JPH0672048B2 - Method for producing zirconium oxide-based composite sintered body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a zirconium oxide-based composite sintered body used as a cemented carbide tool or a high temperature structural material.

2. Description of the Related Art Conventionally, in a zirconium oxide-carbide composite sintered body, a carbide powder and a zirconium oxide powder synthesized by first mixing carbon powder or solid carbon with a metal or an oxide thereof and reacting at a high temperature are sufficiently mixed. After that, it was manufactured by sintering under high temperature and high pressure.

Problems to be Solved by the Invention Since the manufacturing process of this method is long and complicated, impurities are easily mixed in, and energy consumption is very large.

Means for Solving the Problems A feature of the present invention is that pressure is applied to a compact of a mixture of zirconium metal powder (which becomes zirconium oxide after the reaction), an oxide (which becomes carbide after the reaction), and carbon. In this state, a part of the molded body is ignited by a strong ignition to cause a combustion reaction, and the chemical reaction synthesizes particles of carbide and zirconium oxide, and the reaction heat sinters these particles to produce zirconium oxide- The purpose is to obtain a carbide composite sintered body.

Effects According to the present invention, a high-density zirconium oxide-carbide composite sintered body can be easily obtained only by igniting the molded body under pressure. Therefore, compared with the conventional method for producing a sintered body prepared by using powders of carbide and zirconium oxide, energy saving is extremely high, and the obtained sintered body also has an extremely high purity. Further, according to the manufacturing method of the present invention, a composite sintered body of carbide and zirconium oxide, which was difficult by the conventional manufacturing method, can be manufactured very easily.

Examples Example 1 As starting materials, zirconium powder having a particle size of 10 μm or less, titanium dioxide (TiO ₂ ) powder having an average particle size of 1 μm, and carbon black using acetylene as a raw material were used.
After mixing at a molar ratio of 1: 0.9, it was press-molded into a column having a diameter of 10 mm and a height of 10 mm. The compact was sintered using a uniaxial pressure vacuum hot press using a silicon carbide mold material. Ignition of the molded body was performed by energizing the tungsten filament. The sample was heated at room temperature in a vacuum (1 mmHg) atmosphere under a pressure of 0.1 GPa to energize the ignition heater to start the reaction. When the obtained sintered body was identified by X-ray diffraction, only diffraction lines of titanium carbide, tetragonal zirconium oxide and monoclinic zirconium were found. From this X-ray diffraction, it was found that tetragonal zirconium oxide and monoclinic zirconium were contained at a ratio of about 1: 1. The density of this sintered body was 5.25 g / cm ³ .

The chemical reaction equation of this process is as follows.

Zr + TiO ₂ + C → ZrO ₂ + TiC As can be seen from this chemical reaction formula, this reaction is based on the reduction of TiO ₂ by Zr metal, and the reduced Ti metal (it seems to be melted into a liquid) Reacts with C
It becomes TiC. Since the reaction heat at this time is large, the sample will reach a high temperature (up to about 2000 ° C) without being heated from the outside, and since it is pressurized, ZrO ₂ particles and TiC
The particles are sintered to obtain a ZrO ₂ -TiC composite sintered body.

Generally, tetragonal zirconium oxide, which is unstable in a pure state, exists stably in the sintered body even at room temperature, which is a major feature of the zirconium oxide-based composite sintered body produced by this sintering process.

Example 2 Zirconium powder having a particle size of 10 μm or less as a starting material, calcined amorphous silica dioxide (Carplex manufactured by Shionogi Pharmaceutical Co., Ltd.)
CS-5) Using carbon black made from acetylene as a raw material, mixing them at a molar ratio of 1: 1: 1, and then cultivating Example 1
It was processed in the same process as. However, in this embodiment, 300
The reaction was started by heating to ° C. The obtained sintered body is X
As a result of identification using line diffraction, only diffraction lines of β-type silicon carbide, tetragonal zirconium oxide and monoclinic zirconium were found. From this X-ray diffraction, it was found that tetragonal zirconium oxide and monoclinic zirconium were contained at a ratio of about 1: 1. The density of this sintered body is 4.72
It was g / cm ³ .

Example 3 As a starting material, zirconium powder having a particle size of 325 mesh or less, niobium pentoxide (Nb ₂ O ₅ ) having an average particle size of 1 μm, and carbon black using acetylene as a raw material were used. 0.5 μm zirconium oxide powder was added, they were mixed in a molar ratio of 2: 5: 4: 0.2 and then treated in the same manner as in Example 1. When the obtained sintered body was identified by X-ray diffraction, only diffraction lines of niobium carbide, tetragonal zirconium oxide and monoclinic zirconium were found. From this X-ray diffraction, it was found that tetragonal zirconium oxide and monoclinic zirconium were contained at a ratio of about 6: 4. The density of this sintered body is 6.33 g / cm
^{Was 3} .

Example 4 Zirconium powder having a particle size of 1000 mesh or less, tantalum pentoxide (Ta ₂ O ₅ ) having an average particle size of 1 μm, and carbon black using acetylene as a raw material were used as starting materials, and they were used in a molar ratio of 2: 5: 4. After mixing in, the same process as in Example 1 was carried out. When the obtained sintered body was identified by X-ray diffraction, only diffraction lines of tantalum carbide, tetragonal zirconium oxide and monoclinic zirconium oxide were found.
The density of this sintered body was 9.60 g / cm ³ .

Example 5 Zirconium powder having a particle size of 10 μm or less, tungsten trioxide (WO ₃ ) having an average particle size of 3 μm, and carbon black using acetylene as a raw material were used as starting materials.
After mixing at a molar ratio of 1: 1, the same process as in Example 1 was carried out. When the obtained sintered body was identified by X-ray diffraction, only diffraction lines of α-type tungsten carbide, tetragonal zirconium oxide and monoclinic zirconium were found. The density of this sintered body was 9.72 g / cm ³ .

EFFECTS OF THE INVENTION According to the production method of the present invention, in a state where pressure is applied to a molded body of a mixture of zirconium powder, an oxide and carbon, only a part of the molded body is ignited to cause a combustion reaction. Thus, a zirconium oxide-carbide composite sintered body can be produced. Therefore, according to the production method of the present invention, a zirconium oxide-carbide composite sintered body can be obtained at a much lower temperature process as compared with the conventional production method using the carbide powder and the oxide powder, that is, with a very small energy. Can be made. Moreover, the obtained sintered body has the same characteristics as the sintered body produced by the conventional manufacturing method.
Further, the production method of the present invention has a feature that zirconium oxide can be stabilized without solid solution of calcium oxide or yttrium oxide.

Claims (5)

[Claims] 1. A compact formed of zirconium powder, oxide powder and carbon is ignited under pressure to a part of the compact to initiate a combustion process, and thereafter zirconium powder, oxide powder and A method for producing a zirconium oxide-based composite sintered body, wherein the reaction with carbon and the sintering of the generated zirconium oxide and carbide proceed by the heat generated as a result of the combustion process. 2. The method according to claim 1, characterized in that, under the conditions of pressurization and heating, a compact made of zirconium powder, oxide powder and carbon is ignited to start a combustion process. A method for producing a zirconium oxide-based composite sintered body. 3. The method for producing a zirconium oxide-based composite sintered body according to claim 1, wherein the oxide powder is an oxide of any one of elements of Groups 4, 5b and 6b of the periodic table. . 4. A molded body made of zirconium powder, oxide powder, carbon, and oxide powder not participating in the reaction is ignited on a part of the molded body to start a combustion process, Subsequent reaction of zirconium powder and oxide powder and carbon and sintering of the produced zirconium oxide and carbide and the oxide not involved in the reaction are promoted by the heat generated as a result of the combustion process. Production method. 5. The method for producing a zirconium oxide-based composite sintered body according to claim 4, wherein the oxide powder not involved in the reaction is zirconium oxide.