Abstract: To possess the [SiN₃O] structure and low ceramization temperatures,polysiloxazane (PSOZ) precursors were prepared using triisocyanomethylsilicon [MeSi(NCO)₃] as the raw material by partial hydrolysis and ammonolysis reactions.The yield of disiloxane intermediate was increased by controlling the pH (4.7,5.4 and 5.9),material mole ratio (n(H₂O)∶n(MeSi(NCO)₃)=1∶3,1∶2 and 2∶3) and hydrolysis temperature (-10,-20,-30,-40 and -50 ℃) of MeSi(NCO)₃ hydrolysis reaction,thus increasing the ceramic yield of PSOZ precursors.The pyrolysis characteristics of PSOZ precursors were further studied.The results show that:(1)PSOZ precursors complete the inorganicization at 800 ℃; the silicomethyl [Si—CH₃] and isocyano [—NCO] in the sample are completely decomposed;after heat treatment at 1 400 ℃,ceramization begins,and Si₂N₂O microcrystals appear locally in the sample;after heat treatment at 1 600 ℃,highly crystalline Si₂N₂O ceramics are obtained;(2)under the conditions of pH of 4.7,n(H₂O)∶n(MeSi(NCO)₃) of 1∶2 and hydrolysis temperature of -40 ℃,the ceramic yield of the PSOZ precursor is the highest,57.1 mass%.

Key words: polysiloxazanes, inorganicization, isocyano, ceramization

摘要： 为了制备具有[SiN₃O]结构单元、陶瓷化温度低的聚硅氮氧烷(PSOZ)先驱体,以三异氰基甲基硅[MeSi(NCO)₃)]为原料,采用部分水解和氨解反应,制备了PSOZ先驱体。通过控制MeSi(NCO)₃水解反应的pH(4.7、5.4、5.9)、物料比[n(H₂O)∶n(MeSi(NCO)₃)=1∶3、1∶2、2∶3]和水解温度(-10、-20、-30、-40、-50 ℃),提高二硅氧烷中间体的产率,进而提高PSOZ先驱体的陶瓷产率,并研究了PSOZ的热解特性。结果表明:1)PSOZ在800 ℃时完成无机化,此时试样中的硅甲基(Si—CH₃)和异氰基(—NCO)完全分解;经 1 400 ℃热处理后,产物开始陶瓷化转变,局部出现Si₂N₂O微晶;经1 600 ℃热处理后,得到高结晶的Si₂N₂O陶瓷;2)在pH=4.7、n(H₂O)∶n(MeSi(NCO)₃)=1∶2,水解温度为-40 ℃的条件下制备的PSOZ先驱体的陶瓷产率最高,为57.1%(w)。

关键词: 聚硅氮氧烷, 无机化, 异氰基, 陶瓷化