JPS58199777A - Diamond sintered body for tool and manufacture - 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] Currently, for cutting non-ferrous metals, plastics, and ceramics,
Sintered bodies with a diamond content exceeding 7096 by volume are commercially available for use in wire drawing dies, dressers, and drill bits. Since these diamond sintered bodies are polycrystalline, they do not suffer from defects due to cleavage unlike natural diamonds, and are popular in some applications.

However, diamond sintered bodies have the following drawbacks. Generally, the larger the diamond grain size of a diamond sintered body, the better its wear resistance, so a sintered body with a larger diamond grain size is used for machining hard materials such as ceramic cutting machines, dressers, and drill bits. on the other hand,
Cutting non-ferrous metals often requires good surface roughness, and sintered bodies with fine diamond grains are used because they must have good edge sharpness. When cutting metals that contain a large amount of hard particles, the cutting edge may wear out and may not be able to exhibit sufficient performance. Furthermore, as described above, in a diamond sintered body, the rougher the diamond grain size, the better the wear resistance, but the more difficult it is to process. Diamond sintered bodies are produced by grinding with a diamond grindstone or by electrochemical processing methods such as electrical discharge machining, but when the diamond particles become coarse (not only by grinding), but because diamond particles are insulators, electrical discharge occurs. Processing is also difficult.

The present invention relates to a diamond sintered body that solves these problems.

Diamond sintered bodies are normally manufactured using diamond and Fee Nie Co, which can melt it, under extremely high temperature and high pressure conditions, where the diamond is stable.During this manufacturing process, diamond particles are bonded to each other and sintered. . Therefore, the diamond particles are mainly held by direct bonding with the diamond particles. In order to investigate the wear state of diamond sintered bodies for cutting, the present inventors performed cutting tests using a work material containing a large amount of hard substances, such as Al-high St alloy, and observed the wear state of the cutting edge. . As a result, rather than the diamond particles being worn away, the diamond particles fell off and were worn out. In order to improve the wear resistance of this sintered body, it is necessary to improve the retention of diamond particles, and we believe that the bond between diamond particles (hereinafter referred to as the diamond skeleton part) must be made stronger. It will be done.

An invention relating to developing a diamond skeleton portion and further increasing the diamond content in a diamond sintered body has already been described in US Pat. No. 4,268,276. This patent relates to manufacturing a sintered body using diamond particles with boron uniformly dispersed therein. Diamond particles in which boron is dispersed are easily deformed plastically, and normal diamond particles are sintered. It is stated that under the following conditions, it is possible to sinter at low temperature and low pressure, and the diamond skeleton portion also develops. When the present inventors conducted a test to confirm what is described in this patent, they were able to obtain a diamond sintered body that was dense and had a well-developed diamond skeleton. This diamond sintered body was used to create a cutting tool to cut an Al-25% Si alloy. Although the number of diamond particles falling off was reduced, there was a problem in that the diamond particles were heavily worn. In particular, when a sintered body was made using coarse diamond particles with boron uniformly dispersed therein and rock was cut, a remarkable difference appeared in the wear of the diamond particles. Diamond containing uniform boron is USP 4268, 27
6, it is easy to plastically deform, so it is advantageous for densification of diamond particles, but in terms of wear resistance, it is considered to be inferior to diamond particles that do not contain boron.

The present inventors have conducted extensive research in order to obtain a strong sintered body of a diamond skeleton without reducing the wear resistance of the diamond particles. As a result, diamond particles that contain or do not contain boron or are classified as 4as of the periodic table.
When sintering the carbide-added powder of 5a and 6a using an iron group metal as a catalyst, if a small amount of boron carbide, especially among borides, is added, the diamond skeleton part will grow large, and the diamond skeleton part and the diamond particles will grow. It has been found that it is possible to obtain a sintered body in which boron is present only around the . This diamond sintered body was machined to make a cutting tool, and /V-25%Si
When cutting the alloy, few diamond particles fell off. In addition, in order to investigate the wear resistance of the diamond particles themselves, coarse-grained diamond sintered bodies were prepared and rock was cut, but the wear resistance of the diamond particles did not deteriorate due to the inclusion of boron carbide.

The reason why the sintered body of the present invention has excellent wear resistance is considered to be as follows. Diamond particles are sintered under ultra-high pressure and high temperature through diamond melting and precipitation phenomena using catalysts such as iron group metals. When boron carbide is added, some or all of the boron carbide decomposes to form boride of iron group metals, lowering the melting point, and increasing the melt deposition rate, which increases the size of the diamond skeleton and increases the retention of diamond particles. It can be assumed that the power has improved. Furthermore, during sintering of diamond particles, dissolution and precipitation phenomena occur only at the contact surface between the diamond and the catalyst metal, so boron exists only in the diamond skeleton and around the diamond particles, and the strength of the diamond particles themselves does not decrease. Furthermore, in the sintered body of the present invention, by containing carbides of groups 4as, 5ae, and 6a of the periodic table as a part of the binder,
The heat resistance of the diamond sintered body can be improved. This is probably because the inclusion of carbide in the binder makes the coefficient of thermal expansion of the binder close to that of diamond. The sintered body of the present invention not only has excellent wear resistance but also can be subjected to electrical discharge machining, and the reason for this is presumed to be as follows. As mentioned above, a diamond sintered body is made up of diamond particles and a catalyst metal, but if the diamond particles are coarse, this is an insulator, so electrical discharge will not occur in this part and machining cannot be performed. USP 4 states that diamond particles have electrical conductivity if they contain a small amount of boron.
268, 276, since the sintered body of the present invention has an electrically conductive layer around the diamond particles, it can be processed by electrical discharge not only on the surface of the catalytic metal but also on the surface of the diamond particles. it is conceivable that.

Further, it is presumed that boron carbide is superior as a boride additive as shown in the first order. During sintering, some or all of boron carbide is decomposed into boron and carbon, but this is thought to be because the boron carbide and carbon are converted to diamond, and the remaining boron carbide has high hardness and excellent wear resistance. .

The content of diamond particles in the present invention is 70% by weight.
~9596 is preferred. If the diamond content is less than 70% by weight, the wear resistance of the sintered body decreases, and 959
If it exceeds 6, Fe, which acts as a catalyst during diamond sintering,
The content of e Nie Co etc. decreases, making it impossible to obtain a sintered body having a sufficiently developed diamond skeleton. The content of boron or boron carbide and boron present in the sintered body is 0.00596 to 1.0 by weight in the sintered body.
96 is preferred. If this content is less than 0.005%, the formation of the diamond skeleton portion is slow and the electrical discharge machinability of the diamond sintered body is also reduced. On the other hand, if the content of boron or boron carbide and boron exceeds 1.096, a layer containing a large amount of boron atoms is formed around the diamond skeleton part and diamond particles, resulting in a decrease in the wear resistance of the diamond sintered body. The diamond raw material used for the sintered body of the present invention has a diameter of 500 μm or less and may be either synthetic diamond or natural diamond. In particular, when wear resistance of the diamond sintered body is required, the particle size of the diamond particles is preferably 2 μm or more. On the other hand, if the diameter is 500 μm or more, electrical discharge machining becomes difficult even if a layer containing boron exists on the outer periphery of the diamond particles.

Periodic table 4a* 5ae 6a used in the sintered body of the present invention
Group carbides include Tics ZrCt HfCt
VCtNbCtTaC, WC(MoW)C can be used. Carbide and Fe e Nl e Co
The proportion of catalyst metals such as * or at least the amount necessary for carbide to exist as a solid during sintering is necessary. For example, when using WC and Co, the quantitative proportion of the cage and Co is 5096 by weight of the former. It is necessary to include the above.

In order to produce the diamond sintered body of the present invention, diamond powder as raw materials, boron or boride, and Fee.
A catalytic metal powder of Coo Nie Cr or a powder obtained by adding a carbide thereto is uniformly mixed using a means such as a ball mill. In addition, the inventors' earlier application (Japanese Patent Application No. 52-5
No. 1881), the pot and ball used in a ball mill are made of a sintered body of carbide and iron group metal, and at the same time diamond powder and boron or boride are mixed, the carbide and iron group metal are mixed from the pot and ball. There is also a method of mixing fine powder of a sintered body.

The mixed powder is placed in an ultra-high-pressure, high-temperature device and sintered under conditions where the diamond is stable. It is necessary to sinter at a temperature higher than the temperature at which the eutectic liquid phase appears of the catalyst metal, boron, and carbon used at this time, or a carbide added thereto. Alternatively, a mixed powder of diamond powder and metallic boron or boride, or a powder obtained by adding carbide powder thereto, may be placed in an ultra-high pressure and high temperature apparatus, and a catalytic metal such as Few Ntt Cot Cr may be introduced from the outside during sintering.

In addition to cutting tools, the sintered body of the present invention can also be used in excavating tools, dressers, and wire drawing dies. When used as a cutting tool or excavation tool, it is possible to bond the diamond sintered body to a support such as cemented carbide during ultra-high pressure sintering to improve the toughness of the diamond sintered body. In addition, when used as a wire drawing die, high pressure is generated on the inner surface of the sintered diamond die, especially when drawing high-strength wire rods. The diamond sintered body may crack in the vertical direction. In such a case, it is possible to prevent vertical cracking during wire drawing by surrounding the outer periphery of the diamond sintered body with a cemented carbide support and applying preload from the outer periphery of the diamond sintered body.

This will be explained in detail below using examples.

Example 1 Diamond particles having a particle size of 5 to 12 μm and diamond particles having a particle size of 2 to 6 μm were mixed in a ratio of 2:1. The weight ratio of this diamond powder, Co powder and boron carbide powder is 90:9.5:
0.5, a pressure of 55 Kb was first applied to a container made of Mo using an ultra-high pressure and high temperature device, and then the mixture was heated to 1450° C. and held for 15 minutes.

When this sintered body was taken out and its structure was observed, it was found that the diamond particles were firmly bonded to each other through the diamond skeleton. A cutting tool was created using this sintered body, and AI! ~25% Si was cut for 90 minutes at a speed of 850 ml/min. For comparison, a sintered body containing no boron carbide and a sintered diamond body having the same diamond particle size and uniformly containing B atoms were also prepared and subjected to cutting tests. During flank wear of diamond sintered body after cutting (Va
), the VB of the sintered body of the present invention was 0.050 &
llL, whereas the VB of the sintered body that does not contain boron carbide is 0.107 IuL, and the vB of the sintered body using diamond that uniformly contains boron is 0.0651 IuL.
It was u.

Example 2 Diamond powder having a particle size of 80 to 150 μm and boron carbide powder were mixed in a weight ratio of 99.9:0.1. Put this mixed powder in a container made of Mo, and put N on top of it.
An i-Cr plate was placed 1, and the container was placed in an ultra-high pressure and high temperature device and sintered at 55 Kb and 1450° C. for 15 minutes.

When this sintered body was taken out and observed, it was found that during sintering, Ni
-The liquid phase of Cr penetrated into the mixed powder and bound the diamond particles together. For comparison, particle size 80-150
A diamond powder of μm diameter was sintered with Ni-needle without using boron carbide, and a diamond particle having the same particle size and uniformly containing boron was sintered with Ni-Cr. When attempting to process the sintered bodies using a wire electrical discharge cutting machine in order to create cutting tools for cutting tests on these sintered bodies, it was found that the sintered bodies of the present invention and the sintered bodies of diamond particles uniformly containing boron were Although it was possible to process it, it was impossible to process a sintered body that does not contain boron, so it was cut by laser processing. Using these bits, cut into andesite with an outer diameter of 100 an at a speed of 60 m/min.

Cutting was performed for 90 minutes under the conditions of feed o, 5 mx/rotation, and wet conditions.

When the flank wear was measured after cutting, the VB of the sintered body of the present invention was 0.25jEj! On the other hand, the vB of a diamond sintered body uniformly containing boron was 0.045.
The diamond sintered body containing no boron carbide had a value of 0.0681jK.

Example 3 Diamond particles with a particle size of 80 μm and diamond particles with a particle size of 4θμ were mixed in a ratio of 4=1. This mixed powder and 84
The weight ratio of G powder and Co powder is 98:0.5 to 6.5.
It was blended into a finished powder.

This completed powder was subjected to ultra-high pressure sintering in the same manner as in Example 1. Next, this sintered body was processed using an electric discharge machine to make a dresser and dressed with a SiC-based grindstone. For comparison, a commercially available sintered body for dresser use was also tested, and the sintered body of the present invention had a 0.0
The wear was 8 m, whereas the commercially available sintered body for dressers was worn 0.2 fUIL.

In addition, the locations where boron is present in the sintered body of the present invention were
Investigation using an ion microanalyzer (ion microanalyzer) and an E PMA (electron, probe, microanalyzer) revealed that boron was present in the diamond skeleton, the outer periphery of the diamond particles, and the binder, but was not contained within the diamond particles. It wasn't.

A finished powder shown in Table 1 was prepared. This mixed powder was subjected to ultra-high pressure sintering in the same manner as in Example 1. Step 1: Process these sintered bodies to create a cutting tool bit, and cut cordierite once at 80-/min, depth of cut Q, 5 #
IjlL, feed Q, 3 m/rotation, wet cutting for 80 minutes.

The results are also shown in Table 1.

Example 5 0-1μ diamond particles and 84C powder in a weight ratio of 9
7=3 blend, using WC-Co pot and pole,
Mixed in a ball mill. Analysis of the powder after mixing revealed that
Diamond: B4C: WC: Co has a weight ratio of 8
The ratio was 7.8:2.7:8:2. This powder and diamond with a particle size of 20 to 80μ are mixed in a ratio of 1=4, and after filling a container made of cemented carbide, Co
The plate was placed and sintered in an ultra-high pressure and high temperature apparatus.

This sintered body was processed into a die with a hole diameter of 0.175 mm, and a brass-plated steel wire (steel cord) was processed at a speed of 10
The wire was drawn at a speed of 00 m/min. For comparison, commercially available particle size 20-3
A die made of 0μ diamond sintered body was also made and tested at the same time.

The sintered body of the present invention could be drawn to 2.8 t, whereas the commercially available sintered body could only be drawn to 0.9 t.

Procedural amendment Written by Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of the case, 1982 Patent Application No. 807892, Name of the invention, Diamond sintered body for tools and its manufacturing method 8, Person making the amendment Relationship with the case Patent applicant Address 5-15 Kitahama, Higashi-ku, Osaka Name (21
3') President of Sumitomo Electric Industries, Ltd. Tetsube 4, Agent address: Sumitomo Electric Industries, Ltd., 1-1-8 Shimaya, Konohana-ku, Osaka) 6. Detailed description of the invention in the specification subject to amendment Column 7, Contents of amendment (1) Page 7, line 1 of the specification, “(not only grinding)” was changed to “not only grinding”
Correct.

(2) Same book, page 17, line 16, Correct IO,045j to rO,45J.

(3) Same book, same page, line 18, Correct r　O,063J to r　O,63j.

(4) Table 1 on page 19 of the same book is corrected as shown in the attached sheet.

Claims (9)

[Claims] (1) Diamond particles with a particle size of 500 μm or less contain 70 to 9596 by weight and 0.005 to 1.0% of boron, which is produced by the decomposition of part or all of boron carbide, and the remainder is F.
eeNt A tool made of an alloy of one or more of Co+Cr, characterized in that boron produced by decomposition of part or all of boron carbide is present in the joints between diamond particles and in the outer periphery of the diamond particles. Diamond sintered body. (2) The diamond sintered body for tools according to claim 1, wherein the diamond particles have a particle size of 2 to 500 μm. (3) Diamond particles with a particle size of 500 μm or less contain 70 to 95% by weight of boron produced by decomposition of part or all of 0.005 to 1.096 boron carbide, and the remainder has a particle size of 1 μm or less. It is made of an alloy of one or more of the carbides of groups 4ae, 5ae, 6a of the Table of Contents and Fee Nip Coe Cr, and the boron produced by decomposition of some or all of the boron carbide acts as a bond between diamond particles and in the diamond particles. A diamond sintered body for tools, which is characterized by being present on the outer periphery. (4) The diamond sintered body for tools according to claim 8, wherein the diamond particles have a particle size of 2 to 500 μm. (5) Mix diamond particles with a diameter of 500 μm or less and boron carbide powder, and place -FA +N1J on top of this mixed powder.
After placing an alloy plate of one or more types of Co*Cr, Fee Nis Coa is formed under high temperature and pressure at which the diamond is stable using an ultra-high pressure and high temperature equipment using a solid pressure medium.
The diamond particles are sintered by infiltrating the liquid phase of one or more alloys of Cr between the diamond particles, and the diamond particles are 500 μm or less in weight and are 70 to 9596 and 0.005 to 196 in weight.
Contains boron produced by the decomposition of some or all of the boron carbide, and the remainder consists of one or more alloys of Fee Nip Cot Cr. A method for manufacturing a diamond sintered body for a tool, in which a diamond sintered body exists in the joints between diamond particles and in the outer periphery of the diamond particles. (6) Diamond particles with a particle size of 500 μm or less, boron carbide powder, and one or more alloy powders of Fe + Nts Coo Cr are mixed, and this mixed powder is heated using an ultra-high pressure and high temperature device using a solid pressure medium. Diamond particles of 500 μm or less are sintered under high temperature and high pressure where diamond is stable, and the weight is 70-9.
5% and 0.005 to 1.096 containing boron generated by decomposition of some or all of the boron carbide, and the remainder is FeeN.
Diamond sintered for tools, which is made of an alloy of one or more of Cow Cr and in which boron, which is produced by decomposing part or all of boron carbide, is present in the joints between diamond particles and in the outer periphery of the diamond particles. How the body is manufactured. (7) Diamond particle size is 2. The method for manufacturing a diamond sintered body for tools according to claim 5.6, wherein the diamond sintered body has a diameter of 500 μm. (8) Diamond particles and boron carbide powder with a particle size of 500 μm or less and Periodic Table No. 4a #5a #6a
Mix the carbide powder of the above group, and add Few
After placing an alloy plate of one or more types of Nts Co5Cr, using an ultra-high pressure and high temperature device using a solid pressure medium, Fe
500μ characterized in that the diamond particles are sintered by infiltrating the liquid phase of one or more alloys of N15CooCr between the diamond particles.
70-95% by weight of diamond particles less than 0.2 m in size.
005 to 1% of boron carbide containing boron generated by decomposition of part or all of it, the remainder being carbide of group 4ae5a+6a of the periodic table with a particle size of 1 μm or less and Fe + Ni eCo
A diamond sintered body for tools is made of an alloy of one or more types of tCr, and boron produced by decomposition of a part or all of boron carbide is present in the joints between diamond particles and the outer periphery of the diamond particles. Production method. (9) Boron carbide powder with diamond particles having a particle size of 500 μm or less, carbide powder of Group 4AS5A+6A of the periodic table, and alloy powder of one or more types of Fee Nts Coo Cr were mixed, and this mixed powder was mixed using a solid pressure medium. Diamonds are made cheaper by using ultra-high pressure and high temperature equipment.
500 characterized by being sintered under constant high temperature and high pressure.
Diamond particles with a particle size of 1 μm or less contain 70-95% and 0.005-1% by weight of boron generated by decomposition of some or all of boron carbide, and the remainder has a particle size of 1 μm or less. *6a group carbide and Fe+Ni
* A tool made of one or more alloys of Coo Cr, characterized in that boron produced by decomposition of part or all of boron carbide is present in the joints between diamond particles and in the outer periphery of the diamond particles. A method for producing a diamond sintered body for use. The method for manufacturing a diamond sintered body for tools according to claim 8.9, wherein the GO diamond particle size is 2 to 500 μm.