| 摘要 |
PROBLEM TO BE SOLVED: To obtain a good sliding property for a long period without abrading both valve bodies, by forming a diamond form carbon raw film on the sliding surface of at least one side valve body through a silicon carbide film, as well as forming the two sliding valve bodies with a specific alumina ceramics. SOLUTION: Disk form base substances 27 and 37 to form a movable valve body 20 and a fixed valve body 30 are composed of an alumina ceramics including 94% or more of Al2 O3 , and SiO2 and the like as a sintering assistant. And in order to improve the adhesive property of a silicon carbide film 34 to the base substance 37, the pore ratio of the surface at the sliding surface 31 side of the base substance 37 is controlled less than 12.0%, the mean pore diameter less than 8.0μm, and the standard deflection of pore diameter less than 6.0μm. Furthermore, the pore ratio on the surface of the diamond form carbon film 35, that is the sliding surface 31, is controlled less than 12.0 %, the mean pore diameter less than 8.0μm, and the standard deflection of pore diameter less than 6.0μm. In this case, by using an ion plating method, the film can be formed at a low temperature, and a film with an even quality and an even form can be formed.
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