JPS5891056A - Diamond sintered body for tools 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 In recent years, with the development of ultra-high pressure sintering technology, various diamond sintered bodies have been manufactured and sold. Unlike single-crystal diamond tools, these diamond sintered bodies are less prone to breakage due to creases and can be made in large sizes, making them popular for their use in cutting non-ferrous metals, wire drawing dies, and drilling tools. I am making money. However, when these diamond sintered bodies are used under severe conditions, such as when drilling high-strength rocks or drawing hard wire rods, fine-grained diamond sintered bodies tend to wear out due to diamond particles falling off. On the other hand, in the case of a coarse-grained diamond sintered body, although the number of diamond particles falling off is small, since each diamond particle in the sintered body is a single crystal, there is a problem in that the particles become interfolded and chipped. The present invention aims to improve this drawback to obtain a diamond sintered body with excellent wear resistance and toughness. First, the present inventors investigated a coarse-grained diamond sintered body with fewer diamond particle defects. If the coarse diamond grains are single crystals and cause folds and defects, it would be better to use polycrystalline diamond grains, which are strong aggregates of fine diamond grains, instead of using single crystals as the diamond grains. Therefore, the particle size is an aggregate of fine diamond particles containing almost no binder with a particle size of 0.01 ttrr]
A diamond sintered body was produced using only the diamond particles obtained by the shock wave method of No. 511 by the method disclosed in Japanese Patent Publication No. 52-12126. When the structure of this diamond sintered body was observed, as shown in Figure 1, the polycrystalline diamond particles had abnormal grain growth and were non-uniform, and the diamond particles produced by the shock wave method were found to be satisfactory. I found out that there isn't.

The reason why these diamond particles grow abnormally is because each diamond particle is extremely fine, measuring 0.0111 m, and has a high surface energy.
This is probably due to the rapid growth of the individual grains and their mutual bonding. Therefore, it is thought that grain growth can be suppressed by preventing these grains from directly joining together.

The substance that prevents this direct bonding must be a substance that strongly bonds with diamond and has excellent strength and wear resistance.

The inventors have conducted repeated research on this binding material.

As a result, fine diamond particles of 1 μm or less and particles 4a and 5a of the periodic table of 1 μm or less were used as a binder.

Group 6a carbides, nitrides, borides or solid solutions or mixtures thereof crystals and iron group metals, or 1 μm
Periodic table number 4 below. a, 5a, 6a group carbides,
It has been discovered that grain growth can be suppressed and a sintered body with a uniform structure can be created by using nitrides, borides, solid solution mixture crystals thereof, and iron group metals.

The binding materials for the sintered body of the present invention that are effective in suppressing grain growth are carbides, nitrides, and borides of Groups 4a, 5a, and 6a of the periodic table, or solid solutions or mixtures thereof. Grain growth of diamond particles occurs when there is an iron group metal that dissolves the diamond under high temperature and high pressure conditions, and is due to this dissolution precipitation phenomenon.
If the ratio of carbides and metals of groups A and 6a is greater than that corresponding to the eutectic composition, the carbides will remain in solid form and the effect of suppressing grain growth will be improved. In particular, carbides with WC or the same crystal structure as WC (Wo,
W)C had the greatest effect.

In the sintered body of the present invention, the content of polycrystalline diamond particles obtained by the shock wave method is preferably 20 to 85% by volume. If the content of polycrystalline diamond is less than 20%, the wear resistance of the diamond sintered body decreases rapidly, making it impractical.

Further, when the content of polycrystalline diamond particles exceeds a coefficient of 85, polycrystalline = 6 = diamonds come into direct contact with each other and grains grow.

Furthermore, as described above, the binder must have excellent wear resistance, and by incorporating fine diamond particles into the binder, the wear resistance is greatly improved. The particle size of the diamond particles contained is preferably 17 tm or less. If the particle size of the diamond particles is 1J11rL or more, the diamond particles may not be uniformly dispersed in the binder or the toughness of the binder may decrease. The content of the diamond particles is preferably 95 or less by volume in the binder. If the content of diamond particles exceeds 95%, the binder becomes brittle, or the content of carbides, nitrides, borides, etc. in groups 4a, 5a, and 6a of the periodic table decreases, resulting in diamond particles in the binder. Not only that, but the polycrystalline diamond particles also grow, making it impossible to obtain the desired performance. In particular, when wear resistance of the binder is required, the content of fine diamond particles in the binder may be increased by 2.
It is better to set it to 0 or more.

The diamond powder used as the binding material of the present invention is 11
Micron powder with a size of 1 m or less can be either synthetic diamond or natural diamond.

3 μm obtained using this diamond powder and shock wave method
The above-mentioned polycrystalline diamond particles, one or more of the above-mentioned arsenide powders, and iron group metal powders of Fe, Co, and Ni 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, the inventors' earlier application (Japanese Patent Application No. 52-5138
As in No. 1), the bots and balls used in a ball mill are made from a compound such as carbide and a sintered body of iron group metal.
There is also a method in which diamond powder is ground in a ball mill and, at the same time, a compound such as a carbide and a finely measured powder of a sintered body of an iron group metal are mixed in from a bot and a ball.

The mixed powder is placed in an ultra-high-pressure device and sintered under conditions where the diamond is stable. It is necessary to sinter at a temperature higher than the temperature at which a eutectic liquid phase appears between the iron group metal used at this time and a compound such as a carbide. For example, using TiC as a compound,
When Co is used as the iron group metal, it is approximately I26 under normal pressure.
A liquid phase forms at 0°C. Under high pressure, this eutectic temperature is thought to rise by several tens of degrees Celsius. Therefore, in this case, sintering is performed at a temperature of 1300°C or higher. Although the ratio tζ of compounds such as carbides and iron group metals that serve as binding materials for diamond in the sintered body cannot be determined unambiguously, 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 parts or more by weight of the former.

When the diamond sintered body of the present invention is used to draw a high-strength wire rod, high pressure is generated on the inner surface of the sintered diamond die. The diamond sintered body may crack in the vertical direction.

In such cases, it is possible to prevent vertical cracking during wire drawing by surrounding the outer periphery of the diamond sintered body with a support such as cemented carbide and applying preload from the outer periphery of the diamond sintered body. .

The sintered body of the present invention can be used not only for dies but also for cutting tools and excavating tools. In this case, in order to further improve the toughness of the diamond sintered body, it is also possible to bond it to a support such as cemented carbide during ultra-high pressure sintering.

This will be specifically explained below using examples.

Example 1 Synthetic diamond powder with a particle size of 0.5μ and WC and CO powders were pulverized and mixed using a WC-Co cemented carbide bot and ball. The composition of the obtained mixed powder was 80 volumes of fine diamond with an average particle size of 0.3 μm, 2 volumes of WCl, and 8 volumes of Co.

This mixed powder and polycrystalline diamond obtained by the shock wave method with a particle size of 15 μm were mixed in a volume of 4·=6. The finished powder was packed in a WC-IQ%co container, and a pressure of 55 Kl was first applied using an ultra-high pressure device, followed by heating to 14.50°C and holding for 20 minutes.

When the sintered body was taken out and its structure was observed, as shown in FIG. 2, the polycrystalline diamond with a grain size of 15 μm had not grown and was firmly bonded to the binder.

A sintered diamond die with a hole diameter of 0.175 was made using this sintered body. For comparison, a diamond sintered die was also prepared in which commercially available single crystal diamond particles having a grain size of 30 to 60 μm were bonded with CO. Linear speed of 800m/min using these dies
, Brass-plated steel wire was drawn in lubricating oil. The die manufactured from a commercially available diamond sintered body is 4.50 Ky,
At the time of wire drawing, vertical scratches appeared on the wire surface and the wire surface reached the end of its service life, whereas in the sintered body of the present invention, even after 3000 Np wire drawing, there were still few scratches on the wire surface.

Example 2 A bonding material shown in Table 1 was prepared. As the fine diamond, one of Q, 5 JirrL was used.

This binder and polycrystalline diamond particles having a particle size of 3 μm or more were mixed in the ratio shown in Table 2 to prepare a finished powder. These finished powders were sintered in the same manner as in Example 1, and then their structures were observed. Grain growth of diamond particles was observed in the sintered body.

Next, a die with a hole diameter of 0.25 wm was prepared using these sintered bodies, and a brass-plated steel wire was drawn in lubricating oil at a linear speed of 800 m/min. The results are also shown in Table 2.

For comparison, a commercially available diamond sintered body with diamond particles bonded with Co and a cemented carbide die with a grain size of 30 to 60 tim were also created and tested at the same time. They were 1200 KP and 4.OOπノ, respectively.

Example 3 A binder powder shown in Table 3 was prepared.

Table 8 This binder powder and polycrystalline diamond particles obtained by the shock wave method with a particle size of 3 μm or more were mixed in the proportions shown in Table 4 to prepare a finished powder. This finished powder-14,- powder was filled into an MO container after putting a WC-7% Co disc therein, and heated to 55 Kl at 1450°C using an ultra-high pressure device.
Sintered for 0 minutes. A cutting tool was created using this sintered body, and the granite with a -axial compressive tension of 1300 K9/an was cut at a speed of 35 m/min, depth of cut of 1 + l1111, feed of 0.
．． Cutting was performed using cutting fluid at 5+nm/rev for 60 minutes.

The results are also shown in Table 4. For comparison, a commercially available diamond sintered body for excavation tools in which diamond particles with a grain size of 100 JttrL were bonded with CO was also tested, but the cutting edge broke off after 11 minutes of cutting.

Table 4゜Example 1 The binder powder prepared in Example 1 and polycrystalline diamond particles obtained by the shock wave method with a particle size of 50 μnL were mixed in a ratio of 7=3, and this finished powder was sintered in the same manner as in Example 3. Tie,
A drill bit for excavation was made using this sintered body, and the rotation speed of andesite was 2 Q m for 7 minutes, and the drilling rate was 10 to 15 (7).
7 minutes Excavation using muddy water.

For comparison, the commercially available sintered diamond bit used in Example 3 was also prepared and tested under the same conditions. As a result, the sintered body of the present invention could not excavate 50 m, whereas the commercially available sintered diamond bit could only excavate 10 n'L.

Example 5 The binder powder prepared in Example] and the polycrystalline diamond powder obtained by the particle size 3 lt shock wave method were mixed in a volume ratio of 60
: Mix 4.0 and pack this powder into a container made of 'Fa.53 K+), 14. Ultra-high pressure sintering was carried out at oo'c for 10 minutes. This sintered body is used to create a cutting tool,
Station -25 S+ at speed 300 m/m 1st, depth of cut 0.
5. Cutting was carried out for 60 minutes at a feed rate of 0.2 towns/rcv.

For comparison, diamond particles of 3 to 8μ71L were used as C.

Tests were also conducted on commercially available diamond sintered bodies bonded with As a result, the work surface cut with the sintered body of the present invention was extremely smooth, with flank wear of 0.03-m, whereas the work surface of the commercially available sintered body was rough and the flank wear was 0.03-m. Wear "1" was 0.05 mm.

[Brief explanation of the drawing]

Figure 1 is a photograph of the structure of a diamond sintered body created by infiltrating polycrystalline diamond particles obtained by the shock wave method with a binder, and Figure 2 is a photograph of the structure of the diamond sintered body of the present invention. . 17- Yoshi 1 Figure 2 0Q

Claims (1)

[Claims] (J,) Contains polycrystalline diamond particles obtained by a shock wave method with a grain size of 3 μm or more, with a volume of 20 to 85 modulus, and the remainder contains ultrafine diamond particles with a volume of 1 μm or less. Sections 20-95 and Periodic Laws 4a, 5a, 6 of 1 μm or less
A diamond sintered body for tools comprising a binder composed of group A carbides, nitrides, borides, solid solutions or mixture crystals thereof, and iron group metals. (2. In the sintered body according to claim 1 or 2, No. 4a of the periodic table used as a part of the binding material,
A diamond sintered body for tools, characterized in that the ratio of carbides of group 5a and 6a metals to iron group metals is higher than that corresponding to the eutectic composition thereof. (3) Claims 1, 2, or 3, characterized in that the carbide used as part of the binder is WC or (Mo, W)C having the same crystal structure as WC. The described diamond sintered body for tools. (4) Polycrystalline diamond powder obtained by the shock wave method with a particle size of 8 μm or less, ultrafine diamond powder with a particle size of 1 μm or less, and particles 4a and 5a of the periodic table with a particle size of 1 μm or less. A mixed powder of 6a group metal carbides, nitrides, borides, and solid solutions or mixtures thereof and iron group metals is prepared, and an ultra-high pressure and high temperature device is used to heat the diamond at a high temperature at which it is stable. Polycrystalline diamond particles obtained by the shock wave method with a grain size of 3111 rL or more, characterized by hot pressing under high pressure, have a volume of 20 modulus or more 85
Ultrafine diamonds with a volume of 20 to 95 and 1μnL or less are ultrafine diamonds with a volume of 20 to 95 and 1 μm or less, and the remainder is 1 μm or less. a. A method for manufacturing a diamond sintered body for a tool, which is made of a binder made of a carbide, nitride, or boride of a group 5a or 6a metal, or a solid solution or mixture crystal thereof, and an iron group metal. (5) Claim 4. Prior to the manufacturing method described in section 4, the periodic table 4.
a, 5a, using a mixed powder in which the ratio of Ga group metal carbide and iron group metal is larger than that corresponding to the eutectic composition, A method for producing a diamond sintered body for tools, characterized by sintering ultrafine diamond while suppressing grain growth. (6) Diamond sintering for tools according to claim 44 or 5, characterized in that the carbide used as the binder is WC or (He4o, W)C having the same crystal structure as WC. How the body is manufactured.