JPS60238483A - Coated hard metal - Google Patents

Abstract

PURPOSE:To develop the titled coated hard metal for cutting tools having excellent high-speed cutting properties by forming a thin layer of the carbide, boride, nitride, oxide, etc. of a specified metal on the surface of an ultrahard base material obtained by sintering WC added with Co as a binder. CONSTITUTION:A double carbide consisting essentially of WC and Co is deposited at the inside 1-100mu from the surface in a hard metal obtained by sintering ultrahard WC added with Fe-group metals such as Co as a binder. A single or a double layer of a metal such as Ti, Zr, Nb, Ta, Cr, Mo, W, etc., >=1 kind selected from a group of Al, Si and B, and >=1 kind consisting of C, B, N, and O is coated on the surface, and the obtained material is heated to 900-1,100 deg.C in a gaseous atmosphere of hydrocarbons, N2, NH3, CO, etc. at 1-300Torr pressure, and the coated base material having a hard coated layer cosisting of WC and the hard carbide, boride, nitride, and oxide of said elements and having saturation magnetization expressed by equation (1) can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coated cemented carbide, and more particularly to a coated cemented carbide used as a coated tool for high-speed cutting.

(Conventional technology) Tie on the surface of the base material using cemented carbide as the base material.

Coated cemented carbide coated with TiON, Tin, A403, etc. in a single layer or a laminated layer has both the toughness of the base material and the wear resistance, heat resistance, and chemical reaction resistance of the hard surface layer. (Problem to be solved by the invention) Recently, as cutting speeds have increased, tool materials have been required to have higher wear resistance. However, 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, carbon steel is cut at a cutting speed of 300 m.
When cutting at a high speed of / min or more, the temperature of the cutting edge reaches the liquidus temperature of the cemented carbide (approximately 1300℃)? As the alloy softens and weakens, the plasticity and deformability of the cutting edge deteriorates (in other words, plastic deformation occurs), resulting in a significant drop in wear resistance and making it unusable in a short period of time.
At present, even if the film thickness of C is increased, no effect can be expected.

For this reason, coated tool materials using cermets or ceramics as base materials, which have excellent heat resistance, have been developed. However, the toughness of cermets and ceramics is much lower than that of cemented carbide, and cannot be used as a general-purpose tool.

For example, in high-speed cutting angle 11 exceeding 300m/n1in, MBOS and A440. -TIC ceramic tools are used, but mainly for small finish cutting operations with small feeds and 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, SiN4-based tool materials have also been developed, but SiN is highly reactive with steel, so it cannot be used in ordinary steel cutting. A tool material using 81N4 as a base material and coated with Al403e on the surface has also been developed, but this too does not go beyond the range of SiN4 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 deterioration in plastic deformation resistance due to the lower liquidus temperature compared to the ceramics mentioned above.

The purpose of the present invention is to solve the above-mentioned problems and provide a coated cemented carbide that uses a cemented carbide with excellent plastic deformation resistance as a base material, is capable of high-speed cutting, and does not impair its versatility. year,
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 a WC6 hard phase and one or more iron group metals as a binder phase, from 1 to 100 μm from the surface of the cemented carbide. The base material is a cemented carbide in which double carbides mainly composed of WC and Co are precipitated, and the surface of the base material is made of metals from groups IVa, Va, and Vla of the periodic table, and the group consisting of At, Si, and B. The present invention relates to a coated cemented carbide having a coating composed of one or more selected from the group consisting of C, B, N, and O.

(Function) The present invention reduces the amount of bonded carbon in the cemented carbide into a double carbide (0o3W
3(!, 0O1lW6(!)) solves the above-mentioned problems, thereby improving the heat resistance of the coated cemented carbide having the cemented carbide as a base material.

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 is put into 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, Wb, Mo, W, and Or 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. Only alloys that minimized the appearance of the reed and η phases had been put into practical use.

The feature of the present invention is that it is contrary to such conventional concept.

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 (1 to 100 μm from the surface).
We have obtained new knowledge that the crack pressure is attributable to crack pressure originating in the area of

Furthermore, the present discoverers found that although cemented carbide in which the η phase coexists in the alloy has inferior toughness compared to alloys in which the η phase does not appear, its liquid phase appearance temperature is, on the contrary, approximately 60°C. It was also found that since the temperature is high, the plastic deformation resistance and heat resistance are better.

And the l phase in the region 1 to 100 μm from the cemented carbide surface? If it disappears, even if the η phase exists inside the alloy, it can maintain the same toughness as a normal alloy, and in addition, if the η phase exists inside the alloy, it will have good plastic deformation resistance and heat resistance. The present invention has been achieved based on the discovery that this can be improved.

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 group IVa, Va, and Ma of the periodic table. , one or more iron group metals are used as a binder phase.

The reason why the layer where the η phase does not appear near the cemented carbide surface (η phase disappearing region) is defined as a region 1 to 100 μm from the surface is as follows.
This is because if the thickness of the η phase disappearing layer becomes thinner than 1 μm, it is difficult to maintain toughness, and if it exceeds 100 μm, heat resistance decreases. It is preferably 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. ), and the range is preferable. If it is less than 14, the amount of η phase in the alloy becomes large and the versatility decreases. Further, when the value exceeds 16, no η phase appears.

In addition, in order to form a η-phase vanishing phase in a portion of 1 to 100 μm from the alloy surface of the base metal, the alloy is heated at 900 to 1100 μm in an atmosphere of hydrocarbon, N, NH3 gas, or CO gas before coating the alloy. Preferably, the heat treatment is carried out at a temperature of 1 to 300 torr. In this case, the disappearance effect is weak at temperatures below 900°C, and at temperatures above 1100°C, the η phase disappears deep inside the alloy. Also, the vanishing effect is too weak at 1 torr or less, and too effective at 300 torr or more.

As a matter of course, this treatment for the disappearance of the η phase is performed by sintering the alloy into a sintered body rather than a powder compact. l! By grinding a part of the sintered body, for example, the original purpose can be achieved even as a base material without η phase disappearance f61 only on the burnt surface.

The coating layer used in the present invention includes metals from groups IVa, Va, and Ma of the periodic table, one or more selected from the group consisting of At, Eli, and B, and the group consisting of O, B, N, and O. A single layer or a mixture or a compound consisting of one or more of the selected compounds may also be coated with one or more of the selected compounds.

If a hard cylindrical material such as Tie, SiO, TiN, or A/403 is selected as the coating layer, the wear resistance will be improved. A403. If an oxide such as ZrO2, 'rto, etc. is used as a coating layer, the heat resistance will be significantly improved in conjunction with the heat resistance of the base material.

Also, Tie, TiN, A403. It may also be a composite layer such as a mixture of ZrO2 or the like, a solid solution, or a layer in which these layers are alternately laminated.

Chemical vapor deposition method (OVD method) is used to form these coating layers.
, a plasma FOVD method, a photo-excited OVD method, or the like, or a physical vapor deposition method such as ion blasting, ion mixing, ion beam deposition, etc. may be used.

In addition, a hard carbon film or a hard BN film can be directly coated on the cemented carbide (base material) of the present invention using a ceramic or tie film.

If SiO, TiN, A4403, amorphous BN, etc. are interposed as an intermediate layer and coated,
With the advantages of heat resistance of the base material and high hardness of the coating layer,
A high-performance coated cemented carbide tool can be 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, so high-speed cutting pressure It can also be used as an excellent tool material that can withstand long periods of time. Furthermore, the uncoated cemented carbide base material itself is excellent in its versatility as a tool material.

(Example) Example 1 A cemented carbide consisting of 95% by weight Wa and 5% by weight Co, with different carbon contents (A), 03), (3 of ψ).
Created various types of alloys. Respective saturation magnetic quantity 4πσ value 1dCA) 61.03) 70, (C) 85 (Gauss/c
rn3/? )Met.

These alloys (A) to (0) were heated at a temperature of 1 in an OVD device.
3 at 000℃, CO gas atmosphere 20o torr
After holding for 0 minutes, TLC142 volume chi, 0H410 volume u
%, the balance being H2, at a temperature of 1000° C., a Tie') was formed on the surface to a thickness of 3 μm. After that, At*Os 5% by volume, CjO*5% by volume, remainder US
In a gas consisting of
A403 of m was produced.

Looking at the cross-sectional structure of the alloy thus obtained, (A) shows a We-Co two-phase region at the neck 45 μm from the surface, and the interior beyond that is a WC phase, CO phase, η phase (co3w, o
) was in the three-phase region. ) was also in the VC-Co two-phase region up to 40 μm.

In (0), no η phase appeared and it was a VC-C02 sum alloy.

A cutting test was conducted on the coated chips of these (A) to (C) under the conditions shown in Table 1 below.

Table 1 The test results are shown in Table 2.

Table 2 Example 2 A cemented carbide consisting of 95% by weight we and 5% by weight Co.
Regarding the saturation magnetic quantity 4πσ value/Co amount ratio = 158, at a temperature of 1000°C, (a) OH4 gas atmosphere, (b) Hz atmosphere, and (c) 100 torr, respectively.
Heat treatment was performed in an NH3 atmosphere.

Before the above treatment, the alloy had a VC
However, according to the process (a), up to 80 μm from the surface is WC! -CO phase 2
In the case of three-phase alloys in which more internal beam phases coexist in the phase region, and according to the steps (1) and (3), WC up to 60 μm
-Co was a two-phase region, and the interior beyond that was a three-phase region where η phase coexisted.

Example 3 Six chips subjected to the step (a) of Example 2 were subjected to TiC! using plasma CVD method. After coating amorphous BN with a thickness of 1 μm, hard I B
N 81 (? degree 3000 kg/wn”) f j-
When a cutting test was conducted under the same conditions as in Table 1, cutting was possible for up to 40 minutes. .

Among agents: 1) Akira Agent Ryo Hagi Hara -

Claims (1)

[Scope of Claims] (]) In a cemented carbide having wC as a hard phase and one or more iron group metals as a binder phase, mainly we A cemented carbide formed by precipitating double carbide consisting of
One or more selected from the group consisting of t, Si, and B, and O,
(2) Before coating the surface of the cemented carbide base material, a hydrocarbon, Under reduced pressure of 1 to 300 torr in a gas atmosphere of either Nz, NHs gas or CO,
The coated cemented carbide according to claim 1, wherein the coated cemented carbide is heated to a temperature of 900 to 1100°C to thereby eliminate one or more double carbides from the surface of the base material. (3) The saturation magnetic amount of the alloy containing Co as a binder phase is expressed as a ratio to the binder phase amount, and the scope of claim (1) or claim (2) falls within the following range:
Coated cemented carbide as described in section.