JPH02232106A - Polycrystalline diamond for tools - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention provides a tool for use as a cutting tool, a wear-resistant tool, etc., which has significantly improved strength, welding resistance, heat resistance, and wear resistance. Regarding polycrystalline diamond.

[Conventional technology]

As diamond for tools, diamond sintered bodies made by sintering fine diamond powder under ultra-high pressure are used in nonferrous metal cutting tools, drill bits, wire drawing dies, and the like.

For example, Japanese Patent Publication No. 52-12126 discloses that diamond powder is brought into contact with a powder compact or sintered body of We-Co based cemented carbide and sintered, and a portion of CO is contained in the diamond powder as a binder metal. By infiltrating approximately 1
A technique for manufacturing a diamond sintered body containing 0 to 15% by volume of CO is disclosed.

Although this diamond sintered body has practical performance as a cutting tool for non-ferrous metals, it has a drawback of poor heat resistance.

For example, if heated to 700C or higher, the wear resistance and strength will decrease, and if the temperature is 900σ or higher, the sintered body will break. This defect in heat resistance is thought to be due to graphitization of diamond occurring at the interface between diamond particles and CO, which is a binder, and thermal stress based on the difference in thermal expansion coefficients when the two are heated.

As an attempt to improve the heat resistance of the above-mentioned diamond sintered body, for example, Japanese Patent Application Laid-Open No. 114589/1989 proposes that the sintered body be treated with an acid to remove the bonding metal CO. However, this method has the disadvantage that the removed Co parts become pores, so even though the heat resistance is improved, the strength is reduced.

On the other hand, recently it has become possible to synthesize diamond using a chemical method of synthesis from the gas phase. As this chemical vapor phase synthesis method (CVN method), there are various proposals for exciting and decomposing raw material gases of hydrogen and hydrocarbons. For example, in Japanese Patent Application Laid-Open No. 58-91100, the above raw material gas is
Table of substrates heated after preheating with a thermionic emitter heated to 0 C' or higher? There is a method of depositing diamond by thermal decomposition of hydrocarbons;
- Publication No. 110494 describes a method in which diamond is precipitated in the same way by passing hydrogen gas through a microwave electrodeless discharge and then mixing it with hydrocarbon gas;
No. 9-30398 discloses that a microwave is introduced into a mixed gas of hydrogen gas and an inert gas to generate plasma, and a base material is placed in the plasma and heated to 300 to 1300 C'.
Methods of decomposing hydrocarbons and precipitating diamonds have been described. Also, JP-A-61-15889
No. 9 discloses mixing an oxygen-containing gas with a hydrocarbon as a raw material gas.

By applying these VD methods, tools in which polycrystalline diamond is coated on a base material are also provided. However, because the diamond film thickness is thin and the adhesion strength of the diamond to the base material is insufficient, sufficient performance as a tool cannot be obtained.

[Problem to be solved by the invention]

The present inventors investigated the shortcomings of such conventional diamond tools, and previously disclosed in Japanese Patent Application No. 63-34033 and No. 63-34034 a diamond tool formed on a base material by applying the CvD method. By separating crystalline diamond from the base material by chemical treatment or mechanical means and brazing it to a support member made of hardened steel or cemented carbide, it is possible to create a diamond tool with strength and wear resistance comparable to that of conventional diamond tools. proposed a diamond tool with far superior heat resistance.

However, as a result of evaluating the performance of diamond tools based on the above proposal, we discovered that there are differences in tool performance, particularly chipping resistance and wear resistance, depending on the type of polycrystalline diamond used as the tool material, leading to the present invention. It is something.

That is, an object of the present invention is to provide a polycrystalline diamond for tools with improved strength, adhesion resistance, heat resistance, and wear resistance, and particularly excellent fracture resistance and wear resistance.

(Means for Solving the Problems) In order to achieve the above object, the polycrystalline diamond for tools of the present invention has a thickness of 50 μm or more and an average crystal grain size of 50 μm or more.
μm or less, diamond carbon (diamond carbon) and non-diamond carbon (“i”) by Raman spectroscopy as an indicator of purity
') peak ratio (Y/X) is 0.2 or less, preferably O
, OS or lower.

In addition to the peak ratio of Raman spectroscopy, specific resistance, optical transmittance, dielectric loss, etc. can be used as an indicator of the purity of polycrystalline diamond, and in that case, the specific resistance is 10 Ω.
・The necessary conditions are that the visible light transmittance at a wavelength of 600 nm is at least 10%, and the dielectric loss at 100 KHz is at least 0.2. It cannot be said that there is a direct correspondence relationship.

[Effect]

It is a particularly important condition that polycrystalline diamond has high purity, and as an indicator of purity, one of the peak ratio of Raman spectroscopy, specific resistance, light transmittance, and dielectric loss is used as described above. In these purity indicators, the peak ratio (
When Y/X) exceeds 0.2, the specific resistance is 107Ω・c
m, if the visible light transmittance at wavelength 600 um is less than 10% range, or if the dielectric loss at ioOKHz is greater than 0.2, it contains a large amount of non-diamond carbon and other impurities. When used as a tool, such diamonds tend to have large defects, and wear due to micro-fractures and falling off of particles becomes noticeable. This is because non-diamond carbon exists between diamond particles, which reduces the bonding strength between the particles, and because there are many defects in the diamond particles precipitated under these conditions, the strength of the particles themselves is also low. It is presumed that this is due to the following reasons.

Polycrystalline diamond that satisfies these conditions has the above-mentioned C
It can be produced by selecting synthesis conditions based on the VD method, but in particular, plasma is used to excite the raw material gas, and oxygen-containing gases such as oxygen and water vapor are used in addition to hydrocarbons and hydrogen as the raw material gas. It is effective to do so.

In addition, it is preferable to select synthesis conditions so as to avoid mixing of impurities other than non-diamond carbon as much as possible.

In addition, the reason why the thickness of polycrystalline diamond is 50 μm or more is that when used as a cutting tool, the flank wear width during the life of the cutting tool is 50 μm or more.
This is because the thickness is often more than μm, and if it is thinner than 50 μm/Jm, the strength decreases and it becomes easy to break.

If more wear resistance is required, the thickness should be increased from 0.3 to 3.0.
It is preferable to set it to wK. This is because increasing the thickness improves heat dissipation characteristics and suppresses the rise in temperature at the cutting edge during tool use.Furthermore, the reason why the average grain size is 50 μm or less is to improve fracture resistance. The range of 1 μm to 10 μm is more preferable. This is because if it is larger than this range, fracture resistance gradually decreases, and if it is smaller than this range, wear resistance decreases. Such control of crystal grain size is disclosed in Japanese Patent Application No. 1983-139143 and Japanese Patent Application No. 1983 by the present inventors.
- It can be carried out by the method described in No. 148631 etc.

Incidentally, the polycrystalline diamond of the present invention synthesized by the CvD method or the like is separated from the base material and brazed to a support member, as in the above-mentioned Japanese Patent Applications No. 63-34033 and No. 63-34034. Use it as a tool, or if it is thick, use it as is/as a single tool.

〔Example〕

Example 1 H was used as a raw material gas by microwave plasma CVD method.
250 cc/minS (!H 5 cc/min
Using ns and Ar 80cc/min, pressure 200
Polycrystalline diamond was formed to a thickness of about 0.5811 mm on a Mo substrate in 20 hours using torr. The average crystal grain size of this polycrystalline diamond (A) on the growth top surface is approximately 40 μm.
Met. Next, under the same conditions as above except that 1.0% by volume of water vapor was further added to the raw material gas, approximately 0%
．． Polycrystalline diamond (B) was formed to a thickness of 4fi. The average crystal grain size was about 25 μm.

Thereafter, when the Mo base material was dissolved and removed by hot aqua regia treatment and the polycrystalline diamond was recovered, (A) was black and opaque, but (B) was white and transparent. In addition, the specific gravity was 3.52 in both cases, but the results of Raman spectroscopic analysis were as shown in Figure 1, and 1800 cm" 10 0
136 measured from background between 0 cm-'
Non-diamond carbon peak from 0 to 1580 cm (
The peak ratio (y/x) between peak 00 of diamond carbon measured with the periphery of the peak at 1333 cm-' as the background is 0.32 for (A), while 0.32 for (B). It was 05. Also, the specific resistance is (A) 3
(B) 7 X 1.0 for X 10 Ωmcm
Ω@cm, visible light transmittance at wavelength 600 nm (sample thickness 50 μm) is (A) 3% and (B) 60%,
and the dielectric loss at 100 KHz is (A) 0. 95
(B) was 0.03, and it was clearly found that (B) had a lower content of non-diamond carbon and had higher purity.

Next, in order to evaluate tool performance, each polycrystalline diamond was brazed to a cemented carbide alloy to create a cutting tip. As a comparison material, a cutting tip was produced in the same manner using ultra-high pressure sintered diamond containing 10% by volume of Co as a binder and having an average grain size of 10 μm.

Nine bars of A390 alloy (Al-17SL) with four grooves extending in the axial direction on the outer circumferential surface were used as the work material, cutting speed was 300 m/min, depth of cut was 0.2 sieve, and feed rate was 0.
．． 11111/rev. The tool performance was evaluated by dry cutting under the following conditions.

As a result, (A) was damaged after 40 minutes of cutting, but (B)
) is not chipped, and the average wear width after 90 minutes of cutting is 0.04.
It was a crane. Although the comparative material did not suffer from any chipping, the average wear width after 90 minutes of cutting was 0.0'lllfi.

Example 2 Using a linear tungsten filament with a diameter of 0.5 mm and a length of 20 mm as the thermionic emitting material, a raw material gas consisting of hydrogen, a carbon source, and water vapor was decomposed and excited, and the materials shown in Table 1 were deposited on an 81 base material. Polycrystalline diamond was formed under the conditions shown for 10 hours.

Table 1 When each of the obtained polycrystalline diamonds (0) to (H) was acid-treated and separated and recovered from the 81 base material, (D) and (E) were obtained.
was black and opaque, but all the others were white and translucent. Table 2 shows the results of measuring the film thickness, average crystal grain size, and purity index of each polycrystalline diamond.

Table 2 (Note) Measurements of peak ratio (X/Y), transmittance, and dielectric loss were the same as in Example 1.

A cutting tip was prepared by brazing each polycrystalline diamond (C) to (H) to a cemented carbide alloy, and an AC8A alloy (Aj-12
Si) Round bar as work material, cutting speed 500m/m i
n s incision 0.2, feed O, l s*/rsy
Table 3 shows the results of dry cutting for 90 minutes under the following conditions.

Table 3 Samples (0), (F), and (G) according to the present invention all showed good tool properties, but sample (D> had low purity but relatively fine particles, so no fracture occurred. of things,
Since the purity was low, the abrasion resistance was poor; sample (E) had a coarse grain size and low purity, and sample 6) had a thin thickness and reduced strength, so they broke off in a short time.

Example 3 Adding 0 to the mixed gas of CH:H (volume ratio 1:100)
Using a raw material gas containing 0 to 20% by volume of S1 in reaction time
Polycrystalline diamond with a thickness of 0.5 to 0.7 m was formed on the base material.

Among the obtained polycrystalline diamonds, the average grain size was 7 μm.
and 650 .mu.m in thickness, different purity was selected based on each purity index, and each was brazed to a cemented carbide holder and subjected to a cutting treatment to evaluate the cutting performance of hard ceramics. Cutting evaluation was performed using alumina sintered round bar (Ih
r-2000◆1) outer circumferential turning at a cutting speed of 50 rn
/min 1 cut 0.2fi, feed 0. 25M
yrev. The test was carried out in a wet manner for 15 minutes under the following conditions. The relationship between the purity index and flank wear width was determined and shown in FIGS. 2 to 5, respectively.

From this result, it can be seen that those having any purity index within the range of the present invention have excellent wear resistance.

〔Effect of the invention〕

According to the present invention, it is possible to provide a polycrystalline diamond for tools with improved strength, welding resistance, heat resistance, and wear resistance, and particularly excellent fracture resistance and wear resistance.

Therefore, high-performance tools can be manufactured using this polycrystalline diamond, and are particularly effective for tools such as cutting tools, excavation tools, and dressers.

[Brief explanation of the drawing]

Figure 1 is a graph showing the results of Raman spectroscopic analysis of the polycrystalline diamond produced in Example 3, and Figures 2 to 5 are the width of flank wear of the polycrystalline diamond produced in Example 3 and Raman spectroscopy as a purity indicator. 3 is a graph showing the relationship among spectroscopic analysis peak ratio, specific resistance, visible light transmittance, and dielectric loss. Applicant: Sumitomo Electric Industries, Ltd. Figure 1 Figure 2 Raman spectroscopy peak ratio (Y/x)

Claims (4)

[Claims] (1) The thickness is 50 μm or more, the average crystal grain size is 50 μm or less, and the peak ratio (Y/X) of diamond carbon (X) to non-diamond carbon (Y) is 0 as determined by Raman spectroscopy as an indicator of purity. A polycrystalline diamond for use in tools, characterized in that it has a particle diameter of .2 or less. (2) A polycrystalline diamond for tools, which has a thickness of 50 μm or more, an average crystal grain size of 50 μm or less, and a resistivity of 10 Ω·cm or more. (3) The thickness is 50 μm or more, the average crystal grain size is 50 μm or less, and the visible light transmittance at a wavelength of 600 nm is 10%.
A polycrystalline diamond for tools characterized by the above. (4) A polycrystalline diamond for tools, which has a thickness of 50 μm or more, an average crystal grain size of 50 μm or less, and a dielectric loss of 0.2 or less at 100 KHz.