基于环硼氮烷的高陶瓷产率SiBCN先驱体的合成与性能

聚合物先驱体转化法作为制备SiBCN陶瓷及其复合材料的重要途径,具有成型温度低、产物结构和组成可控等优点.设计合成合适的聚合物先驱体是提高陶瓷产率和性能的关键因素之一,本文采用三氯环硼氮烷(TCB)与乙炔基氯化镁进行反应,合成了乙炔基环硼氮烷,进而与二氯硅烷和二氯甲基乙烯基硅烷进行共氨解反应,制备了聚硼硅氮烷先驱体(PBSZ)并进行了高温裂解.采用综合热分析(TG-DSG)对其陶瓷化过程进行了分析,并采用XRD和SEM对陶瓷化产物的结构进行了表征.PBSZ在室温下是液态,易溶于二氯甲烷和氯仿等溶剂,可加工性优良.基于PBSZ先驱体的SiBCN陶瓷产率超过80%;陶瓷化产物在1400℃以下为无定形状态,在1500℃可形成由α-Si3N4,β-Si3N4,h-BN和SiO2晶体结构组成的陶瓷;陶瓷产物表面致密平整且具有优异的热稳定性和氧化性能,表明聚硼硅氮烷(PBSZ)有望成为高陶瓷产率和高性能陶瓷的重要先驱体.

Preparation and Characterization of SiBCN Precursor Derived from Borazine with High Ceramic Yield

The precursor derived ceramics is an efficient and widely used method for preparing the SiBCN ceramics and their composites.This method demonstrates many advantages,such as low molding temperature as well as tunable product structure and composition.In this study,a liquid polyborosilazane precursor(PBSZ)was prepared by the coammonolysis reaction of dichlorosilane,dichloromethylvinylsilane and borazine derivative,which attained by the reaction between ethynyl magnesium chloride and B-trichloroborazine(TCB).After subsequent curing and pyrolysis of PBSZ,the SiBCN ceramic material was obtained.The structures of the PBSZ and the cured PBSZ were characterized by FTIR and 1H-NMR.Ceramicization process of PBSZ and its structure were investigated by thermogravimetric analysis(TGA),X-ray diffraction(XRD)and SEM.The results exhibited that PBSZ could be soluble in common organic solvents such as dichloromethane and chloroform,along with excellent fluidity and processability.The ceramic yield of the SiBCN ceramics derived from PBSZ was observed to exceed 80%.The pyrolysis products sintered below 1400℃ exhibited the amorphous microstructures.At 1500℃,the derived ceramic materials turned out to containα-Si3N4,β-Si3N4,h-BN and SiO2 crystals.The SEM analysis revealed that the surface of the pyrolysis products was smooth and dense.Moreover,the SiBCN ceramics exhibited excellent thermal stability and oxidation resistance.