JPH0578845A - Sintered alloy coated with high-adhesion diamond - Google Patents

Abstract

PURPOSE:To improve the adhesion between a sintered body and a diamond layer by incorporating a specified intermetallic compound into the bonding phase of the sintered alloy at the time of coating the surface of a sintered alloy obtd. by sintering hard metallic carbide with Ni or Co as a bonding phase. CONSTITUTION:A superhard diamond coating layer is formed on the surface of a wear resistant tool made of a hard sintered alloy essentially consisting of, by volume, 80 to 99% hard intermetallic compound of the carbide or nitride of the group TVa, Va or VIa metals in a periodic table or their mutual solid soln., particularly WC or the like and the balance Ni, Co or the like with Fe- group metal as a bonding phase to improve its wear resistance and to prolong its service life. At this time, an intermetallic compound consisting of Ni, Co, Al and Si is incorporated by >=50vol.% into sintering bonding material consisting of Ni or Co. The peeling resistance of the diamong coating layer against the hard sintered alloy improves, and the service life of the wear resistant tool can be prolonged.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a highly adherent diamond-coated sintered alloy suitable for use as a cutting tool for turning tools, milling tools, drills, end mills, etc., or as a wear resistant tool for slitters, wire cutters, guides and the like. The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art Attempts have been made to apply a diamond-coated sintered alloy in which a coating film of diamond and / or diamond-like carbon is formed on the surface of a base material of a sintered alloy represented by cemented carbide to a cutting tool.

When the diamond-coated sintered alloy is used as a cutting tool, the greatest problem is the adhesion between the base material and the coating.

Attention has been paid to the adhesiveness between the base material of the sintered alloy and the diamond coating, and many proposals have been made as a diamond-coated sintered alloy suitable for a cutting tool. There are 126972 and JP-A-63-53269.

[0005]

Problems to be Solved by the Invention JP-A-58-1269
No. 72 discloses that the inner layer adjacent to the cemented carbide base material has a periodic structure.
Carbides, nitrides and phosphors of metals of groups 4a, 5a and 6a
Bromides, oxides and their compounds, mixtures and Al
₂O₃, AlN, B_FourC , Si₃N_Four, SiO₂, From SiC
Consists of one or more selected materials, with an outer layer of diamond
A diamond-coated cemented carbide is disclosed. concrete
The invention of the publication is based on a cemented carbide base material containing Ni or Co.
When the diamond coating is applied directly to the material, graphite
Easily precipitates, and the decrease in adhesion between the substrate and the coating becomes remarkable.
The chemical vapor deposition method between the substrate and the coating
WC by (CVD method) or physical vapor deposition method (PVD method)
And W₂C Try to solve by interposing the inner layer of
It is a thing.

However, the adhesion between the inner layer and the diamond coating disclosed in the above publication has not reached such a level that it can be put to practical use as a cutting tool, and it is necessary to additionally provide an inner layer forming step in the manufacturing process. There is a problem in quality control that the process is complicated and the control of the amount of carbon during the process of forming the inner layer affects the material of the diamond coating and the adhesion between the base material and the coating.

Japanese Patent Laid-Open No. 63-53269 discloses that
Disclosed is a diamond-coated cemented carbide formed by etching the surface of a cemented carbide containing 4 wt% of Co and the balance tungsten carbide, and forming a diamond coating with an etching layer interposed on the surface of the cemented carbide. There is.

The invention of the above publication discloses that Co on the surface portion of the cemented carbide.
Is removed with an acid solution to form an etching layer, and a diamond film is formed on the surface of the etching layer.
In the void portion after the removal of o, Co inside the cemented carbide exudes and is filled in during the formation of the diamond coating film again, which facilitates the local grain growth of diamond, and the diamond coating film and the etching layer. There is a problem that the adhesion between the coating and the cemented carbide is low because graphite is likely to be generated at the interface.

The present invention has solved the above-mentioned problems. Specifically, a substrate containing an intermetallic compound suppresses graphite generation during the formation of a diamond film, and provides a high quality diamond film. It is an object of the present invention to provide a diamond-coated sintered alloy capable of forming an alloy and improving the adhesion between the base material and the diamond coating.

[0010]

[Means for Solving the Problems] When forming a diamond film on the surface of a cemented carbide base material, the present inventors have proposed a method for suppressing the precipitation of graphite on the surface of the base material and the adhesion between the base material and the coating. Where I was thinking about improving
The iron group metal contained in the base material as a bonding layer has the function of precipitating graphite during the formation of the diamond film, whereas the bonding phase containing the intermetallic compound, especially the iron group metal in the bonding phase It has been found that in the case of a binder phase containing an intermetallic compound, the precipitation of graphite is suppressed during the formation of a diamond film, and the adhesion between the base material and the diamond film is significantly improved.

The present invention has been completed based on the above findings.

The highly adherent diamond-coated sintered alloy of the present invention is a carbide of a group 4a, 5a or 6a metal of the periodic table,
Diamond and / or diamond on the substrate surface of a sintered alloy consisting of 80 to 99% by volume of one or more hard phases in a nitride and their mutual solid solution, and the remainder being a binder phase containing Co and / or Ni as a main component. Alternatively, it is a diamond-coated sintered alloy formed by forming a coating of diamond-like carbon, characterized in that the binder phase contains an intermetallic compound.

Specifically, when the hard phase constituting the base material in the coated sintered alloy of the present invention is composed of, for example, only WC, WC is the main component and TiC, ZrC, and Hf are included.
C, TaC, NbC, VC, Mo ₂ C, Cr ₃ C ₂ ,
(W, Ti) C, (W, Ta) C, (W, Ta, Ti)
C, (W, Ta, Nb, Ti) C, TiN, Ti (N,
C) and their mutual solid solutions, Ti
C or Ti (C, N) as the main component, WC, Zr
C, HfC, TaC, NbC, VC, Mo ₂ C, Cr ₃ C
₂ , TiN, ZrN and their mutual solid solutions may be included. When this hard phase is less than 80% by volume with respect to the entire substrate, the binder phase becomes 20
The content of the hard phase is significantly higher than the volume%. As a result, the hardness of the base material is remarkably reduced, and the wear resistance of the base material at the time when the coating is lost is extremely deteriorated. If the amount exceeds more than 0.1%, the binder phase becomes relatively less than 1% by volume, and as a result, the strength of the base material is remarkably reduced, the base material is apt to be damaged, and it becomes difficult to sufficiently exert the effect of the coating film.

The binder phase constituting the base material in the coated sintered alloy of the present invention is one in which an intermetallic compound is contained in the main component Co and / or Ni. Specifically, for example, Co And / or Ni and an intermetallic compound, Co and / or Ni are the main components, and Ti, Z
In the case of being composed of r, Hf, W, Mo, Cr, Fe and an intermetallic compound, the intermetallic compound is NiS.
i ₂ , CoSi ₂ , TiSi ₂ , MoSi ₂ , WSi ₂ , F
e ₃ Al, NiAl, Ni ₃ Al, Ni ₃ Nb, CoA
l, Co ₂ Al ₅ , Co ₃ Ti, Zr ₃ Al, Ni ₃ (A
1, W), Ni ₃ Si, Ni ₂ (Al, Ti), TiA
1, TiAl ₃ , Nb ₃ Al, V ₃ Si may be mentioned. This intermetallic compound contains Co and / or Ni and A
1 and / or Si, for example NiSi ₂ , CoS
i ₂ , NiAl, Ni ₃ Al, CoAl, Co ₂ Al ₅ , N
i ₃ (Al, W), Ni ₃ Si, Ni ₂ (Al, Ti),
Is particularly preferable because it has a high effect of accelerating the formation of the film, and the intermetallic compound is 50% or more by volume ratio with respect to the binder phase. It is preferably contained, and more preferably 80% or more from the viewpoint of the peeling resistance of the coating and the effect of promoting the formation of the coating.

The coating constituting the coated sintered alloy of the present invention is a diamond film having a peak at about 1333 cm ^-1 showing the crystal structure of diamond in Raman spectroscopic analysis, or this diamond and other amorphous carbon. In some cases, it may contain glassy carbon, glassy carbon, or the like, or may be composed of diamond-like carbon that is said to exhibit properties close to diamond. The thickness of this coating needs to be selected according to the application and shape, and particularly for applications where importance is attached to scrape abrasion resistance rather than impact resistance, for example, 3 to 1
A thickness of 0 μm is preferable, and a cutting tool has a thickness of 0.5 to 7 μm.
Thickness is preferable, and among cutting tools, such as cutting tools for milling, where impact resistance is important, or sharp cutting angles such as cutting tools such as drills and end mills, and abrasion resistant tools such as slitters, cutting blades and cutting blades. It is preferable that the shape having a sharp cutting edge has a thickness of, for example, 0.5 to 3 μm and a thin coating.

In order to produce the coated sintered alloy of the present invention, a base material is produced by applying a conventional powder metallurgy method, and then a pretreatment such as a scratch treatment or a cleaning treatment on the surface of the base material is performed. Then, a diamond coating treatment by vapor phase synthesis which has been conventionally performed can be performed.

[0017]

In the highly adherent diamond-coated sintered alloy of the present invention, the intermetallic compound contained in the binder phase constituting the base material has the function of suppressing the generation of graphite in the initial stage of film formation. , Promotes the formation of a film, enhances the strength and hardness of the base material at high temperature, and enhances the adhesion between the coating and the base material after the formation of the film. It is a thing.

[0018]

Example 1 Commercially available WC having an average particle size of 1.5 μm
Powder, W and Ni powder with an average particle size of 1.0 μm, average particle size
The composition shown in Table 1 was compounded using 0.2 μm Al powder.
It was Then, in a ball mill of acetone solvent at 24:00
In the meanwhile, the mixed powders are mixed and pulverized, and dried and paraffin of 1% by weight is mixed.
1 after adding tin t / cm²Molding with pressure
A powder compact was obtained. 5-8 × 10 of these powder compacts
^-2Sintered at 1650 ° C for 1 hour in a Torr vacuum
And the sintered alloys used in the present invention products 1 to 4 and comparative products 3 and 4.
A base material of

The base material of the sintered alloy used for Comparative Products 1 and 2 is
It was obtained in the same manner as above except that it was sintered at 1450 ° C.

The intermetallic compounds in these base materials were confirmed by X-ray diffraction, SEM and XMA, and the results are also shown in Table 2.

The surface of these substrates was polished and washed.
Then, by microwave plasma CVD method, 9 vol
% -1 vol% CH_FourGas atmosphere, 200 SCCM gas
Flow rate, 50 Torr pressure, hold for 4 hours, 930-950
Depending on the condition of the substrate temperature of ℃,
An earmond coating was formed.

Observation of the state of the coating film of the coated sintered alloy thus obtained revealed that the comparative products 1 and 2 had already partially or entirely peeled off the film when taken out from the film forming reactor. On the other hand, the films of the present invention products 1 to 4 and the comparative products 3 and 4 were not peeled off. Next, the present invention products 1 to 4
And the peeling test of the coating of the comparative products 3 and 4 by the Rockwell indenter press-fitting method, the products of the present invention 1 to 4
Was not peeled off near the indentation,
In Comparative Products 3 and 4, peeling of the coating occurred near the indentation.

[0023]

[Table 1]

[0024]

Example 2 Using the WC and Al powders used in Example 1 and the Co powder having an average particle size of 3.0 μm, the composition shown in Table 2 was compounded, and otherwise the same as in Example 1 to carry out the present invention. Item 5
I got 14.

A film peeling test by a Rockwell indenter press-fitting method with a load of 30 kg was carried out on the surface of the films of the products 5 to 14 of the invention thus obtained. Is obtained from the metallurgical micrograph, and the ratio of the average film peeling deformation area and the average indentation area It was calculated as, and it was written together in Table 2.

[0026]

[Table 2]

[0027]

EFFECTS OF THE INVENTION The high adhesion diamond-coated sintered alloy of the present invention is more likely to form a high-quality diamond coating than the conventional diamond-coated sintered alloy or the diamond-coated sintered alloy deviating from the present invention. , And the adhesion between the coating and the substrate is enhanced, and the peeling resistance of the coating is significantly improved.

Claims (3)

[Claims] 1. 80 to 99% by volume of one or more hard phases in carbides and nitrides of metals of groups 4a, 5a and 6a of the periodic table and mutual solid solutions thereof, and the balance of Co and / or N.
In a diamond-coated sintered alloy having a coating of diamond and / or diamond-like carbon formed on the surface of a base material of a sintered alloy having a binder phase containing i as a main component, the binder phase contains an intermetallic compound. A high-adhesion diamond-coated sintered alloy characterized by being 2. The intermetallic compound is Co and / or Ni.
And a high adhesion diamond-coated sintered alloy according to claim 1, characterized in that the intermetallic compound with respect to the binder phase is contained in a volume ratio of 50% or more. .. 3. The highly adherent diamond-coated sintered alloy according to claim 1, wherein the hard phase is composed mainly of tungsten carbide.