JPH0336780B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a novel high-strength heat-resistant ceramic material that can be used as a high-strength structural material that exhibits physical properties similar to those at room temperature even at high temperatures. (Prior art) Carbides, nitrides, etc. of transition metals from groups of the periodic table.
It is well known that borides and silicides are suitable as high-strength structural materials because they generally have high melting points and excellent hardness and other mechanical properties. Among these, carbides and nitrides have high hardness, and have traditionally been used in cutting tool materials and the like by taking advantage of their high hardness, as typified by cemented carbide. In contrast, borides have not been widely used so far. Furthermore, there are only a few examples of silicides being put to practical use as resistance heating elements. Although carbonitrides have good sinterability, their grains grow significantly and form a coarse structure, so their simple sintered bodies have low strength. In addition, borides have extremely poor sinterability when used alone, and require high temperature and pressure to sinter. The titanium carbonitride-metal boride compound system (Japanese Patent Publication No. 59-18349) proposed by the present inventors suppresses the grain growth of titanium carbonitride by combining carbonitride and boride, and It is a high-density and high-strength ceramic material with improved sinterability of boride. However, this ceramic material requires heating at high temperatures to manufacture it, and
Oxidation resistance at high temperatures is insufficient. On the other hand, although silicides are known to have good sinterability and oxidation resistance, they have the disadvantage that their simple sintered bodies are extremely brittle at room temperature. (Problems to be Solved by the Invention) The present invention overcomes the drawbacks of conventional carbonitride-boride-based sintered bodies and silicide-based sintered bodies, and has the same superiority at high temperatures as at room temperature. The purpose of this work was to provide a new ceramic material useful as a heat-resistant, high-strength structural material that exhibits excellent mechanical properties. (Means for Solving the Problems) As a result of various studies on high-strength heat-resistant ceramic materials, the present inventors found that a system that combines a carbonitride-boride system with a silicide system has the advantages of each. The present inventors have discovered that they exhibit excellent characteristics that compensate for the shortcomings of each, and have accomplished the present invention based on this knowledge. That is, the present invention provides (A) Ti, Zr, Hf, V, Nb,
20 to 90% by weight of powder of at least one metal compound selected from carbonitrides and borides of Ta, Cr, Mo or W; (B) Ti, Zr, Hf, V, Nb,
The present invention provides a high-strength, heat-resistant ceramic material comprising a sintered body of a mixture of 80 to 10% by weight of powder of at least one metal compound selected from silicides of Ta, Cr, or W. In the carbonitride component (A) of the ceramic material of the present invention, carbide and nitride are not used individually, but are used as a solid solution in the raw material stage. This carbonitride is expressed as M(CαNβ), where M is a metal, and has superior mechanical properties compared to carbides and nitrides due to the solid solution effect. The atomic ratio α:β is preferably 10:90 to 90:10. In addition, in order to improve sinterability and refine the structure of the sintered body, components (A) and (B) have an average particle size of 2 μm.
It is preferable to use it as a powder with a particle size of m or less. The mixing ratio of component (A) and component (B) is 20 to 90% by weight of component (A) and 80 to 10% by weight of component (B), preferably 40 to 80% of component (A), based on the total weight of the mixed powder. Weight%, component (B) 60
Selected within the range of ~20% by weight. Outside this range, the sinterability deteriorates and the strength significantly decreases. Particularly in the case of carbonitrides, if the carbonitride content increases, the structure of the sintered body tends to become coarse, so it is desirable to keep the content to 60% by weight or less. On the other hand, in the case of boride, if the content is too large, the sinterability deteriorates and voids remain. Also, in the case of silicides,
If this amount increases too much, the hardness decreases and the material becomes brittle. The mixed powder of components (A) and (B) is easily sinterable, and can be easily sintered by a normal hot pressing method or ordinary sintering method to form a desired ceramic material. (Effect of the invention) The ceramic material of the invention has a high melting point,
Furthermore, it has properties that are extremely suitable as a high-temperature structural material, such as high strength, high hardness, and high toughness at high temperatures as well as at room temperature. Moreover, since it is easy to sinter, it is easy to manufacture. Moreover, when the carbonitride content is small, it also has the advantage of having oxidation resistance. In this way, it is a material with extremely excellent properties, and is used as a structural material, wear-resistant material, cutting tool material, etc.
It can be used in many fields that require heat resistance, high strength, high hardness, etc. (Example) Next, the present invention will be explained in more detail with reference to Examples. Example 1 40 parts by weight of Ti(C ₅₀ N ₅₀ ) powder, 20 parts by weight of TiB ₂ powder, and 40 parts by weight of NbSi ₂ powder were weighed,
A mixed powder composition was prepared by uniformly mixing. Next, this mixed powder composition was filled into a graphite mold, and heated at 1600°C under uniaxial pressure of 20 MPa in a vacuum.
Pressure firing was performed for 30 minutes to produce a ceramic material. Transverse rupture strength of the obtained ceramic material
1100MN/m ² , hardness 1680Kg/mm ² , fracture toughness value
It was 4.7MN/m ^3/2 , and there was no empty space. Examples 2 to 19, Comparative Examples 1 to 10 Ceramic materials were manufactured by changing the composition of the raw material mixed powder composition and using the sintering conditions shown in the following table. The properties of the ceramic material thus obtained are shown in the table below. In addition, TiCN in the table is Ti(C ₅₀ N ₅₀ )
It is an abbreviation of

【table】

[Table] Note that when an oxidation test was conducted at 1000°C on the ceramics obtained in Example 15 in the above table, a glass phase was formed on the surface and oxidation did not proceed.

Claims (1)

[Claims] 1 (A) 20 to 90% by weight of powder of at least one metal compound selected from carbonitrides and borides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, or W;
(B) High-strength, heat-resistant material made of a sintered body of a mixture of 80 to 10% by weight of powder of at least one metal compound selected from silicides of Ti, Zr, Hf, V, Nb, Ta, Cr, or W. Ceramics materials.