JPS5873762A - Coated sinteredhard alloy and its production - Google Patents

Abstract

PURPOSE:To improve abrasion resistance, melt sticking resistance and chemical reaction resistance markedly by coating HfC on base bodies wherein a B-1 type solid soln. is enriched. CONSTITUTION:The sinteredhard alloy parts wherein WC and a B-1 type solid soln. are bound as a hard phase by ferrous metals are held for 10min-5hr at 1,200-1,600 deg.C in an atmospher of 1-700 Torr partial pressure of N2. After cooling HfC is coated to about 6 micron thickness on the surface of said parts by subjecting the parts to a chemical vapor deposition treatment using gaseous HfI4, C4H10. Then the content of Co in the parts at least at 1mu depth from the surface is <=20% basing on the content of Co at the sufficiently inner parts and 40-80vol% B-1 type solid soln. is contained.

Description

[Detailed description of the invention] The present invention relates to coated cemented carbide parts.

Cemented carbide &:Hfoi! The coated cemented carbide that has been tested with a solid coating has excellent wear resistance, welding resistance, and chemical reaction resistance, and is widely used in practical applications. However, the adhesion strength between the substrate and the film is not yet sufficient, and there are many limitations from a practical standpoint, such as the finish being unusable and not being suitable for use with cutters. This adhesive strength is affected not only by the physical and chemical bond between the substrate and the coating material, but also by differences in thermal expansion during cutting. In addition, particularly when chemical vapor deposition is used as a surface testing method, a decarburized phase called an eta phase is generated on the substrate immediately below the coating, reducing the interfacial strength. For this reason, various plans for improving the interface strength have been studied to date. Attempts have been made to increase the chemical bonding strength by reducing the content of d, ie, 00 metal, or to bring the thermal expansion coefficients of the substrate and film closer to each other by increasing the MbO content.

In addition, in order to prevent the occurrence of the eta phase, a method called carburizing treatment is used in which 0 is diffused from the substrate surface using a mixed gas of OHa + H* before the test treatment to prevent the generation of the eta phase. It will be done.

However, the reality is that these methods are not sufficiently effective. The reason for this is that Oo in the base cannot be reduced below a certain amount from the viewpoint of toughness, or in the case of carburizing, the processing time is too long! ! This is because, in addition to the long time of ~4 hours, it is necessary to adjust the amount of carburization to 0 by adjusting the content of the base material, which is difficult in practice. The objective is to provide a new coated cemented carbide that improves the adhesive strength between the material and the coating and has excellent thermal shock resistance and mechanical toughness.

The feature of the present invention is that Oo is hardly present on the surface of the cemented carbide substrate, and Hfo is directly coated on one surface of the substrate using a substrate enriched with B-1 type solid solution carbide phase. The -1 type solid solution is a compound with an HhOL type crystal structure consisting of one or more of the expanded products and nitrides of metals in groups 4m, 5a and 6a of the periodic table. A method of obtaining such a substrate is possible by adjusting the partial pressure of M1 in the sintering atmosphere, as is known in Japanese Patent Application Laid-Open No. 55-154561. By making the M1 partial pressure of the sintering atmosphere larger than the equilibrium M and partial pressure of the solid solution, B-
Due to the wettability relationship between the type 1 solid solution and the n-gold phase, there is almost no Oo present on the surface, and the surface is almost completely covered by the -1 type solid solution.

An important point of the present invention is that HfO is applied to a substrate enriched with B-, IM solid solution on the surface, and this
o@ or zrO'st - This is an excellent point that should be distinguished from the above-mentioned special feature - 154561/1983, which was characterized by direct coating.

First, the reason why the present invention is superior to the conventional carbide-coated W1 cemented carbide is that the eta phase, which is a filtration phase, does not occur when chemical coating treatment is performed.
@I can't avoid life. However, in the present invention 7, the base surface -〇-
``Enriched with 9 solid solution'': !' Because the 1-1 type 1-solid solution has a wide range of bonding ratio of 0, even if 0 in the B-1 phase diffuses into the film, the eta, which is a decarburized phase, is No phase is generated.The difference in thermal expansion coefficient between the B-1 type solid solution and the carbide film is smaller than that between the substrate and the expanded film, so there is little peeling of the film during cutting.Thirdly, the δ-form - Due to the absence of Oo at the film interface, the interfacial strength increases and the 00 from the substrate to the film increases.
Since there is no diffusion of , the abrasion resistance of the film is significantly improved.

Next, A directly onto the substrate whose surface is enriched with B-1 solid solution
Compared to the case of covering 40 m, when kt=o=B-, W in the type 1 solid solution and ALBO@ cause a chemical reaction, and a very brittle W oxide is formed at the interface. deteriorates. On the other hand, no embrittlement reaction phase occurs in the case of HfO coating. In this regard, the previously cited Unexamined Patent Application @aa-15
4561 (Here, the reason why the amount of B-'1 solid solution near the substrate surface was set at least 40 volume iii% is that if it is less than 40%, the eta phase will occur when chemical test treatment is performed. This may occur, and the difference in thermal expansion between the substrate and the coating is not sufficiently reduced, and the peel strength during cutting cannot be improved. Further, the reason why 0oji near the surface of the substrate is set to be sufficiently less than go% of the 00 content inside is that if it exceeds 20%, the III adhesion strength with the film deteriorates, and the abrasion resistance of the film decreases.

Next, the reason why the area near the surface is defined as "at least 1 .mu." is that if it is less than that, eta phase i during cutting will occur.

The reason why the partial pressure was set at 1 to 700 Tqrr when enriching the B-1 type solid solution on the substrate surface is that the effect is not sufficient below ITOrr (if it exceeds ?0OTorr, the surface roughness deteriorates, TiO is not suitable for the test carbide member.The reason why the temperature was limited to 1200C-1600C is that the carbide in the base will grow grains at temperatures exceeding 1600'C, making it unsuitable for practical use. This is because the effect of M-gas is not sufficient at this temperature.

Example 1 Powders were blended into a composition of 72WO-10Tio -10Tao -80o, sintered in vacuum at 1400C for 1 hour, then H and gas were introduced at 5 Torr, and the mixture was cooled to form a cemented carbide base (4). was created. Next, on this substrate, a chemical vapor deposition process was performed using Hf process 4.04H1 (+ gas) to coat l1lfo to a thickness of 6 μm.These two types were coated under the following cutting conditions: Work material: 80 M3 Cutting speed: 250 m /m 1n sending ri 04111/r
@ 7 depths of cut L5 It was impossible to cut if water-soluble cutting oil was used, but the depth of cut of the present invention is 30 degrees.
Example 2 '79WO-3TiO-3TiN-4TaO-2MbO
-9Go powder was mixed and sintered in vacuum at 1400 G for 1 hour, followed by 1 m of gas at 100 T o.
A cemented carbide substrate ((1)) was prepared by introducing r r and cooling in the furnace. At the same time, a substrate ψ without introducing nil gas was prepared as a comparison material.
Chemical vapor deposition treatment is performed using 4H1O gas to remove HfO6.
It was coated to a thickness of μm. Next, when the cross sections of these 2 g were observed, no eta phase was observed in (0), but eta phase was observed in φ) over a thickness of 2 to 3 μm just below the surface of the substrate. In addition, these 21 m were cut under the following interrupted cutting conditions: cutting speed 200 m/1ll
ill send ri α4 fable m/
r ev cutting depth 15118 Work material 80M3 Cutting was performed with a 101111 groove.

The comparison product CD) chip was damaged by an impact of 15Fg1, but the chip (0) of the present invention did not break even after 500 impacts. By coating a solid solution-enriched cemented carbide substrate with HfO, it is possible to prevent the generation of eta phase and obtain a coated cemented carbide that is resistant to thermal shock and mechanical shock.

't! ? Chief Minister Heo's Palace Display of incidents 1981 Patent Application No. 1'7 $329.

511'JI, (7) Name: Coated cemented carbide and its manufacturing method.

Taihachino (Nori Furukawano, Osamu Furukawa) makes supplementary notes.
Person'4'fIi', +E (1) If",,jm*."
□1. 5. ”. .

and "Detailed Description of the Invention" - Contents of Amendment 1 The statement in the "Claims" column of the specification is corrected as follows.

"HWO and B-1 type solid solution are used as a hard phase, and this is bonded with an iron group metal to form a hard alloy coated with Hl-0. In this case, from the surface of the cemented carbide in contact with the At a depth of at least 1μ, the 00 content is less than 20% of the Oo content well inside the cemented carbide, and the B-1 type solid solution is more than 40% by volume or more than 80% by volume.
1. A cemented carbide, characterized in that it contains less than t%.

2. Before applying and spreading HfO on the surface of a cemented carbide part in which WO and B-1 type solid solution are used as a hard phase and bonded with iron group metal paulownia, the said cemented carbide part is heated in advance by an amount of h. pressure is 1
~12oOC~1600C in ~700 TorrO atmosphere
A method for producing a coated cemented carbide, characterized by holding the coated cemented carbide for 10 minutes to 5 hours. ” Seal The statement marked “−” in “Detailed Description of the Invention” in the specification is corrected as follows.

(Insert "No improvement." in Specification I, Line 5B, Line 17, "Also, if it exceeds 80% by volume, the surface of the substrate becomes brittle, which is undesirable.")

(2) Insert the following sentence after "Produced." on page 6, line 15 of the same book.

``Also, as a comparative material, a cemented carbide substrate without introducing Mm gas was also produced.

The abundance ratio of each phase on these surfaces was as shown in the table below.

Table 1 (3) "On this substrate" in the same page of the same book is corrected to "on these substrates."

(4) Insert the following sentence after "Produced." on page 7, line 14 of the same book.

Note □ ``The composition ratio of each phase on both surfaces was as shown in the table below.

Table 2 that's all \;

Claims (1)

[Claims] L WO and ys-1 type solid solution il! In a coated cemented carbide made by coating a cemented carbide bonded with an iron group metal with H2, the surface of the cemented carbide in contact with the test film is placed at least 1 μ deep from the surface of the cemented carbide, and 00-containing The amount is 20% of the 00 content sufficiently inside the cemented carbide.
Coated cemented carbide 0&To and B-
1m! A test film of V was applied to the surface of a cemented carbide part made of a solid solution as a hard phase and bonded with an iron group metal. In advance, the partial pressure of N on the cemented carbide parts is l IJlooT
A method for producing a coated cemented carbide, characterized by holding the coated cemented carbide at IJiloo U N1600 C for 10 minutes to 6 hours in an atmosphere of orr.