| 摘要 |
PURPOSE:To obtain a high-density ceramic composition with hardly any shrinkage in calcining without requiring a degreasing step in a short time by blending silicon nitride powder and/or silicon carbide powder with a specific polysilazane, forming the resultant blend and calcining the resultant compact in a state of no calcining assistant. CONSTITUTION:Silicon nitride powder or silicon carbide powder or both are blended with a polysilazane capable of providing silicon nitride, silicon carbide or silicon nitride and silicon carbide in a calcining atmosphere at 800-2200 deg.C under a pressure of nitrogen and/or ammonia and the resultant blend is formed to afford a compact, which is then calcined in a state of no calcining assistant. For example, the following are cited as the above-mentioned polysilazane. That is a polysilazane, having a skeletal structure consisting of recurring units expressed by formula I and plural precursor residues having units expressed by formula II partially converted into structural units expressed by formula III, partially and mutually connected with structural units expressed by formula IV. In formulas I to IV, R1 to R4 represent hydrogen, lower alkyl group, (substituted) vinyl group, (substituted) allyl group, (substituted) lower aryl group, etc. |
