| 摘要 |
PROBLEM TO BE SOLVED: To obtain improved fracture toughness by changing at least one of the distribution density, diameter and length of the whisker to the inward direction of the whisker composite ceramic. SOLUTION: The objective product is a whisker composite ceramic in which the whisker distribution density is changed inward so that it may become 5-50 vol.% in the surface area bearing the toughens and 0-30 vol.% in the middle part bearing the strength. During the process that the ceramic powder and powder as a raw material for dispersed whiskers are mixed, molded and a sintered, the raw whisker material are allowed to react thereby forming whiskers in the ceramic. In this case, the amount of the whiskers formed in the molded product increases, as the initial relative density becomes lower, wile the formation of whiskers are suppressed as the initial relative density becomes higher. Thus, the initial relative density is controlled to 20-60 wt.% to produce the composite ceramic having the objective performance. The dispersed whisker raw powder is selected form Si3 N4 , SiO2 , C polycarbosilane as a raw material for SiC or Si3 N4 . |
