JPS6248751B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a coated cemented carbide and a method for producing the same, and more particularly to a coated cemented carbide used as a coated tool for high-speed cutting and a method for producing the same. (Conventional technology) Cemented carbide is used as a base material, and TiC and TiC are coated on the surface of the base material.
Coated cemented carbide coated with TiCN, TiN, Al ₂ O ₃ , etc. in a single layer or in multiple layers has both the toughness of the base material and the wear resistance, heat resistance, and chemical reaction resistance of the hard surface layer. It has excellent performance as a tool material. (Problems to be solved by the invention) In recent years, as cutting speeds have increased, tool materials, etc. are required to have higher wear resistance.
Furthermore, it is desired to develop a tool material that does not impair its versatility. When a coated cemented carbide with a cemented carbide base material is used as a cutting tool material, for example, when cutting carbon steel at a high cutting speed of 300 m/min or more, the cutting edge temperature will rise to the liquidus temperature of the cemented carbide ( (approximately 1300℃), the plasticity and deformability of the cutting edge deteriorates due to the softening of the alloy (i.e., plastic deformation occurs), and the wear resistance decreases significantly, making it unusable in a short period of time. The current situation is that no matter how thick the Al ₂ O ₃ or TiC film is made, no effect can be expected. For this reason, coated tool materials using cermets or ceramics as a base material, which have better heat resistance, have also been developed. However, the toughness of cermets and ceramics is much lower than that of cemented carbide, so they cannot be used as general-purpose tools. For example, in high-speed cutting exceeding 300 m/min, Al ₂ O ₃ or Al ₂ O ₃ -TiC ceramic tools are used, but they are mainly used in finishing cutting with small feeds and small depths of cut. These tool materials lack toughness and cannot be used when the feed rate is high or the depth of cut is large. Recently, SiN ₄ -based tool materials have also been developed, but SiN ₄ is highly reactive with steel, so it cannot be used in ordinary steel cutting. A tool material in which SiN ₄ is used as a base material and the surface is coated with Al ₂ O ₃ has also been developed, but this does not go beyond the scope of SiN ₄ tools and cannot be said to be satisfactory. It can be said that cemented carbide is still an excellent base material that has both wear resistance and toughness required as a base material for coated cutting tools. However, when used for high-speed cutting, there is a problem of deterioration in plastic deformation resistance due to its lower liquidus temperature than the aforementioned ceramics. The present invention solves the above problems and provides a coated cemented carbide that uses a cemented carbide with excellent plastic deformation resistance as a base material, can be cut at high speed, and does not impair its versatility, and a method for manufacturing the same. The coated cemented carbide of the present invention can be used as an excellent high speed cutting tool material. (Means for Solving the Problems) The present invention provides a cemented carbide having WC as a hard phase and one or more iron group metals as a binder phase. The base material is a cemented carbide formed by precipitating double carbides mainly composed of WC and Co, and the surface of the base material is coated with metals from groups A, A, and A of the periodic table, and metals from the group consisting of Al, Si, and B. One or more selected types and C, B, N,
The present invention relates to a coated cemented carbide having a coating composed of one or more selected from the group consisting of O. In addition, the present invention provides a method for coating the surface of a cemented carbide base material with WC as a hard phase and one or more iron group metals as a binder phase using hydrocarbons, N ₂ , and NH _{3 .} Or in a gas atmosphere of CO gas, under reduced pressure of 1 to 300 torr, at a temperature of 900 to
Heating to 1100℃, thereby removing 1 from the surface of the base material.
At ~100 μm, double carbides consisting of WC and one or more iron group metals, such as Co, disappear, and at 1 to 100 μm from the surface of the cemented carbide.
A cemented carbide base material is prepared by precipitating a double carbide consisting of WC and one or more of the iron group metals, such as Co, within micrometers, and then the surface of the base material is coated with the elements a, a, A group metal, Al,
one or more selected from the group consisting of Si, B, and C,
The present invention also provides a method for manufacturing a coated cemented carbide, which comprises forming a coating composed of one or more selected from the group consisting of B, N, and O. In the present invention, the saturation magnetic amount of a cemented carbide containing Co as a binder phase is expressed as a ratio to the Co binder phase amount, and is expressed as 12<saturation magnetic amount (Gauss/cm ³ /g)/Co binder phase amount. (% by weight) It is particularly preferable that the amount is in the range of 16. (Function) The present invention makes the amount of bonded carbon in the cemented carbide significantly lower than the theoretical amount of bonded carbon in the cemented carbide, and the alloy contains one or more iron group metals called η phase and W. Double carbides (Co ₃ W ₃ C, Co ₆ W ₆ C,
The above-mentioned problems are solved by the presence of Ni ₃ W ₃ C, Ni ₆ W ₆ C, Fe ₃ W ₃ C, Fe ₆ W ₆ C), thereby making it possible to use the cemented carbide as a base material. This improves the heat resistance of coated cemented carbide. It is well known that the alloy properties of cemented carbide vary significantly depending on the amount of carbon contained therein. Usually, a two-phase alloy consisting of a WC phase and a Co phase, or a Ti,
It has been put to practical use in the carbon content range where three-phase alloys consisting of a solid solution phase consisting of one or more of carbides, nitrides, and carbonitrides of Ta, Nb, Mo, W, and Cr exist. The reason for this is that it was previously thought that the appearance of the η phase would significantly reduce the strength, and for those skilled in the art, how to create an alloy in which the η phase does not appear is a major problem in terms of production technology. This was a problem, and only alloys in which the appearance of the η phase was suppressed as much as possible were put into practical use. The feature of the present invention is that, contrary to such conventional concepts, the η phase is intentionally made to appear inside the cemented carbide. As a result of a detailed study of the state of defects in coated cemented carbide members, the present inventors found that most of the defects and fractures in coated cemented carbide members occur in the very vicinity of the surface of the member (an area of 1 to 100 μm from the surface). We have obtained new knowledge that this is caused by a crack that originates from . Furthermore, the present discoverers found that although the toughness of cemented carbide in which the η phase coexists is slightly inferior to that of alloys in which the η phase does not appear, the temperature at which the liquid phase appears is about 60°C.
It was also found that since the temperature is high, the plastic deformation resistance and heat resistance are better. Furthermore, if the η phase disappears in a region of 1 to 100 μm from the cemented carbide surface, even if the η phase exists inside the alloy, it will be possible to maintain the same toughness as a normal alloy, and in addition, the internal The present inventors have discovered that plastic deformation resistance and heat resistance are improved if the η phase is present, and the present invention has been achieved based on this finding. In the coated cemented carbide of the present invention, the cemented carbide used as the base material has a hard phase of one or more carbides and/or nitrides of one or more metals of Groups A, A, and A of the Periodic Table. , one or more iron group metals are used as a binder phase. The reason why the layer in which the η phase does not appear near the cemented carbide surface (η phase disappearing region) is set at 1 to 100 μm from the surface is because it is difficult to maintain toughness when the thickness of the η phase disappearing layer becomes thinner than 1 μm. This is because if the thickness exceeds 100 μm, the heat resistance will decrease. Preferably it is in the range of 5 to 50 μm. The amount of η-phase that appears varies depending on the amount of carbon in the alloy, but the amount of carbon in the cemented carbide matrix of the present invention is determined by the amount of Co bonding phase (wt%) in the alloy and the amount of saturation magnetism (4π
The preferred range is 14<saturation magnetic amount (Gauss/cm ³ /g)/Co binder phase amount (wt%) 16, expressed as a ratio of σ value). If it is less than 14, the amount of η phase in the alloy increases and the versatility decreases. Moreover, when the value exceeds 16, no η phase appears. In addition, in order to form a η-phase disappearing phase in a portion of 1 to 100 μm from the alloy surface of the base metal, the alloy is heated in an atmosphere of 900 to 100 μm in an atmosphere of hydrocarbon, N ₂ , NH ₃ gas, or CO gas before coating the alloy. Preferably, the heat treatment is carried out at 1100° C. under a reduced pressure of 1 to 300 torr. In this case 900
Below ℃, the disappearance effect is weak, and above 1100℃, the η phase disappears deep inside the alloy. or,
Below 1 torr, the disappearance effect is too weak, and above 300 torr, it is too effective. Naturally, this treatment for the disappearance of the η phase is carried out as part of the sintering process in which the alloy is turned into a sintered body from a powder compact, and a part of the sintered body is ground. Therefore, for example, the original purpose can be achieved even if the base material does not have the η phase disappearing layer only on the barbed surface. The coating layer used in the present invention is based on periodic table a, a
and a single layer or a mixture or compound consisting of a group a metal, one or more selected from the group consisting of Al, Si and B, and one or more selected from the group consisting of C, B, N and O. It is coated with one or more types. TiC, SiC,
If a hard material such as TiN or Al ₂ O ₃ is selected as the coating layer, wear resistance will be improved. Al ₂ O ₃ ,
If an oxide such as ZrO ₂ or TiO ₂ is used as a coating layer, the heat resistance will be significantly improved in conjunction with the heat resistance of the base material. Further, a composite layer such as a mixture or solid solution of TiC, TiN, Al ₂ O ₃ , ZrO ₂ or the like, or a layer formed by alternately laminating these layers may also be used. To form these coating layers, chemical vapor deposition methods such as chemical vapor deposition (CVD method), plasma CVD method, and optically excited CVD method may be used, or ion plating, ion mixing, ion beam deposition, etc. may be used. It may also be by physical vapor deposition. In addition, a hard carbon film or a hard BN film can be directly applied to the cemented carbide (base material) of the present invention, or TiC,
If SiC, TiN, Al ₂ O ₃ or amorphous BN is interposed as an intermediate layer and then coated, high-performance coated carbide has the advantages of heat resistance of the base material and high hardness of the coating layer. An alloy tool is obtained. (Effects of the Invention) The coated cemented carbide of the present invention has improved plastic deformation resistance and heat resistance compared to conventional alloys, maintains toughness similar to conventional alloys, and has high hardness.
It can be used as an excellent tool material that can withstand high-speed cutting for long periods of time. Furthermore, the uncoated cemented carbide base material itself is also excellent in its versatility as a tool material. The manufacturing method of the present invention is a method that can realize an excellent coated cemented carbide as described above. (Example) Example 1 A cemented carbide consisting of 95 wt% WC and 5 wt% Co, each with an alloy carbon content of 98.7 of the theoretical carbon content.
%, 99.0%, and 99.5% (A), (B), and (C). The respective saturation magnetic quantities 4πσ values were (A) 61, (B) 70, and (C) 85 (Gauss/cm ³ /g). These alloys (A) to (C) are heated to
After holding the temperature at 1000°C for 30 minutes in a CO gas atmosphere of 200 torr, TiC was deposited to a thickness of 3 μm on the surface in a gas consisting of 2% by volume of TiCl ₄ , 10% by volume of CH ₄ , and the balance was H ₂ at a temperature of 1000°C. was generated. Thereafter, in a gas consisting of 5% by volume _AlCl3 , 5% by volume _CO2 , and the balance _H2 , the temperature
Al ₂ O ₃ with a thickness of 5 μm was further produced at 1000°C. Looking at the cross-sectional structure of the alloy obtained in this way,
In (A), the region up to 45 μm from the surface was a two-phase region of WC-Co, and the interior beyond that was a three-phase region of WC phase, Co phase, and η phase (Co ₃ W ₃ C). (B) is also 40
It was in the two-phase region of WC-Co up to μm. No η phase appeared in (C), and it was a WC-Co two-phase alloy. A cutting test was conducted on the coating chips prepared by these (A) to (C) under the conditions shown in Table 1 below.

【table】 The test results are shown in Table 2.

[Table] Example 2 For a cemented carbide made of 95% by weight WC and 5% by weight Co, the alloy carbon content is 99.3% of the theoretical carbon content, and the saturation magnetic quantity 4πσ value/Co content ratio = 15.8, (a) CH ₄ of 100 torr each at a temperature of 1000℃
Heat treatment was performed in a gas atmosphere, (b) N ₂ atmosphere, and (c) NH ₃ atmosphere. Before the above treatment, the alloy consisted of WC phase, Co phase, and η phase up to the surface, but according to step (a), up to 80 μm from the surface was WC-
In the two-phase region of the Co phase, the interior beyond that is a three-phase alloy in which the η phase coexists, and according to the processes (B) and (C), 60μ
The region up to m was a two-phase region of WC-Co, and the interior beyond that was a three-phase region where the η phase coexisted. Example 3 The chip subjected to step (a) of Example 2 was coated with TiCN to a thickness of 3 μm and amorphous BN to a thickness of 1 μm using the plasma CVD method, and then coated with a hard BN film (hardness of 3000 Kg/mm ² ). When a cutting test was conducted under the same conditions as in Table 1,
It was possible to cut for up to 40 minutes.

Claims (1)

[Claims] 1. A cemented carbide having WC as a hard phase and one or more iron group metals as a binder phase,
Inside the cemented carbide from 1 to 100 μm from the surface
The base material is a cemented carbide formed by precipitating double carbide consisting of WC and one or more iron group metals, and metals from groups a, a, and a of the periodic table, Al, and Si are coated on the surface of the base material. , B, and one or more members selected from the group consisting of C, B, N, and O. 2 The iron group metal is Co, and the saturation magnetic amount of the alloy with Co as the binder phase is expressed as a ratio to the binder phase amount, and 12<saturation magnetic amount (Gauss/cm ³ /g)/Co bond Coated cemented carbide according to claim 1 in an amount (% by weight) of 16%. 3. Before coating the surface of a cemented carbide base material with WC as a hard phase and one or more iron group metals as a binder phase, hydrocarbons, N ₂ ,
In a gas atmosphere of either NH ₃ or Co gas, under a reduced pressure of 1 to 300 torr and heated to a temperature of 900 to 1100°C, the surface of the base material is heated to 1 to 100 μm from the surface of the base material.
In this case, the double carbide consisting of WC and one or more of iron group metals has disappeared, and within 1 to 100 μm from the surface of the cemented carbide, the compound consisting of WC and one or more of iron group metals has disappeared. A cemented carbide base material formed by precipitating double carbides is prepared, and then metals from groups A, A, and A of the periodic table and one or more metals selected from the group consisting of Al, Si, and B are applied to the surface of the base material. A method for producing a coated cemented carbide, comprising: forming a coating composed of one or more selected from the group consisting of C, B, N, and O. 4 The iron group metal is Co, and the saturation magnetic amount of the alloy with Co as the binder phase is expressed as a ratio to the binder phase amount, and 12<saturation magnetic amount (Gauss/cm ³ /g)/Co bond A method for producing a coated cemented carbide according to claim 3, wherein the amount (wt%) is in the range of 16%.