JPS5935066A - 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] [Technical Background] Currently, the content of diamond (h) is 70% or more.
- Sintered bodies in which diamond particles are bonded to each other are sold and used for cutting nonferrous metals, plastics, and ceramics, dressers, drill bits, and wire drawing dies. In particular, when these nine diamond sintered bodies are used as dies for cutting nonferrous metals or drawing relatively soft wires such as copper wire, their performance is extremely excellent. Normally, these diamond sintered bodies use iron group metals such as Co, which are catalysts during diamond synthesis, to bind diamond particles, so if they are heated to a temperature of 600°C or higher, the diamonds will graphitize and deteriorate. It has its drawbacks. A method for improving the heat resistance of a diamond sintered body is to remove iron group metals such as Co, which promote graphitization of diamond during heating, as described in JP-A-53-1145891. However, if iron group metals such as Co are eluted from the diamond sintered body, the strength of the diamond sintered body will be 2.
It decreases by 0-30%. In particular, when a diamond sintered body is used as a bit, strength, wear resistance, and heat resistance are required. Due to the lack of strength of the body, the cutting edge will break and the life will be short. The inventors of the present invention have conducted extensive research in order to develop a diamond sintered body that has high strength, good wear resistance, and excellent heat resistance.

[Disclosure of the invention]

As a result of research, coarse diamond particles with a particle size of 37,771 or more accounted for 20-85% in a 4-ton volume, and the remainder was a binder of 10-85%.
It consists of 79% by volume and 1% or more of voids, less than 15%, and the composition of the binder is 60 to 90% of ultrafine diamond particles with a particle size of 1 μm or less. Carbide 85-5% by volume and I
It has been found that a diamond sintered body made of an iron group metal with a volume percent of O or less has toughness, wear resistance, and heat resistance. The reason why the sintered body of the present invention has good toughness, wear resistance, and heat resistance can be inferred as follows.

As shown in FIG. 1, the strength of the diamond sintered body decreases as the grain size increases. Fine-grained diamond sintered bodies have high transverse rupture strength and excellent toughness, so the cutting edge is less prone to breakage, but individual particles are held together by small diamond skeletons, so the bonding force between individual particles is weak. .

Therefore, individual particles tend to fall off during cutting, which is thought to result in poor wear resistance. On the other hand, coarse-grained diamond sintered bodies are held by a large skeleton, and the bonding force between individual diamond particles is strong, so they have excellent wear resistance. If this occurs, it will propagate and the cutting edge will easily break, resulting in poor toughness.

Since the sintered body of the present invention is made by sintering coarse-grained diamond using a binder containing fine-grained diamond, it is thought to have both the high toughness of fine-grained diamond and the good wear resistance of coarse-grained diamond. . In addition, the sintered body of the present invention can be used as part of the binding material according to periodic table 4, a r 5a * 6.
Although group a carbides and iron group metals are used, it is mainly the iron group metals that are eluted by acid treatment, and because the content is small, fewer vacancies are created, and the strength decreases after the iron group metals are eluted. There are few. The first reason for the improved heat resistance is that graphitization of diamond was suppressed due to the elution of iron group metals.

Further, in a diamond sintered body containing an iron group metal, cracks occur when heated due to the difference in thermal expansion between the diamond and the iron group metal, but the elution of the iron group metal suppresses the generation of these cracks. The thermal expansion coefficient of carbide, for example wc, is 4 to 5 x 10
-6, which makes it difficult for cracks to occur due to thermal stress.

The coarse diamond grain size in the sintered body of the present invention is 3 μm.
The above is preferable. Coarse diamond grain size is 8μtn
If it is less than that, the wear resistance will decrease. Especially lOμm~]0
The case where 0 μn+ diamond particles are used has the best toughness and wear resistance.

The content of coarse diamond is preferably 20 to 85%.

When this content is less than 20%, wear resistance decreases, and 8
If it exceeds 5%, toughness decreases.

The number of pores is preferably 1% or more and less than 5% by volume of the sintered body. When the pore content is 5% or more, the strength of the diamond sintered body is significantly reduced. Moreover, if it is less than i96, the amount of iron group metals contained will be large and the flame resistance will not be good.

The ultrafine diamond particles used as a binder are l 1
ltn or less, preferably 0,511711 or less. When the particle size exceeds 1 μnZ, the toughness of the sintered body decreases. The content of ultrafine diamond particles is preferably 60 to 90% by volume in the binder. When the content is less than 60%, the wear resistance of the binder decreases. Moreover, when it exceeds 90%, the toughness of the bonding material decreases.

The content of carbides of the periodic law 4.a + 5 a r 6 a group is preferably 5 to 35% by volume in the binder. If this content is less than 5%, diamond particles of 11m or less will grow and the iron group metal content will substantially increase, leading to a decrease in heat resistance and a decrease in strength due to an increase in pores after elution. becomes a factor. If this content exceeds 35%, the content of ultrafine diamond particles decreases and the wear resistance of the binder decreases.

One company containing iron group metals should preferably have a capacity of 10% or less in the binder. If the content of iron group metals exceeds 10%, the heat resistance will deteriorate.
I can't hope for a second one.

The sintered body of the present invention has excellent toughness, wear resistance, and heat resistance, especially when the carbide is WC or (Mo, W)C having the same crystal structure.

In addition, the sintered body of the present invention has a weight of 0.005 to 0 by weight of the sintered body.
．． ] When containing 5% boron or boride, its performance is further improved. Normally, diamond particles are produced by melting diamond using catalysts such as iron group metals under ultra-high pressure and high temperature.
Sintered by precipitation phenomenon. When boron or a boron compound is added, borides of iron group metals are produced, which lowers the melting point. At the same time, the melt deposition rate increases, which causes the bond between diamond particles (diamond skeleton) to grow, which reduces the holding power of the diamond particles. It can be assumed that this has improved. If the content of boron or boride is less than 0.005%, the formation of the diamond skeleton portion will be slow. On the other hand, if the boron or boride content exceeds 0.15%, a large amount of boron will enter the diamond skeleton, reducing the strength of the diamond skeleton.

The diamond raw material powder used for the sintered body of the present invention is 3μ
Diamond particles larger than m and 1μ? It is micron powder of n less than 1, j preferably 0.5 ttm or less.

Either synthetic diamond or natural diamond may be used.

This diamond powder and the periodic table 4. a+5a+6a
The carbides of the Fe+Co+Ni group and the iron group metal powder of Fe+Co+Ni or a powder obtained by adding boron or boride thereto are uniformly mixed using a means such as a ball mill. This iron group metal may be infiltrated during sintering without being mixed in advance.

In addition, as in a previous application by the present inventors (Japanese Patent Application No. 52-51-51381), sintering of carbides of groups 4 and 5a of the periodic table and iron group metals by mixing pots and balls during ball milling has been proposed. There is also a method in which diamond powder is prepared in a ball mill and, at the same time, fine powders of carbides of groups 4a+5a l 6a of the periodic table and sintered bodies of iron group metals are mixed in from a pot and ball.

The mixed powder is placed in an ultra-high-pressure device and sintered under conditions where the diamond is stable. The appearance of a eutectic liquid phase between the iron group metal used in this process and compounds such as carbides must be sintered using a temperature tool.

Although the ratio of compounds such as carbides and iron group metals that serve as the bonding phase of diamond in the sintered body cannot be unambiguously determined, it is necessary that the amount is at least sufficient for the compound to exist as a solid during sintering. For example, when WC is used as a compound and Co is used as a bonding metal, the quantitative ratio of WC and Co must include 50% or more by weight of m1.

The diamond sintered body thus produced is placed in an acid, such as aqua regia, which corrodes iron group metals and forms scales, eluting iron group metals and creating pores.

In addition to bits, the sintered body of the present invention can be used in wire drawing dies, ceramics, cutting tools, and the like.

This will be explained in detail below using examples.

Example].

Synthetic diamond powder with a particle size of 0.5/l and WC and Co powders were ground and mixed using a pot and ball made of WC-Co cemented carbide. The composition of the obtained mixed powder was 80% by volume of fine diamonds with an average particle size of 0.3 μm.
, WCl 2% by volume, and Co 8% by volume. This mixed powder and diamond powder having a particle size of 20 to 30 l1m were mixed in a volume ratio of 75:25. This finished powder is Mo
The pressure was first increased to 55% using an ultra-high pressure device.
r<b>, followed by heating to 14.50°C and holding for 30 minutes. This sintered body is taken out from the container and heated/
The sample was placed in aqua regia for 150 hours to elute co. C
Analysis of the composition of the diamond sintered body after O elution revealed that Co + WC was 1.2% by volume in the binder, and
It contained 11.8% by volume. The volume of pores in the sintered body was 1.7%. This diamond sintered body was heated in vacuum to 1000°C for 30 minutes, and the strength was determined by a transverse rupture test. The results are shown in Table 1. For comparison, the strength of the diamond sintered bodies shown in Table 1 was also measured at the same time.

A binder powder shown in Table 2 was prepared. The fine diamond particles used were those with a diameter of 0.3 μm. This binder and coarse diamond particles were mixed in the proportions shown in Table 3 to prepare a finished powder at °C.

3 After sintering these finished powders in the same manner as in Example 1,
The diamond sintered body was taken out and heated in aqua regia for 10 minutes.
(The treatment was carried out for 1 hour. The content of pores in the sintered bodies after iron group metal elution is also shown in Table 3.Next, these sintered bodies were used to create cutting tools for cutting, and granite was cut at 50 m/min. Dry cutting was performed for 30 minutes at a speed of min. The results are also shown in Table 3.

Example 3 Diamond particles with an average particle size of 0.511 m and WClCO
and boron powder were pulverized and mixed using a WC-Co cemented carbide bot and ball. The composition of the obtained mixed powder was 81% by volume of fine diamond with an average particle size of 0.3μ, W
The contents were 10% by volume of C, 9% by volume of Co, and 1.0% by volume of boron. This mixed powder and Diacene 1:particles having a particle size of 30 to 4 Q/7nl were mixed in a volume ratio of 2:8 to prepare a finished powder. When the boron content was measured, it was 0.
It was 128%.・This next diamond sintered body is 1.5 m in diameter, m-,
After processing it into a cylinder of JI SA3, it was heated for 15 minutes in aqua regia.
Treated for 0 hours.

The porosity after treatment was 1.5%. This sintered body was attached to a steel shank.
A matrix of high melting point and high hardness made of mixed powder of Cu is
It was sintered and fixed at 000°C to create a surface set core bit. For comparison, C is a commercially available sintered body made of diamond particles of 40 to 60μ and is a binder.

A core bit of the eluted material was also prepared in the same manner. With these bits - axial compressive strength 1800.

Although it was still possible to excavate 50 m at a speed of 10 crn/min, the bit using a commercially available diamond sintered body reached the end of its life after digging 301 m at a digging speed of 8 α/min.

[Brief explanation of the drawing]

Figure 1 shows the strength (transverse rupture strength) of a diamond sintered body.
This shows the relationship between diamond grain size and diamond particle size. Figure 71, 2 ( = 1 [ Diamond grain & (, Llm)

Claims (1)

[Scope of Claims] (1) Coarse diamond particles with a particle size of 3μ771 or more account for 20 to 85% by volume, and the remainder consists of a binder of 10 to 79% by volume and 1% or more of voids, less than 15% of the binder. The composition is 60-90% by volume of ultra-fine diamond particles with a particle size of 1/7F11 or less, 35-5% by volume of carbides of Group 4, A + 5A, L 6a of the Periodic Table of 177 m or less, and iron group metal IO. Diamond sintered body for tools with a capacity of % or less. (2) Coarse diamond particles with a particle size of 311 m or more account for 20 to 85% of the total, and the remainder is a binder of 10 to 79 m.
Ultra-fine diamond particles with a particle size of 1μ or less, consisting of 1% or more and less than 5% of voids, and the binder has a particle size of 1 μm or less
0 to 90% and 1 μm or less Periodic Table 4.a + 5a
+ +3a group carbide 35-5 capacity, iron group metal 1
0% by volume or less and consisting of boron and/or boride,
Boron and/or boride content is 0 by weight of sintered body
．． A diamond sintered body for tools having a content of 0.005 to 0.15%. (3) The particle size of coarse diamond particles is 10 μm or more10
0 μII+ Claims (1) and (
2) The diamond sintered body for tools described in item 2). (4) Carbide of groups 4a+5a+6a of the periodic table is W
Has the same crystal structure as C or WC (Mo, W)
A diamond sintered body for tools according to claims (1), (2), and (3), which is C. (5) Diamond powder of 3 μm or more, ultrafine diamond powder of 1/1 m or less, mixed powder of carbides of groups 4, a, 5a + 6a of the periodic table and iron group metals of 1 μm or less are prepared, and ultra-high pressure and high temperature equipment is used. A sintered body is created by hot pressing under high temperature and pressure at which the diamond is stable.
By acid-treating the sintered body, coarse diamond particles of 3μI11 or more, which are characterized by eluting - part of the iron group metal, account for 20 to 85% of the volume, and the remainder is bonded @10 to 85% by volume. Consisting of 79% by volume and 1% or more and less than 5% voids,
The composition of the binder is ultrafine diamond particles with a particle size of 1 μm or less, and the capacity is 0 I) = 90% and l 7 (Ill
Carbides 35 to 5 of Groups 4a+5a+6a of the periodic table below
[volume 111% and iron group metal] 0 volume % or less I: Method for manufacturing a diamond sintered body for tools. (fi) 3μ71+ diamond powder, l
Ultrafine diamond powder less than ltm l/(++
1 Periodic Table 4a below! 5a + (ia
A mixed powder of iron group carbides, iron group metals, boron and/or borides is prepared, and a sintered body is created by hot pressing under high temperature and pressure at which diamond is stable using an ultra-high pressure and high temperature equipment. It is characterized by eluting a part of the iron group metal by treating the aggregate with acid.3 Coarse diamond particles of 11m or more in size account for 20 to 85% of the body, and the remainder is bonded 4410-79 volume. : 112% and 1% to less than 5% voids, and the bond (A is ultrafine diamond particles with a particle size of 1 μm or more) is 6 (1 to 90% and l)
35 to 5 volumes of carbide of group 4, a+5a+ria of the periodic table below 1tm! '4t%, iron group metal JO capacity It%
Itin and boron and /-! : Made of bamboo boride, containing boron and/or boride: 11: is the sintered body 11
℃ (1,005~0.15%) Manufacturing method of diamond sintered body for tools.
114. of Claims (5) and (6), which is equal to or more than lQQ/lnl. A method for producing a diamond sintered body for use. (8) Periodic (Itomo No. 4, a + 5a r 6a group carbide has WC or the same crystal structure as this (
Claim No. (5) which is Mo, W) C, (
6), the method for producing a diamond sintered body for tools as described in (7).