非晶SiBCN陶瓷先驱体的制备及结构的表征

Synthesis and Structure Characterization of Amorphous SiBCN Ceramic Precursors

采用先驱体裂解的方法制备出热稳定性能优异的SiBCN陶瓷。SiBCN陶瓷的聚合物先驱体是由(H2C=CH)Si(CH3)Cl2和BH3·SMe2反应制备出中间产物,再经氨解制备得到的。在氯的消除过程中变成一种交联键合的非晶结构。此聚合物热稳定性良好,当温度达到400℃左右时开始大量失重并放出甲烷,大约在1050℃时热解为非晶陶瓷。得到的高聚物的化学结构和组成用IR,TGA,DSC,XRD进行分析,采用SEM对SiBCN陶瓷的形貌进行表征,陶瓷表面光滑、致密,具有非晶的特征,并在XRD中获得证实。

Polymer derived SiBCN ceramics have attracted worldwide attention due to their extraordinary high temperature stability and excellent oxidation resistance performance. However, the polymer derived ceramics is hard to obtain by conventional means. In the present work, A simple synthesis route was proposed to produce the exceptionally thermal stable SiBCN-based ceramics. The organosilylborane was synthesized using dimethylsulphide borane and dichloromethylvinylsilane, then it is subsequently ammonolysised, and thus the polymer of the SiBCN was obtained. The product transforms to amorphous structure with crosslinked bonds because of the elimination of Cl atom. In addition, the ammonolysised polymer is thermochemical stable. It shows significant mass loss at 400 oC and emits methane, and then pyrolyzes into amorphous ceramic at 1050 oC. The chemical structure and the chemical composition were analyzed by IR, TGA, DSC and XRD, while the morphology of the SiBCN ceramics was characterized by SEM. The results indicate that the ceramics is smooth and dense. In addition, it shows typical feature of amorphous material, which is identified by the XRD patterns.