JPH0320467A - Diamond-coated sintered compact excellent in adhesion and its production - Google Patents

Abstract

PURPOSE:To produce a diamond-coated sintered compact excellent in adhesion by decarburizing the surface layer of a base material of sintered compact consisting of a hard phase composed principally of WC and then forming a diamond film on the surface layer by a vapor phase synthesis method and also forming the surface layer into a layer composed principally of WC. CONSTITUTION:A base material of sintered compact consisting of a hard phase composed principally of WC (containing >=90vol.% WC) and inevitable impurities (<= about 0.5vol.% of Co, Ni, Fe, etc.) is disposed in a reaction vessel, and the atmosphere in the reaction vessel is regulated to decarburizing atmosphere and subjected to temp.- rise to decarburize the surface layer of the base material. At this time, the grain size of WC in the surface layer from the base-material surface to the depth of 10mu is regulated so that it is finer than the mean grain size of WC in the inner part. Subsequently, the film of diamond and/or diamond-like carbon is formed on the surface layer of the base material to 0.5-10mu thickness by a vapor phase synthesis method, and simultaneously, the surface layer is formed into a layer composed principally of WC. By this method, the diamond-coated sintered compact excellent in adhesion can be obtained. This sintered compact is useful for cutting tool material.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an adhesive bond formed by forming a film of diamond and/or diamond-like carbon on the surface of a base material of a ceramic sintered body mainly composed of tungsten carbide. Regarding a diamond-coated sintered body with excellent properties and its manufacturing method,
Specifically, for example, cutting materials. Electrical products such as wear-resistant tool materials or decorative materials! ．． ? 11th child industry. I
I1 Secret equipment industry. The present invention relates to a diamond-coated sintered body with excellent neck-tightness suitable as a material for parts used in the office equipment industry, etc., and a method for manufacturing the same.

(Conventional technology) Traditionally metal. A diamond is made by forming a diamond and/or a diamond-like coating on the surface of a material made of a sintered body such as an alloy or ceramic. Since diamond has poor wettability with other substances, this diamond-coated la sintered body is made by applying a coating of diamond and/or diamond-like carbon to the surface of the base material to improve adhesion and adhesion. The question of whether it is possible to cover the situation has become a major issue for most people. In particular, turning T only. Milling cutter - [Ingredients. Drill. In the case of materials for cutting tools such as end mills, adhesion and rejuvenation between the coating and the material are important issues since they are used under the most severe conditions.

Many diamond-coated sintered bodies have been proposed that can be used as cutting tool materials by increasing the density of the diamond coating and the JJ material. Publication No. 62-57802, JP-A-62
-166904 and Japanese Unexamined Patent Publication No. 6399102.

(Problems to be Solved by the Invention) Japanese Patent Application Laid-open No. 62-57802 discloses a method of depositing a hard carbon thin film on a base material surface using a vapor phase to cover a hard carbon coated part with the hard carbon thin film and the base material. The middle h1 of the compound thin film of W and C containing WIC as the main component is set to have a thickness of O. l
A hard carbon coated part is disclosed that has a carbon coating of more than gm ft. The invention according to the same publication is based on the use of CvD (chemical vapor deposition) or PV on the surface of a base material made of cemented carbide or ceramics.
W and C with LC as soil component using D method (physical vapor deposition method)
It is said that when the intermediate layer is coated with a thin compound film, a diffusion intermediate layer of WC is formed at the interface between hard carbon and C, and as a result, an improvement in adhesion strength can be achieved.
This is because the process of forming an intermediate layer using the CvD method or PVD method and then coating it with a hard carbon thin film in a separate reaction vessel is complicated, and the surface of the intermediate layer is likely to be contaminated with impurities and turn blue. There is a problem in that the adhesion between the intermediate layer and the hard carbon thin film is poor.

JP-A-62-166'104 discloses silicon nitride, silicon carbide, zirconium oxide. The base material is a ceramic sintered body whose main component is aluminum oxide, and a 11 l. A ceramic sintered body formed by coating a thin film of hard carbon with a thickness of 0.5 to 50 μm at the bottom of the cutting T. It is disclosed. The invention of this publication is
By using ceramics with high deformation resistance as JJ material and forming a thin film of hard carbon on its surface, it has become possible to cut fine ceramics, which are difficult-to-cut materials. The more diamonds are contained in the material, the more dense the material and the thin film are.
There is a problem in that the wear resistance deteriorates as the E content of diamond decreases.

JP-A No. 63-99102 discloses that tungsden is used as a base material, and diamond is coated with a thickness of 1 to 100 μm on the material.
A covered tungsten ball l1 is disclosed. The invention in the same publication is based on the J of cemented carbide and ceramics.
The conventional diamond coated tool with a diamond thin film formed on the surface of the material is F! Although there was a problem with the coupling strength between the J film and the base material, the issue of coupling strength was solved by using tungsten as a JA material.
Since the tungsten RL body is soft, it is easily deformed and can be cut. Even if it is used as 1, it has a short lifespan.

The present invention solves the above-mentioned problems. Specifically, the present invention has excellent scratch releasability between the base material and the diamond and/or diamond-like carbon coating, and can be used as a material for cutting tools. The object of the present invention is to provide a diamond-coated sintered body and a method for manufacturing the same.

(Means for Solving the Problems) The present inventors have determined that when coating fin material with a diamond film formed by vapor phase synthesis, the type of material used. 17 Testing the peeling resistance between the coating and the J, l, material under the thickness of the coating and the coating formation conditions 3-1, a diamond coating was formed on the surface of the base material of the sintered body made of tungsten carbide. In this case, unlike cemented carbide or cermet base materials containing Fe group metals, the precipitation of graphite at the initial stage of diamond vapor phase synthesis is suppressed, and We discovered that if decarburization treatment is performed before forming a diamond film, and then a diamond film is formed, the adhesion between the tungsten carbide base material and the first pattern becomes even stronger, allowing it to be put to practical use as a cutting material. That's what I got. Based on this finding C, we have completed the present invention.

That is, the diamond-coated sintered body with excellent adhesion of the present invention has a coating of diamond and/or diamond-like carbon on the surface of the JS material, which is a sintered body consisting of a hard phase mainly composed of tungsten carbide and unavoidable impurities. It is characterized by the formation of

The hard phase in the diamond-coated sintered body of the present invention is composed of only tungsten carbide, or tungsten carbide contains at least 5 ovojl% in the hard phase,
Also periodic table 4a. Carbide of Sa, group 6a metal. This is the case when it contains at least one kind of carbide and a phase mound solid solution thereof. Of these, especially the hard phase is 9
0voj! % or more of tungsten carbide, for example wC or wc-w. When consisting only of tungsten carbide consisting of c, or these tungsten carbide 9σ
VI consisting of wail% or more-L and remaining molybdenum carbide
C MotC. WC WaC MnxC or IC - (V4, Mo)C, what about the coating and JJ material? ? ? ? ? This is preferable because it has excellent properties and the strength of the base material.

The base material of the diamond-coated sintered body of the present invention contains unavoidable impurities in addition to the above-mentioned hard phase, and these unavoidable impurities mainly include impurities contained in the starting material and mixtures of the starting material. There are impurities that get mixed into the crushed T culm, and the latter impurities include Coy Ni that gets mixed in from the mixing container or ball, etc.
．． Fe. II, Cr. MO, etc., and even if these unavoidable impurities are contained in the base material at 0.5 vol2% or less, there is little decrease in the adhesion between the base material and the coating, and it is said that it actually supplements the strength of the J construction material. It is possible because it is effective. These base materials exist in the surface layer of at most 10 μm from the surface of this material toward the inside.
The particle size of tungsten carbide in F is
In addition, if we move to the surface of the material, which is finer than that of the tungden carbide shell, which has t7-/E inside the material, J, I
This is particularly preferable because it improves the adhesion between the material and the coating and improves the quality of the coating.

↑,! , the diameter of the tungsten carbide in the surface liquor is 1.0.
Less than μm. Preferably, when the thickness is 0.5 μm or less, the adhesion between the base material and the coating becomes even better.

What is the coating in the diamond-coated sintered body of the present invention? l
Qi resistance. Light transmittance. Hardness etc. are properties of diamond or properties similar to diamond, and 11 physical properties are:
When subjected to Raman spectroscopy, it shows a peak at 1333 cm-', which is said to be the Raman line of diamond. Furthermore, if this coating consists only of diamond, or if it contains non-quality carbon or glassy carbon in addition to diamond, or even if it does not contain diamond, it may be It is often made of diamond-like carbon, which is said to have similar properties. Especially 0?
In the case of a film formed on a base material with surface collapse as described in i above, the peak of 1333 cm-', which is said to be the Raman line of diamond in Raman analysis, clearly appeared. Become something. The thickness of this coating is
It varies depending on the use and shape, and in particular, for uses where bamboo is more resistant to scraping than impact resistance, it is preferably 3 to 10 μml, and for use as a cutting tool material, it is preferably 8. A thickness of .5 to 7 μm is preferred, and among cutting tool materials, applications where impact resistance is important such as cutting tools for milling, drills and end mills, and wear-resistant tool materials such as slitters and cutting blades. For applications with sharp cutting edges such as cutting blades, for example, 0.5 to 3μ
It is preferable to adopt a structure in which the thickness is m and the coating is thin.

In the diamond-coated sintered body of the present invention, a starting material for forming a hard phase mainly composed of tungsten carbide is made into a sintered body by a conventional powder metallurgy method, and the surface of the base material of this sintered body is coated. Conventional microwave plasma. Although it can be obtained by forming a diamond film by vapor phase synthesis in high-frequency plasma or hot filament plasma, the following method is preferable because the adhesion between the base material and the film is better. be. That is, in the method of manufacturing a diamond-coated sintered body with excellent adhesion according to the present invention, a sintered body base material consisting of a hard phase mainly composed of tungsten carbide and unavoidable impurities is placed in a reaction vessel, 9i. with a decarburizing atmosphere inside the reaction vessel. After decarburizing the surface layer of the cultivated material by heating, 1. forming a coating of diamond and/or diamond-like carbon on the surface layer of the cultivated material using a vapor phase synthesis method, and exposing the surface layer to the market. This method is characterized by turning carbide into scraps whose main component is tungsten carbide.

The base material in the manufacturing method of the diamond-coated sintered body of the present invention is prepared by mixing and pulverizing a starting material mainly composed of tungsten carbide, followed by hot press sintering or delta sintering, followed by hot isostatic pressing Fl. ! (IIIP treatment) allows a dense sintered body to be obtained.

The base material obtained in this way was placed in a reaction vessel for diamond vapor phase synthesis, and heated in a decarburizing atmosphere in the reaction vessel to a depth of at most 10 μm from the surface of the convex material to the inside. After decarburizing the layer, a diamond coating treatment is performed using the vapor phase synthesis method, and the surface layer that has been overnight carbonized is turned into a regenerated tungsten carbide or a carbide whose main component is tungsten carbide. This is a method of forming a coating of diamond and/or diamond-like carbon on layer-L.

After decarburizing the surface layer of the base material in this way, the recrystallized tungsten carbide that is formed again as a carbide can have a finer grain size than the tungsten carbide inside the base layer than the surface layer. In the method for producing a diamond-coated sintered body of the present invention, creating a decarburizing atmosphere inside the reaction vessel can be done by using a divine gas atmosphere. For example, hydrogen gas and I
It is preferable that the atmosphere consists of a mixed gas with lv2 elementary gas, or a mixed gas of hydrogen gas, oxygen gas, and a gas that can be a source of carbon. It is necessary to be careful as agitation may occur depending on the proportion, especially oxygen gas 0.1 to 5%.
In the case of a decarburizing atmosphere with a ratio of This is a good thing because it is The gas that can be a source of carbon here is, for example, methane. Ethane. propane. butane. methanol. Ethanol, probanol, butanol. Examples include organic compounds containing carbon and hydrogen or carbon, hydrogen, and oxygen, such as methyl ether and ethyl ether. This decarburization property': When increasing the temperature by 3ν, the temperature of the base material is set to 500 to 1200.
It is a good idea to perform plasma conversion treatment at ℃.

Plasma treatment at this time can be performed using conventional microwave, high frequency, or hot filament methods, and in this plasma treatment state, diamond coating treatment using the conventional vapor phase synthesis method is subsequently performed in the same reaction vessel. This is strange because there is almost no impurity buildup between the surface and the coating.

(Function) The diamond sintered body with excellent adhesion of the present invention has the following properties:
The tungsten carbide in the J^ material has the effect of increasing the adhesion with the coating.In particular, the recycled fine tungsten carbide formed on the surface of the base material improves the adhesion with the coating. It has the effect of improving the film quality and increasing the abrasion resistance and removability of the film.

5 of the diamond-coated sintered body with excellent adhesion of the present invention
In the J manufacturing method, a surface layer made of fine grained recycled carbide, especially tungsten carbide, is formed through a treatment process in a decarburizing atmosphere and an initial step in the diamond coating process using the vapor phase amalgamation process. Moreover, the decarburizing atmosphere during plasma treatment and the diamond coating treatment during plasma treatment can be performed continuously in the same reaction vessel.
As a result, impurities are deposited at the interface between the surface ribs and the coating. Moreover, it makes it difficult to promote diamond nucleation and makes it easier to form a film consisting of fine grains.

(Example) Example 1 WC and MoxC with an average particle size of 3.0 μm were mixed and ground in a wet ball mill with cemented carbide balls, and after drying,
Hot press sintering was carried out in a vacuum to obtain a sintered material containing WC as a main component. After the surface condition of this base material is burnt or ground as shown in Table 1, it is decarburized under the decarburizing atmosphere conditions described in IA) below, and then lowered in the same reaction vessel. ．． SL! ! Product 1.2.4 of the present invention was obtained by forming a diamond coating on the surface of J, r+ material under the diamond coating treatment conditions of II). It was. Also, what about the decarburization treatment under the following conditions (A)? Inventive product 3 was obtained by forming a diamond coating 1yL on the surface of No. 1 (mura) under the conditions described in (b).

(A) Decarburizing atmospheric conditions Gas composition 99vol%llx - 1 von
%0, Gas pressure 60 Torr True material temperature 930℃ Microwave output 0.7 kW Treatment time 30 min tB) Diamond coating treatment conditions Gas composition 911voI2%Il2-2vnl2
．． %CIL gas pressure 80 Torr Base material temperature 1060 ℃ Microwave output 1.0 km Processing time ! 20 rain As a comparative product, Comparative Product 1 was obtained by subjecting the surface of a commercially available silicon nitride ceramic base material to the above treatment ([1)].

In addition, a commercially available cemented carbide material was placed in a separate reaction vessel.
L, . w+-a-CI1. - I1. Approximately W2C is applied to the surface of the planting material by CVD treatment in a mixed atmosphere.
After 1.5 μm of overlapping, the comparative product 2 was prepared by applying the treatment described in [11].Furthermore, the commercially available W plate was made into J, I+ material, and this bracket was subjected to the treatment described in (B) above. Comparative product 3 was obtained.

In this way, the present invention product 1.2.3.4 and comparative product 1,
The thickness of the diamond coating of No. 2.3 was investigated and shown in Table 1. In addition, the surface cracks of the Al-treated sample of product 1.2.4 of the present invention were examined using X-ray diffraction and SEM.
The results are also listed in Table I.

These invention products 1.2.3.4 and comparative products 1.2.3
Using the following condition (C). (b) A cutting test was conducted under various conditions, and the uniform flank wear and scratch conditions were observed. The results are shown in Table 2.

tc) Turning test conditions Workpiece material Chip shape Cutting speed Feed Cutting time evaluation {0} Turning test conditions Workpiece material Chip shape Cutting speed Feed Cutting depth Kai Cutting time ﾆ Flood l 8% Si alloy SI'GN 120308 226 m/min 0.1 mm/rev O, 5 mrn 20 min Average flank wear FiNV1, mm) Hard carbon SNCN 43ZFN 356 m/min O. 06 mm/rev 0.5 mm 60 min Below margin (Effects of the invention) From the above results, the diamond-coated sintered body with excellent adhesion of the present invention is a silicon nitride ceramic base material.W
．． Compared to the conventional diamond-coated sintered viscous material in which a diamond coating is formed on each surface of a cemented carbide metal-containing base material of H or W containing coated scraps of C, the density between the coating and the base material is lower. nW is excellent, and when used as a cutting engineer material, the peeling resistance of the coating is very good, resulting in excellent wear resistance and chipping resistance.
It has the effect of improving your life by 20% to 8 times.

In addition, the method of manufacturing a diamond-coated sintered body with excellent tightness according to the present invention allows the surface of the base material to be formed into a surface layer of fine grains mainly composed of tungsten carbide, and this surface layer and the coating can be It has the effect of making the adhesion of the powder even better.

Claims (6)

[Claims] (1) Excellent adhesion characterized by forming a diamond and/or diamond-like carbon film on the surface of a sintered body base material consisting of a hard phase mainly composed of tungsten carbide and unavoidable impurities. Diamond-coated sintered body. (2) The diamond-coated sintered body with excellent adhesion according to claim 1, wherein the hard phase is made of 90 vol% or more of tungsten carbide. (3) The base material has a grain size of tungsten carbide in the surface layer of at most 10 μm from the surface of the base material inward, compared to the average grain size of tungsten carbide present in the interior excluding the surface layer. A diamond-coated sintered body with excellent adhesion according to claim 1 or 2, characterized in that the diamond-coated sintered body has a fine grain. (4) A diamond-coated sintered body with excellent adhesion according to claim 1, 2, or 3, wherein the coating has a thickness of 8.5 to 10 μm. (5) A sintered body base material consisting of a hard phase mainly composed of tungsten carbide and unavoidable impurities is placed in a reaction vessel,
After decarburizing the surface layer of the base material by raising the temperature in a decarburizing atmosphere in the reaction vessel, diamond and/or diamond-like carbon is added to the surface layer of the base material by vapor phase synthesis. A method for producing a diamond-coated sintered body with excellent adhesion, characterized by forming a film and making the surface layer a layer containing tungsten carbide as a main component. (6) The decarburizing atmosphere is comprised of a mixed gas of hydrogen gas and oxygen gas, or a mixed gas of hydrogen gas, oxygen gas, and a gas that can be a source of carbon. 4. A method for producing a diamond-coated sintered body with excellent adhesion according to item 4.