JPS6034514B2 - Manufacturing method of diamond sintered body - Google Patents

Description

[Detailed Description of the Invention] Diamond sintered bodies have been developed in recent years, and their position as a material for tools is gradually becoming more established.
Currently used for line drawing dies, cutting tools, etc.

There are not many problems when used as a cutting tool, but when used for wear-resistant applications such as wire drawing dies, the metal phase contained as a binder often becomes a problem. . Wear progresses from this metallic phase, or the presence of the metallic phase cancels out one of the excellent properties of diamond, which is its poor docking resistance. For this reason, sintered bodies made only of diamond have been proposed, but obtaining them requires ultra-high pressures and high temperatures that cannot be obtained with ultra-high pressure and high-temperature equipment that is currently available industrially. isn't it. Therefore, the present inventors have conducted various studies on diamond sintered bodies that have improved these drawbacks. For example, we considered using a nonmetal as a binding material, but it turned out that it was difficult to obtain a sintered body with sufficient strength. When a metal such as nickel is used as a catalyst for converting graphite to diamond, part of the graphite and diamond dissolves in the molten metal, and the sintering results in so-called liquid phase scaling. Metals such as nickel do not have good wettability with diamond, as in the case of WC crystals and molten cobalt, so a skeleton made of diamond is formed during liquid phase burning, and the metal exists in the form of a pool in this skeleton. I will do it. When the size and amount of this accumulation is large, the above-mentioned drawbacks occur. The present inventors considered reducing the size and amount of this area. They discovered that the cause of this buildup was during the diamond particle embossing process. Generally, when creating a diamond compact as described above, pressure is first applied and then the temperature is increased. The molten metal then reaches a sufficiently high temperature that it penetrates into the gaps between the diamond particles. Therefore, when pressure is applied, when diamond particles are caught and a so-called crosslinking phenomenon occurs, this gap becomes larger, and a large metal phase is formed in this area. This large metal phase causes the welding and seizure phenomenon, thereby degrading the performance of the entire firing body as described above. The object of the present invention is to reduce the occurrence of such accumulations, and further to reduce the amount of metal contained by reducing the gaps between diamond particles.

That is, it was devised to prevent crosslinking from occurring or to destroy crosslinking once formed. There are two possible ways to do this: One method is to perform this in the absence of molten metal, and the other is to perform this in the presence of a molten metal serving as a bonding material. The former method involves graphitizing the surface of diamond powder and utilizing the low strength and lubricity of the graphite formed on the surface to prevent crosslinking. There is a method in which the powder is graphitized in advance under normal pressure or reduced pressure, and a method in which the powder is graphitized by exposing it to diamond unstable regions during hot pressing as shown in FIG. 1 a, b, c, d, and e. In the latter method, when hot pressing, for example, Fig. 1 a, b', c
As shown in 'e', the metal serving as the binder is melted under high pressure in the diamond unstable region for one day, and it is brought into contact with the diamond powder, and a part of the diamond powder is dissolved into the metal to form a bridge between the diamond powders. It can be destroyed by oxidation or graphitization. In any case, the final step of hot pressing is carried out in the diamond stable region, so the graphitized portion returns to diamond. In FIG. 1, the area (■) above the Berman-Simon line (■) indicates the diamond stable region, and the area below (@) indicates the diamond unstable region.

(2) is a Ni-C eutectic line. The diamond sintered body produced by the method of the present invention has less binding material and an increased diamond content, resulting in improved strength and heat resistance.

Therefore, the sintered diamond produced by the manufacturing method of the present invention can be used not only for wire drawing dies, but also for cutting non-metals, ceramic hard plastics, drill bits, dressers, etc., and exhibits excellent performance. Examples will be described below.

Example 1 A nickel container was filled with 40/60 mesh diamond powder and hot pressed.

The thickness of the nickel container was made sufficiently thick so that even if some of the nickel in the container penetrated into the diamond powder space, there was no problem. This container was hot pressed using an ultra-high pressure and high temperature device used for diamond synthesis. First, increase the pressure to 40kb.
After heating to 1400 qo and holding for 5 minutes. This is the diamond unstable region. After this, increase the temperature to 14
While holding the temperature at 00:00, the pressure was slowly raised to 5 bulbs B and held for 10 minutes, and after the temperature was lowered, the pressure was further lowered. The obtained sintered body contained the necessary minimum amount of Ni as a binder, and even when the fractured surface was polished, no so-called metal pools were observed. The specific gravity of the obtained sintered body was 3.70, and the amount of bonded metal was only 3.70. & capacity%. When the route shown in Figure 1 a, b'', and e was taken instead of using the method of this example, the specific gravity of the obtained brick was 4.05, and the amount of metal was also large (10.4% by volume). Also, many metal pools were recognized.

Example 2 Diamond powder of the same particle size was filled in a container with the same configuration as in Example 1 and hot pressed using the same ultra-high pressure and high temperature equipment used for diamond synthesis.

First, increase the pressure to 40kb and then increase the temperature to 125,000.
It was heated and held for 10 minutes. Thereafter, the pressure was slowly increased to 5 bulbs b, and the temperature was further increased to 140,000 and held for 10 minutes, then the temperature and pressure were lowered, and a sample was taken out. The specific gravity of the obtained Diamond Akatsuki compact was 3.82. Calculating from the specific gravity, this means that 6.0% by volume of metallic Ni is present in the Akatsuki compact.
This includes: Furthermore, when the surface was polished and observed under a microscope, almost no metal loops were observed. Example
3. Diamond powder with a grain size of 100/200 mesh was filled into a bronze container, the top of which was sealed with an embossed iron powder, and a small piece of copper was placed on top of the container.

The whole was heated to 110,000 ℃ under a vacuum of Hg on the 10-4 side, degassed, and at the same time sealed tightly. This container was hot pressed using the same ultra-high pressure and high temperature apparatus as in Example 1. First, the pressure was increased to 40 kb and then heated to 135,000. At this time, molten metal consisting of copper and iron penetrates between the diamond powders. This was then boosted to 55 kb and held for 10 minutes. When the sample was taken out at a lower temperature and pressure, a dense aggregate with a specific gravity of 3.75 and a low metal content was obtained. Example 4 Diamond particles with a particle size of 20-30 and diamond particles with a particle size of 1-10 were mixed at a ratio of 2:1.

This mixed powder was heated at 150,000 for 1 hour under a vacuum of 10-4 Hg to graphitize the surface of the diamond particles, and then filled into a container made of WC-15% Co.
It was capped with %Co. This container is placed in an ultra-high pressure and high temperature device,
After holding at 55kb140000 for 10 minutes, the pressure was lowered and the sample was taken out. The obtained diamond aggregate had no metal accumulation, diamond particles were strongly bonded to each other, and contained 6.1% by volume of an alloy having a WC-Co eutectic composition as a bonding phase. This sintered body was processed to create a cutting tool for cutting the alumina ceramic at a cutting speed of 50 m/min, depth of cut of 1, and feed of 0.
1 leg/rotating wet machine to cut 2 pieces. For comparison, a commercially available sintered diamond cutting tool was also created to cut alumina ceramic. As a result, the brazed diamond produced by the method of the present invention had flank wear of 0.1 skin, while that of the comparative product was on the 0.31 side. Example 5
After graphitizing diamond particles with a particle size of 2 to 8 French at 160,000 for 1 hour under a vacuum of 10-4 skin Hg (Mow
) The mixture was filled into a container made of C-Co-Ni and subjected to ultra-high pressure competition under the same conditions as in Example 4.

When the sample was taken out and its structure was observed, no metal pools were observed, and diamonds were bonded uniformly over the entire surface. In addition, 65% (Mow)C-Co is contained in the sintered body.
When this bran containing an alloy with a -Ni eutectic composition was processed to create a wire drawing die and a copper wire was drawn, the life was three times longer than that of a commercially available fired diamond die. Example
6 After graphitizing diamond particles with a particle size of 10 diamonds or less under the same conditions as in Example 4, a container made of TIC-M was filled with the graphitized diamond powder and 53kb14000
Sintering was carried out in an ultra-high pressure and high temperature apparatus at 0 for 10 minutes.

The obtained sintered diamond contained 7.1% by volume of TIC-
It contained an alloy with a Ni eutectic composition, and the diamond particles were bonded to each other. This competitive diamond was processed into a cutting tool, and A-25% Si was cut for 1 hour at a cutting speed of 300 m/min, a depth of cut of 0.2 skin, and a feed rate of 0.025 ribs/rotation. For comparison, a commercially available sintered diamond cutting tool was also created and tested. As a result, while the flank wear of the product of the present invention was 0.03 mm,
That of the comparative material was 0.08 m. Example 7 Diamond particles with particle size of 100 and 120 Buddha, particle size of 40
-60 French diamond particles, particle size 10-20 mountain diamond particles, particle size 2-61 diamond particles 60
:25:10:5 ratio, mixed at 1500o
Graphitization was carried out under a vacuum of 10-4 Hg for 3 minutes at 10°C.

Fill a WC-Co container with this powder and place Co on top of it.
Place the plate and heat it to 56kb, 1450qC using an ultra-high pressure and high temperature equipment.
It was sintered for 15 minutes. When the sample was taken out and the sintered diamond was observed, it was found that it had a dense structure in which diamond particles were bonded to each other. This sintered body was used to cut karanite at a cutting speed of 200/min, a cutting depth of 1 willow, and a feed rate of 0.2 side/times in a wet manner. For comparison, we also tested a commercially available diamond compact for bits. As a result, the flank wear of the sintered body of the present invention after 5 minutes of cutting was on the 0.15 side, while that of the comparative material was on the 0.6 side. Example 8 Diamond particles with a particle size of 5 or less are 155,000
Graphitization was carried out in a vacuum of 10-4 hours Hg.

After mixing these diamond particles and diamond particles with a particle size of 15 French or less in a volume ratio of 1:1, this powder was filled into a Mo cylinder and a WC-Co container, and placed in an ultra-high pressure and high temperature equipment. , 145,000 for 15 minutes. When the sintered body was taken out and its structure was observed, it was found to be very delicate. This compact was processed to create a cutting tool, and a resin containing hard particles was applied at a cutting speed of 20 skin/min.
Machining was performed for 2 minutes with a cut depth of 0.5 skin and a feed rate of 0.1 skin/rotation. For comparison, a commercially available diamond cutting tool with a similar particle size was prepared and tested. As a result, the flank wear of the product of the present invention was 0.2 sail, while that of the comparative product was 0.35.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing diamond stability, unstable regions, and hot pressing conditions. The vertical axis shows pressure (kb) and the mechanical axis shows temperature (°C). O diagram

Claims (1)

[Claims] 1. After graphitizing the surface of the diamond powder at a diamond unstable pressure and temperature range, the diamond powder and the bonding metal are brought into contact with each other, and the diamond powder and the bonding metal are brought into contact with each other within the diamond stable pressure and temperature range. A method for producing a diamond sintered body characterized by sintering. 2 Diamond sintering, characterized by sintering the diamond powder and the bonding metal within the stable diamond pressure and temperature range, in which diamond powder is graphitized by contacting it with a bonding metal melted under high pressure in a diamond unstable pressure and temperature range. Method of manufacturing solids.