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    • 140. 发明公开
    • PRECERAMIC COMPOSITIONS AND CERAMIC PRODUCTS
    • PRECERAMIC组分和陶瓷产品
    • EP0340299A4
    • 1991-01-16
    • EP89900970
    • 1988-11-08
    • ETHYL CORPORATION
    • SEMEN, JOHNROGERS, JOHN, JOSEPH
    • C04B35/56C04B35/571C08K3/14C08K3/34C08L83/02C08L83/16
    • C08L83/16C04B35/571C08G77/62C08K3/14C08K3/34
    • Low density SiC ceramics having improved bending and specific strengths are prepared by (A) intimately mixing 50-85 % by weight of SiC powder with 15-50 % by weight of a preceramic polysilazane binder, (B) pulverizing the mixture to form particles having a particle size smaller than 105 micrometers, (C) separating from those particles any particles having a particle size larger than about 105 micrometers, (D) molding the resultant composition having a particle size not larger than about 105 micrometers, and (E) pyrolyzing the molded composition in an inert atmosphere to a temperature of 1200-1450°C. In a preferred embodiment of the invention, the preceramic binder is at least one polysilazane prepared by reacting an organodihalosilane with ammonia, treating the ammonolysis product with a basic catalyst which is capable of deprotonating an NH group that is adjacent to an SiH group, and quenching the resultant product with an electrophilic quenching reagent.
    • (A)将50-85重量%的SiC粉末与15-50重量%的预陶瓷聚硅氮烷粘合剂紧密混合,(B)将该混合物粉碎以形成具有改善的弯曲和比强度的低密度SiC陶瓷, (C)从这些颗粒中分离出任何粒径大于约105微米的颗粒,(D)将所得组合物的粒径不大于约105微米,和(E)热解 在惰性气氛中将模塑组合物加热至1200-1450℃的温度。 在本发明的优选实施方案中,陶瓷粘结剂是至少一种通过使有机二卤代硅烷与氨反应制备的聚硅氮烷,用能够使与SiH基团相邻的NH基团去质子化的碱性催化剂处理氨解产物, 用亲电子淬灭试剂得到的产物。