JPH0553756B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention belongs to the technical field of manufacturing various material parts with high functionality by rapidly compressing powder materials, cast materials, or composite materials at high density. .

[Conventional technology]

HIP and condensation HIP are known as techniques for compressing these materials to high density. The present invention is
This is related to the improvement of the Ceracon method, which is one of the HIP methods (Reference: The International
Journal of Powder Metallurgy and Powder
Technology, July, 1985). The Ceracon method uses a normal press machine to fill a die with ceramic grains or carbon grains heated to a high temperature as a pressure medium, and then presses the material to be compressed, which is a powder compact or capsule filled body heated to a high temperature. This is a method of applying high temperature and pressure by setting the punch at the center of the pressure medium and lowering the punch.

[Problem to be solved by the invention]

In the conventional method, the pressure medium heated outside the die and the material to be compressed are set in the die, so the material to be compressed is exposed to high temperatures for a long time during heating and compression and from the end of pressing until cooling. Therefore, in order to increase the density of materials with non-equilibrium compositions such as amorphous amorphous, it is necessary to devise methods such as high-frequency heating of the material to be compressed or methods for quickly removing and cooling the material to be compressed after pressing. Must be. Also,
The heated pressure medium is in contact with the inner surface of the die, and the die becomes hot, so various measures must be taken to cool the die.

The object of the present invention is to heat, compress, and cool a material to be compressed in a short time, and further to reduce the temperature rise of a die.

[Means to solve the problem]

We have conducted various studies on means to solve the above problems, and it has become clear that the following method is optimal. That is, the material to be compressed is placed in the center of the die together with powder or granules as a pressure medium in a die installed in a press machine, a heating agent is placed around the outer periphery of the material to be compressed, and the heating agent is ignited. The material to be compressed is compressed under high temperature and pressure by lowering the rear punch. As the heating agent, for example, a thermite heating agent may be used.

In this way, the material to be compressed is heated rapidly, but if a sufficient distance is maintained between the heating agent and the inner surface of the die, the die will not be heated to a high temperature.
Further, even if the material to be compressed and the pressure medium near the heating agent are heated, the surrounding pressure medium serves as a refrigerant and the material to be compressed is rapidly cooled after being heated and compressed. That is, by such a method, the material to be compressed can be heated and compressed in a very short time, and the die is not exposed to high temperatures.

Thermite-based exothermic agents consist of metal oxide powder and metal or metalloid metal or alloy powder, and generate heat through redox reaction between the two. A typical example is a combination of iron oxide powder and aluminum powder, in which case the maximum temperature reached is 2000°C or higher. Furthermore, if a combination of iron oxide and silicon or ferrosilicon powder is used, a temperature of about 1000°C can be obtained. Since various other combinations are known, it is sufficient to use an exothermic agent that corresponds to the required temperature.

These exothermic agents can be ignited by an electric spark or the like. Therefore, if a copper wire is drawn from the top of the press container to the exothermic agent inside the pressure medium and a spark is generated near the exothermic agent using an electric circuit immediately before pressing, ignition will occur.

Incidentally, in order to facilitate ignition, an ignition agent may be applied to the surface of the exothermic agent. A suitable ignition agent is, for example, aluminum + boron with barium peroxide added as an oxidizing agent.

〔Example〕

Material to be compressed 4 was obtained by vacuum-sealing SUS304 stainless steel spherical powder with a particle size of -100 mesh into a stainless steel capsule with a diameter of 20 mm and a height of 20 mm. This was filled together with a pressure medium 5 and a heating agent 6 into a die 1 having an inner dimension of 100 mmφ and a height of 100 mm as shown in FIG. The pressure medium 5 is spherical alumina powder with an average diameter of 50 μm + 20% graphite powder. As the thermite exothermic agent, heating agent 6, a mixture of 79.2% by weight of iron oxide and 20.8% by weight of silicon was formed into a cylindrical shape by cold pressing. The dimensions of this cylindrical heating agent 6 are an outer diameter of 50 mmφ, an inner diameter of 40 mmφ, and a height of 50 mm. In order to facilitate ignition, the main ingredient is aluminum with a small amount (5 to 30%) of boron added and barium peroxide as an oxidizing agent. copper oxide,
A powder mixed with strontium peroxide was added to a part of the upper surface of the heating agent 6.

Ignition was accomplished by placing a pistol-type flint-type spark generator above the pressure medium to generate a spark near the ignition agent.

The temperature of the heating element reaches its maximum temperature of 1000℃ approximately 1 minute after ignition.
℃, and after maintaining the maximum temperature for about 2 minutes, the temperature rapidly decreased to below 500℃ after 10 minutes.

1 minute after ignition, lower the punch 2 for about 1 minute.
A pressure of 400 tons was applied.

The relative density of the compressed material 4 had reached almost 100%.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional schematic diagram showing an embodiment of the present invention. 1...Dice, 2...Upper punch for pressurization, 3...
Lower punch for knockout, 4... Material to be compressed, 5
...Pressure medium, 6...Heating agent.

[Claims]

1 zircon powder to silicon carbide short fiber 10~
A method for producing a silicon carbide fiber-reinforced zircon composite sintered body, which comprises sintering a mixture containing 70% by weight at a temperature of 1400° C. or higher and a pressure of 100 kg/cm ² or higher in a non-oxidizing atmosphere.