| 摘要 |
PURPOSE:To obtain crystalline silicon nitride having high content of alpha type, providing a sintered material having improved high-temperature strength, by decomposing thermally polysilazane in an ammonia gas atmosphere at a specific temperature, and calcining it in a nonoxidizing atmosphere. CONSTITUTION:An organohalosilane and(or) tetrahalosilane is reacted with ammonia in an anhydrous organic solvent, to produce polysilazane. The prepared polysilazane is heated from 350 deg.C up to 1,000 deg.C in an ammonia gas atmosphere for >=2hr, so it is thermally decomposed. The decomposition product is successively heated up to 1,300-1,700 deg.C in a non-oxidizing atmosphere (e.g., ammonia gas, or nitrogen gas), and calcined to give the aimed alpha type crystalline silicon nitride. The prepared silicon nitride is suitably useful as a high-temperature part for ceramic engine, etc.
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