts for 1-3 minutes. Through passivation, the chromium-poor area on the surface of stainless steel can be eliminated or reduced, and the Cr content is significantly increased (take the same stainless steel, without passivation treatment and passivation treatment respectively, by testing the peak composition of the stainless steel surface, the change of Cr content is shown below Table 1), so that when turning into oxidation, the spinel film Me _a Cr _b O _r with Cr as the core can be easily formed at the chromium-rich place (Me is the metal element, a, b, r are the valence of metal and oxygen The sum of the number), also can make more antibacterial inorganic metal elements Ag, _Ni , Co, Ce, etc. combined in the film, improve the antibacterial and antifungal effect.

Table 1

Atom% Wt% without passivation 17.90% 16.78%

Passivated 19.83% 18.82%

The preparation of the spinel oxide film is in an acidic solution, using alternating positive and negative alternating currents, the time for alternating positive and negative currents is 1 to 15 seconds in the positive direction and 1 to 15 seconds in the negative direction, and the current density is 5 ～150mA/dm ² , temperature 20～80℃, action for 3-20 minutes. The current waveform can be triangular or rectangular. The voltage depends on the determined current density. Oxidation time depends on film thickness and color.

The current density is 20-80 mA/dm ² , and the temperature is 20-50°C. This current density and temperature range produces natural stainless steel.

The current density is 60-120 mA/dm ² , and the temperature is 50-80°C. Under this current density and temperature range, colored stainless steel can be formed.

The sealing treatment refers to soaking in pure water with a pH of 6.5 to 7.5 and a temperature of 70 to 90° C. for 5 to 10 minutes.

The ratio per liter of the acid solution is: 300-500g of sulfuric acid, 120-250g of chromic anhydride, 1-10g of molybdenum salt, 2-10g of manganese sulfate, 5-20g of nickel sulfate, 5-20g of cobalt sulfate, and 0-20g of silver salt. 5g, 5-20g of cerium salt.

The molybdenum salt is (NH ₄ ) ₂ MoO ₄ or Na ₂ MoO ₄ .

The silver salt is AgNO ₃ or Ag ₂ SO ₄ .

The cerium salt is Ce(NO ₃ ) ₂ or CeSO ₄ . Cerium salt is a rare earth resource, which can catalyze the antibacterial effect of Ni and Ag.

Because the acidic solution contains Ni, Mo, Mn, Ag, Co plasma, Ni, Mo appear blue, Mn, Ag appear yellow, Co appear red, under certain conditions can form blue, yellow, brown or bronze color and other colors. Stainless steel, red, yellow and blue are the three elements of black, which can be made into black stainless steel after the three colors are superimposed.

It is disclosed in literature that the antibacterial effect is Ag>Co≥Ni≥Al≥Zn≥Cu=Fe, Ni>Cu>Co>Zn=Ag>Fe≥Al. _Ni , Co, Mo, and Cr also have good antibacterial, anti-mildew, deodorant, and anti-fouling effects. Considering the production cost, Ag and Ce can be added less or not, and they also have good anti-bacterial and anti-mold effects.

The principle of antibacterial, anti-mold, anti-odor, anti-fouling effect is:

_Ni , Co and Ag ions themselves have antibacterial properties, which can directly mutate the outer layer of bacteria to inactivate the bacteria, and the silver ions in a high oxidation state have a very high reduction potential, which can make the oxygen in the air and water activate Negatively charged atomic oxygen O ^- , activating water molecule H ₂ O to become negatively charged hydroxyl group OH ^- , O ^- and OH ^- can make the cell coat protein of bacteria, viruses and other microorganisms mutate, so that bacteria, viruses Inhibit growth and reproduction, and promote its inactivation, so it has a bactericidal function, and contains _Ni , Mo and other elements that can promote the functions of anti-mold and killing mold. In the same way, because of the effect of O ^- and OH ^- , the dirt attached to the wall can be removed, so that the dirt on the container wall and the surface of the workpiece is not easy to be removed. At the same time, it can make the sulfide and nitride in the air become acidic substances under the action of O ^- and OH ^- and be removed, so it can play the role of deodorization.

Beneficial effect: compared with prior art, the remarkable advantage of the present invention is:

1) The sample of the present invention is anti-bacterial, anti-mildew, anti-fouling, deodorant, corrosion-resistant, and can prevent the precipitation of heavy metals;

2) The sample of the present invention is light-resistant and anti-discoloration, and it does not change color after 2 years of sunlight irradiation and 28 days of continuous ultraviolet irradiation;

3) The sample of the present invention has strong processing performance, high wear resistance, can withstand 180-degree bending, deep drawing and molding processing, and has higher wear resistance and scratch resistance than the original body stainless steel, and can withstand a load of 500 grams. The rubber has been rubbed more than 200 times, and can withstand the characterization of a steel needle with a load of 120 grams. The wear resistance is measured by the falling sand test method. The quality of the falling sand is 1Kg, and the sample of the present invention can reach 4.9Kg;

4) The acute oral LO50 values of male and female mice in the mouse acute oral toxicity test were both greater than 15000 mg/Kg bwt, indicating that the test sample of the present invention belongs to the non-toxic grade;

5) The sample of the present invention first forms a passivation film and then forms an oxide film, which has strong adhesion, is not affected by high temperature and the thermal expansion coefficient of the matrix alloy, and is more reliable and firmer;

6) The invention uses nickel with lower price to exert antibacterial and antifungal effects, and the cost is lower than that of silver and cerium;

7) The present invention can control the temperature, current density and other parameters to make the finished stainless steel into natural color or color, which can better meet the needs of industrial diversification, and the formed color film, such as blue and black, fills the technical vacancy that is difficult to prepare in the industry, and Yellow, brown, bronze, etc. have excellent properties such as corrosion resistance, beautiful appearance, and prevention of heavy metal precipitation.

Detailed ways

The present invention will be further described below through specific embodiments. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some modifications and improvements can also be made, and these should also be regarded as belonging to the present invention. protection scope of the invention.

Example 1

Select 304 material stainless steel and 201 material stainless steel, respectively do unpassivation treatment and passivation treatment, passivation treatment first with a mass concentration of 3% HNO ₃ solution and a mass concentration of 2% H ₂ O ₂ solution, through a 2 volt Anodic current, hold at room temperature for 1 min. The treated stainless steel was placed in a mass concentration of 20% FeCl ₃ at a temperature of 30°C and soaked for 1 hour. After 1 hour, test the corrosion rate, corrosion rate (%) = (weight before corrosion - weight after corrosion) / (weight before corrosion) × 100%.

The test results are shown in Table 2.

Table 2

The results show that after passivation treatment, the corrosion rate of stainless steel is reduced and it is more corrosion-resistant.

Example 2

First use 3% HNO ₃ solution and 2% H ₂ O ₂ solution, pass an anode current of 3 volts, and keep at room temperature for 3 minutes. Then use the acid solution of A～F, and use the positive and negative alternating current to form the spinel oxide film under the certain current density, temperature and action time. Then soak in pure water with pH 7 and temperature 70°C for 10 minutes and take it out to dry naturally. See Table 3 for the contents of the components of solutions A to F.

table 3

The test results of the prepared samples are shown in Table 4.

Table 4

Evaluation of test results:

1. Corrosion resistance

Soak in 20% FeCl ₃ solution for 2 hours, if the weight loss does not exceed 5%, it is excellent, and if the weight loss does not exceed 10%, it is good. The corrosion resistance of the above samples is excellent.

2. Anti-heavy metal precipitation

Boil for 1 hour in an aqueous solution of 4% acetic acid in mass concentration, soak for 24 hours after cooling down to room temperature, and measure the content of Cr, Ni, Fe and other heavy metals. The amount of heavy metals precipitated from the above samples was all zero.

3. Antibacterial

Antibacterial testing was carried out on stainless steel sheets, and the results showed that the antibacterial rates of the above samples against Escherichia coli 8099 and Staphylococcus aureus ATCC6538 were as high as 99%.

4. Mildew resistance

Anti-mildew test is carried out on stainless steel sheets, and the bacteria used in the test are

bacteria Bacteria number Aspergillus niger AS3.4463 is equivalent to ATCC6275 Penicillium pinophilum AS3.745 ball hair shell AS3.4254 Viridans AS3.3987 Aureobasidium pullulans AS3.3984

After cultivating the sample made of the test piece for 28 days, observe the degree of mold growth, and the grading standard is

not long level 0

Trace growth (<10%) Level 1 Slight growth (≥10%～<30%) level 2 Moderate growth (≥30%～<60%) Level 3 Severe growth (≥60% to full coverage) level 4

The above-mentioned test pieces all reached grade 1 or grade 2 mildew resistance, that is, excellent grade.

5. Color and luster

The above test piece can control the color of the sample by adjusting parameters such as temperature, current density, alternating current conversion time, and action time, and the stainless steel produced has high gloss, which can meet the control and diversification needs of industrial production.

Claims (10)

1. A method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel, characterized in that: on the stainless steel substrate, passivation treatment forms a passivation film of 10-20nm; Spinel oxide film; finally, the stainless steel is obtained after sealing and drying. 2. the manufacture method of anticorrosion and antibacterial oxide film stainless steel as claimed in claim 1 _, is characterized in that: described passivation treatment refers to the HNO solution of mass concentration ₃ % and mass concentration 2% O ₂ solution In the process, the anode voltage is 2~3 volts for 1~3 minutes. 3. the manufacture method of anticorrosion and antibacterial oxide film stainless steel as claimed in claim 1 is characterized in that: the preparation of described spinel oxide film is in acidic solution, with the alternating current of positive and negative alternating, positive and negative current The alternation time is 1-15 seconds in positive direction, 1-15 seconds in negative direction, current density 5-150mA/dm ² , temperature 20-80℃, and action for 3-20 minutes. 4 . The method for manufacturing corrosion-resistant and antibacterial oxidized stainless steel according to claim 3 , wherein the current density is 20-80 mA/dm ² and the temperature is 20-50° C. 5 . The method for manufacturing corrosion-resistant and antibacterial oxidized stainless steel according to claim 3 , wherein the current density is 60-120 mA/dm ² and the temperature is 50-80° C. 6 . 6. The method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel according to claim 1, characterized in that: the sealing treatment refers to soaking in pure water with a pH of 6.5-7.5 and a temperature of 70-90°C for 5-10 minutes. minute. 7. The method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel as claimed in claim 1, characterized in that: the proportioning per liter of the acidic solution is: 300-500 g of sulfuric acid, 120-250 g of chromic anhydride, 1-250 g of molybdenum salt 10 g, manganese sulfate 2~10 g, nickel sulfate 5~20 g, cobalt sulfate 5~20 g, silver salt 0~5 g, cerium salt 5~20 g. 8 . The method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel according to claim 7 , wherein the molybdenum salt is (NH ₄ ) ₂ MoO ₄ or Na ₂ MoO ₄ . 9. The method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel according to claim 7, characterized in that: the silver salt is AgNO ₃ or Ag ₂ SO ₄ . 10. The method for manufacturing corrosion-resistant and antibacterial oxide film stainless steel according to claim 7, characterized in that: the cerium salt is Ce(NO ₃ ) ₂ or CeSO ₄ .