JPS6126574A - Superhard sintered body having sandwich structure - 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 (1) Technical field: Sintered diamond (PCD) and sintered high-pressure phase boron nitride (PCBN) are used as long-life tools or as tools for cutting and cutting, especially the latter. It has rapidly become popular in recent years as an indispensable item for various purposes.

However, there are some fields in which it has not become popular due to the lack of materials with suitable shapes. For example, there is a huge demand for tools for ana-mei for the purposes listed in 1. However, because there were no materials suitable for making ana-mei tools, it has not been put into practical use until now. be.

The object of the present invention is to provide a material which is particularly suitable for drilling tools.

(2) Technical background The PCD and PCBN tool materials currently on the market are those with a two-layer structure of cemented carbide and PCD, or those with a single structure of only PCD. .

If it is a single piece structure, it can be used as is as an indexable tool. Those that have a two-layer structure with cemented carbide are used to be processed into tools with more complex shapes. PCD and PCBN are not brazable, but
Since the cemented carbide layer can be brazed, it has the advantage that tools with complex shapes can be easily formed.

When drilling holes in tools, it is desirable to braze them on both sides in order to maintain their holding strength. With single-sided brazing, the brazed area is large (sometimes it cannot be removed) and the holding strength is not sufficient.

This is the reason why until now not a single PCD and PCBN hole puncher has appeared on the market. Of course, there are many cases where drilling is required in addition to tools, and it goes without saying that the present invention is not limited to tools.

(3) Disclosure of the Invention If double-sided brazing is desired, a structure in which PCD or PCBN is sandwiched with cemented carbide is first required.

Conceivable. The present inventors also first attempted to produce a prototype of this structural material. The conclusion obtained was that it was almost impossible to produce it industrially due to the occurrence of many cracks. When we investigated the reason for this, we found that although cemented carbide is a material with a small coefficient of thermal expansion, it still
It was concluded that this is due to the difference in thermal expansion coefficient with N. It is thought that there is no stress during sintering, and stress is generated during cooling due to the difference in the coefficients of thermal expansion of the two components.

The coefficient of thermal expansion of each material with a low coefficient of thermal expansion and a high melting point is as follows.

Sintered diamond 5.26 Cemented carbide and Mo have the smallest difference in thermal expansion coefficient from diamond.

Cooling after sintering is usually done while applying high pressure, so that materials that are difficult to deform are cooled in a state that makes them even more difficult to deform. If the deformation stops at 200℃ this summer, P
The distortion generated on the CD is (5,7-5,2[i)X 10''X 1200=
It becomes 5.28X 10-.

Young's modulus of sintered diamond is 9.49X 10'k
g/square, the stress generated is 50 kg/■-. On the other hand, the stress generated on the cemented carbide side is 30 kg because its Young's modulus is 5.7X 10' kg/++♂
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If a sandwich structure is made of cemented carbide, the sintered diamond will crack as described above, making industrial production impossible. This means that sintered diamond cannot withstand a stress of 50 kg/ms'.

Therefore, the present inventors previously proposed using Mo, W, or an alloy thereof, which has greater plastic deformation than cemented carbide, for one side of the sandwich. This gives an appearance
We succeeded in obtaining a sintered body with a sand winch structure without any cracks. However, when attempting to make tools from this sintered body by wire-cutting small pieces of the required shape, cracks often appeared, making it difficult to manufacture tools stably.

Therefore, the present inventors came up with the idea of using a softer metal, which had been hesitant to use because of its large coefficient of thermal expansion. For example, the coefficient of thermal expansion of CO is 12.5XlO-', which is more than twice that of cemented carbide.

However, if plastic deformation occurs easily during cooling, the stress generated in the sintered diamond layer should be reduced as a result.

In the case of CO, assuming that no plastic deformation occurs, the amount of strain is (12,5-5,2G)X If''XI200== using the same calculation as before.
8. [The stress occurring in the i9X 10-3 sintered diamond layer is 8.69 IX 10' = 182k
g/dragon 3, which is significantly higher. This is the reason why metals with high thermal expansion coefficients such as Go are discouraged.

Another reason is that since the melting point is not high enough, it may melt and move during sintering or be excessively deformed, making it impossible to obtain a sintered body with a sandwich structure in the correct shape.

Despite the above-mentioned concerns, the inventors attempted to make a prototype using a metal such as Co.

As a result, a diamond sintered body with an unexpectedly good sandwich structure was obtained. This fact indicates that metals such as Co have sufficient plastic deformability.

Even if 90% of the strain currently generated is released by plastic deformation, a stress of 824X (+ - o, a) = 82.4 kg/- remains, which is higher than in the case of the cemented carbide described above. At least the stress of the sintered diamond layer must be at a stress level of 50 kg/- or less. That is, (824-5
0)/824: 93.9% of the stress must be released at 0.939. This means that at least 93.9% of the stress of 182 kg/- generated in CoH must be released.
That is, 171 kg/wm' means that it must be released by plastic deformation.

Therefore +82X (1-” 0.939) = l1kg/open2
This means that the 00 layer is plastically deformed below the stress of . For example, the tensile yield point of SIOc (structural carbon steel containing 0.08-0.13% carbon) at room temperature is 21k.
It is displayed as g/mm1 or more. At high temperatures this value becomes significantly lower F. Therefore, it can be considered that it is very easy for CO to undergo plastic deformation under 11 kg/- at a high temperature of about 500°C. This is why Co is used for sun drying, which has a large difference in thermal expansion coefficient from sintered diamond.

This is the reason why a structure with a 1-h structure was easily obtained.

As can be seen from the above explanation, it does not need to be a material that easily plastically deforms at high temperatures, and C09N++ Fe
l Cu+ Ag+ AQ+ Various materials such as Zn and alloys thereof can be mentioned. However, since this material usually comes into direct contact with the sintered diamond, it is desirable that the material does not harm the properties of the diamond when it comes into direct contact. Furthermore, due to the manufacturing method described in Examples, it is preferable to use the same material as the binding material of the sintered diamond. Particularly preferred from this point of view are C09Ni, Fe, and alloys thereof. Particularly preferred are Co part Nr and alloys thereof.

Among these, Fe may react with diamond and generate Fe5C, so in the case of PCBH, metal is rarely used as a binder, so metal generally does not react with the sintered body during sintering. It is necessary. For this reason,
Brazing is often performed by placing an inert material such as Ta between the metal and the sintered body. Inert metals can be very thin. As the metal for brazing, a metal that is particularly easily plastically deformed and can be brazed is used.

That is, COr N i + F el CuI AQ
etc.

From the point of view of releasing the stress generated during cooling, it is acceptable to have metal such as Go on only one side. In this case, if there is WC-Co on the other side, for example, the amount of plastic deformation on that side is very small, causing distortion due to the difference in thermal expansion coefficients, resulting in slight warping of the whole. In this sense, Go on both sides
It is preferable to use metals such as However, there are drawbacks such as difficulty in maintaining the shape using only CO when manufacturing a sintered body, and the tendency for the Co part to wear out when used as a tool. Therefore,.

-Whether only the outer layer is made of a metal that easily deforms plastically or whether both sides are made is determined by its method of manufacture and use.

The amount of plastic deformation that needs to be adjusted is +L of Go mentioned in +iq.
n was done. As the temperature of soft metals such as Co + N itF el Cu increases, the yield point thereof decreases rapidly. Therefore, it can be considered that it deforms into a container with low stress during cooling.

Example 1 Diamond powder with a particle size of 5 microns was placed between a cemented carbide plate of WC-5% Co composition with a diameter of I3w++ and a thickness of IIIN and a Co plate with a diameter of 13mm and a thickness of 0.5mm, using an ultra-high pressure and high temperature device. When the diamond was sintered under conditions of 50,000 atm % and 1400 degrees, a crack-free diamond sintered body with a thickness of 0.5 mm was obtained. When cemented carbide was used instead of Co, cracks were observed in the diamond sintered body.

When the whole was cut lengthwise and the microstructure was examined, it was found that there was no difference between the entire cemented carbide part and the diamond part compared to when a sintered body made of two layers of ordinary diamond and cemented carbide was made.

That is, during sintering, a liquid phase mainly composed of Co entered the diamond portion and sintered the diamond powder. In the Co part, carburization was observed on the side in contact with diamond.

Example 2 A grain size of 2 was placed between two Co plates with a diameter of 131 and a thickness of 0.5 mm.
．． Diamond powder with a thickness of 5 μm was placed and sintered using an ultra-high pressure and high temperature device under conditions of 50,000 atm and 400°C.

A sandwich-structured sintered body with CO attached to both sides without cracks was obtained.

Example 3 Similar to Example 1 in which a Ni plate was used instead of Go in Example 2, a sintered body with a good sandwich structure without cracks was obtained.

Example 4 A mixed powder of 60% GBN and 40% TiN was placed on a WC-7% CO cemented carbide plate with a diameter of 13 mm and a thickness of 1 mm, and a Cu plate of 1 mm thick was placed on top of this. there was.

Using an ultra-high pressure and high temperature device, this structure was manufactured at 40,000 atmospheres +
Sintering was performed at 350'C.

A CBN sintered body with a good sand winch shape without cracks was obtained.

Manufacturable or manufactured by the present invention 7. (Tools that facilitate this include the twist drill shown in Fig. 1, the glass cutting tool shown in Fig. 2, and the roll shown in Fig. 3).

[Brief explanation of the drawing]

FIG. 1 shows an example in which the tool material obtained by the present invention is used in a twist drill, where (6L) is a side view and (b) is a front view. Figure 2 shows a glass cutting tool obtained using the accumulated moon obtained in this application, (^) is a side view, (b)
is a front view. FIG. 3 also shows an example of a roll using the material obtained in the present application, with (4) being a side view and (b) being a front view. 1: Sintered diamond or sintered high pressure phase boron nitride 2
: Ultra-hard alloy or soft metal 3: Soft metal Procedural Amendment Department 1982 Patent Application No. 148475 2 Title of invention Cemented carbide W sintered body with sandwich structure 3 Related Patent Application Personnel Location
5-15 Kitahama, Higashi-ku, Osaka Name (2+3)
) President of Sumitomo Electric Industries, Ltd. Yohi Tetsubu 4, Agent address: 5, Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka City, Date of amendment voluntary amendment 6, Subject of amendment Mei NiE Buttocks 7 of the Detailed Description of the Invention, Contents of the Amendment (1) In the specification, page 8, line 4, ``Even if it is not a material'' is corrected to ``Any material.''

Claims (4)

[Claims] (1) Ultra-hard sintered material with a sandwich structure characterized by having a metal or alloy bonded to at least one side thereof that can absorb stress caused by the difference in coefficient of thermal expansion with sintered diamond or sintered CBN through plastic deformation. Concretion. (2) The ultra-hard sintered body having a sandwich structure according to claim (1), wherein the metal or alloy is an iron group metal or an alloy thereof. (3) The ultra-hard sintered body having a sandwich structure according to claim (2), wherein the iron group metal or its alloy is Co or a Co alloy. (4) The ultra-hard sintered body having a sandwich structure according to claim (1), wherein the metal or alloy is copper or a copper alloy.