Boron-modified perhydropolysilazane towards facile synthesis of amorphous SiBN ceramic with excellent thermal stability

Abstract

SiBN ceramics are widely considered to be the most promising material for microwave-transparent 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 °C 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 °C. 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.

Fast Solution Blow Spinning of Lotus-Leaf-Inspired SiO2 Nanofiber Sponge for High Efficiency Purification

“…Organic polysiloxane is widely acknowledged for its solubility and high purity, which can enhance the homogeneity and performance of ceramic nanofiber products. − Recently, the influence of the blow spinning parameters and the polysiloxane precursor contents on the performance of the SiO 2 nanofibers are still elusive. Thus, it is necessary to explore the influence of different raw materials on the spinning process.…”

Polymer‐Derived High‐Temperature Nonoxide Materials: A Review

“…When it comes to B‐containing systems, perhydropolysilazane and borane dimethyl sulfide were pyrolyzed and annealed in N 2 atmosphere (without ammonolysis) at 1100, 1200, and 1300 °C. [ 126 ] The obtained amorphous SiBN ceramics demonstrated higher thermal stability and oxidation resistance than amorphous Si 3 N 4 . B in the Si–N network suppressed the crystallization of amorphous Si 3 N 4 and improved its thermal stability in the N 2 atmosphere.…”

Tailoring layered Csf/SiBCN composites with pseudoplastic fracture behavior: Strengthening and toughening mechanisms

“…The rapid development of aerospace and other high-tech fields has put forward higher requirements for thermostructural materials. 1 Silicoboron carbonitride (SiBCN) ceramics show low density, [2][3][4] high specific strength, 2 interesting functional properties, [5][6][7] and excellent hightemperature behavior [8][9][10][11][12][13][14][15][16][17] and are therefore one of the promising candidate materials for applications in the aerospace industry. However, the inherent brittleness of SiBCN ceramics causes catastrophic failure and limits its service reliability.…”