| 摘要 |
PURPOSE:To obtain a seal having a light weight, a sufficient strength, and resistances to corrosion, change of properties, and burning by a method wherein a second silicon carbide powder synthesized in a specific method and specified in average particle diameter is mixed in a specific ratio in a first silicon carbide powder specified in average particle diameter, and a sealing part is provided in a sintered body obtained by heating and sintering this mixture. CONSTITUTION:Material gas made of a silane compound or a silicon halide and a hydrocarbon is led into a plasma in a non-oxidizing atmosphere to be synthesized with each other by a gas phase reaction while a pressure of a reaction system is controlled to range from 0.1Torr to less than an atmospheric pressure, whereby a second silicon carbide powder having an average particle diameter of 0.1mum or less is obtained. A first silicon carbide powder having an average particle diameter of 0.1-10mum contains 0.5wt.% or more second silicon carbide powder. A sintered silicon carbide body is obtained by heating and sintering this mixture. The seal material made of the sintered body has a conductivity of an electric resistance of 1OMEGA.cm or less, a sintering density of 3.0g/cm<3>, and a three-point bending strength of 50.0kg/mm<2> or more. This seal material is cut into a cylindrical form, ground, and polished to be finished into a seal form. One end face thereof is subjected to electric discharge machining using electrodes, whereby a sealing part 2 is formed. |
