SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric constant.This work focuses ...SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric constant.This work focuses on the synthesis and ceramization of single-source precursors for the preparation of SiBN ceramics as well as the investigation of the corresponding microstructural evolution at high temperatures including molecular dynamic simulations.Carbon-and chlorine-free perhydropolysilazanes were reacted with borane dimethyl sulfide complex at different molar ratios to synthesize single-source precursors,which were subsequently pyrolyzed and annealed under N2 atmosphere(without ammonolysis)to prepare SiBN ceramics at 1100,1200,and 1300℃with high ceramic yield in contrast to previously widely-used ammonolysis synthesis process.The obtained amorphous SiBN ceramics were shown to have remarkably improved thermal stability and oxidation resistance compared to amorphous silicon nitride.Particularly,the experimental results have been combined with molecular dynamics simulation to further study the amorphous structure of SiBN and the atomic-scale diffusion behavior of Si,B,and N at 1300℃.Incorporation of boron into the Si–N network is found to suppress the crystallization of the formed amorphous silicon nitride and hence improves its thermal stability in N2 atmosphere.展开更多
基金The authors would like to acknowledge Merck KGaA for the financial support of this research project.Wei Li acknowledges financial support from China Scholarship Council(No.201907040060)during his research at TU Darmstadt.Zhenghao Wu acknowledges the funding of Deutsche Forschungsgemeinschaft via the SFB-TRR 146“Multiscale Simulation Methods for Soft Matter Systems”,Project A8.
文摘SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric constant.This work focuses on the synthesis and ceramization of single-source precursors for the preparation of SiBN ceramics as well as the investigation of the corresponding microstructural evolution at high temperatures including molecular dynamic simulations.Carbon-and chlorine-free perhydropolysilazanes were reacted with borane dimethyl sulfide complex at different molar ratios to synthesize single-source precursors,which were subsequently pyrolyzed and annealed under N2 atmosphere(without ammonolysis)to prepare SiBN ceramics at 1100,1200,and 1300℃with high ceramic yield in contrast to previously widely-used ammonolysis synthesis process.The obtained amorphous SiBN ceramics were shown to have remarkably improved thermal stability and oxidation resistance compared to amorphous silicon nitride.Particularly,the experimental results have been combined with molecular dynamics simulation to further study the amorphous structure of SiBN and the atomic-scale diffusion behavior of Si,B,and N at 1300℃.Incorporation of boron into the Si–N network is found to suppress the crystallization of the formed amorphous silicon nitride and hence improves its thermal stability in N2 atmosphere.
