JPS597669B2 - Metal boride-zirconium oxide ceramic materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel high-strength, high-hardness metal boride zirconium monoxide ceramic material.

In general, metal boride ceramics have a high melting point, high hardness, and excellent high-temperature strength, so they have traditionally been used as materials for cutting tools and heat engine parts, and recently as materials for rockets that require heat resistance. Attention has been paid.

However, ceramics formed only from metal borides have the serious drawbacks of low flexural strength and brittleness.

The present inventors have conducted extensive research to overcome these drawbacks of metal boride ceramics, and have developed a high-strength, high-hardness ceramic made by first sintering a powder mixture of metal boride and zirconium oxide. The material was proposed (Japanese Patent Application No. 151596/1983).

However, in recent years, technological progress has been remarkable in various industrial fields, and the demand for improved properties of various materials is increasing, and ceramics are no exception.

Therefore, the present inventors conducted further research to further improve the properties of metal boride zirconium monoxide ceramics, and found that by adding a small amount of cubic metal carbide, the strength and hardness were further improved. We have discovered that the scales are high, and based on this knowledge, we have accomplished the present invention.

That is, the present invention provides titanium diboride powder or a powder mixture of titanium diboride and other metal borides, and
Provided is a metal boride zirconium monoxide ceramic material obtained by sintering a mixture of 0 to 80% by weight of zirconium oxide powder as a basic component and 0.001 to 10% by weight of cubic metal carbide powder added thereto. It is something to do.

In the present invention, a powder mixture of titanium diboride and other metal borides can be used instead of titanium diboride powder, but the metal borides include TaB2,
NbB2, vB2, zrB2, CrB2, MoB2, M
MB2 type metal borides such as nB2, W2B5, MO
Metal borides that become MB2 type when sintered at high temperatures such as 2B5, and TaB, NbB, VB, ZrB, CrB, Mo
MB type metal borides such as B, MnB, and WB, which may be used alone or in combination of two or more.

In combination use, the same type may be used together,
Also, different types may be used together.

These metal borides are preferably pulverized in advance before being mixed with other components, and those having an average particle size of 5 μm or less can be advantageously used.

Furthermore, the zirconium oxide used in the material of the present invention is
ZrO2, ZrO, ZrOO, 35 and Zr30
1-x may be used, and metallic zirconium may be used under conditions where it can change to zirconium oxide after sintering.

However, preference is given to zirconium dioxide, ZrO2.

Zr02 has various crystal systems, ie, monoclinic system, tetragonal system, and cubic system, and in the present invention, any crystal system can be used.

When cubic system ZrO2 is used, Y203, MgO or CaO, which is known as a thermal stabilizer, is usually used.
Can be used in small amounts with.

These zirconium oxides may be used as a single component or in combination of two or more types.

Moreover, those of different crystal systems can also be used together.

When mixed with other components, these zirconium oxides are finely pulverized in advance and have an average particle size of 5 μm or less, preferably 1 μm.
Prepared to be less than μ.

The metal boride and zirconium oxide, which are the basic components of the material of the present invention, are not completely contained in the range of the amount of the carbide added as the third component when considering the physical properties of the sintered body finally obtained. It is necessary to use a proportion of zirconium oxide in the composition material such that the amount ranges from 10 to 80% by weight.

If the amount exceeds this range, sufficient mechanical strength cannot be obtained, which is not preferable.

The cubic carbides added as the third component of the material of the present invention include TiC, ZrC, HfC, VC, NbC,
Metal carbides having a cubic crystal structure such as TaC, which may be added when mixed with the basic component powder, or may be formed during sintering. good.

In that case, for example, a combination of carbon and metal powders may be added.

When added to the basic components, it is desirable that the carbide or carbon and metal be ground as finely as possible, for example, to a particle size of 5 μm or less, particularly preferably 1 μm or less.

This carbide is 0.001 to 10% based on the total weight of the material.
It is necessary to add it within a range of % by weight.

Q. If the amount is less than 0.04% by weight or more than 10% by weight, no significant increase in mechanical strength and hardness will be obtained.

The raw material mixture in the present invention can be prepared by uniformly mixing the basic components and the fine powder of carbide, but for the purpose of mixing, the raw material mixture may be further pulverized using a pulverizer.

The ceramic material of the present invention can be produced by filling a raw material mixture into a mold such as a graphite mold, and
In a neutral, reducing or oxidizing atmosphere such as carbon dioxide gas or air, for example, 50 to 300 kg/
1 at a high temperature of 1600-2500°C under crrt pressure.
It can be obtained by heating and sintering for 0 to 200 minutes.

In addition, commonly known ordinary sintering method or H, I. Sintering can also be performed using the P method or the like.

The material of the present invention has particularly high strength, hardness, and good structure, and also has excellent oxidation resistance and heat resistance, and is a dense sintered body, so it is extremely useful as a cutting tool material, heat-resistant material, or wear-resistant material. It is suitable and can be used in a wide range of fields.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example I 67.4% by weight of TiB2 powder and 21% by weight of NbB2 powder
and 30% by weight of monoclinic ZrO2 powder and 0.5% of TiC powder.
% by weight, this mixed powder was filled into a graphite mold, and heated at 2000° C. for 30 minutes while pressurizing to 200 kg/crA in vacuum.

The sintered body thus obtained has a transverse rupture strength of 140 kg/v.
It had a Bitkers hardness of 2500 kg/1.

When the structure of this sintered body was observed with a scanning electron microscope, no pores were found within the structure.

Although this sintered body was heated in air, it was not oxidized up to 1000°C, but was slightly covered with an oxide film at 1200°C.

Example 2 One or more metal borides, monoclinic zirconium oxide, and carbide fine powder in various proportions shown in Table 1 were thoroughly mixed,
Each sintered body was manufactured by hot-pressing this mixed powder for 30 minutes or by cold-forming this mixed powder and then normal sintering for 2 hours under predetermined conditions.

Table 1 shows the composition of the sample thus obtained, the sintering conditions, and the composition of the sintered body after sintering.

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Claims (1)

[Claims] 1. Titanium diboride powder or a powder mixture of titanium diboride and other metal borides, and 10 to 80% by weight based on the total amount.
The basic component is zirconium oxide powder, and Tic
, ZrC, HfC, VC, NbC1TaC cubic metal carbide powder o. A metal boride zirconium monoxide ceramic material obtained by sintering a mixture to which ooi to 1o wt% is added. 2. The ceramic material according to claim 1, wherein the other metal boride is at least one metal boride selected from tantalum, niobium, vanadium, silconium, chromium, molybdenum, manganese, and tungsten. .