Simple and low-cost synthetic route for SiBCN ceramic powder from a boron-modified cyclotrisilazane

This study reports a simple and low-cost synthetic route for preparing SiBCN ceramic powder via pyrolysis of boron-modified cyclotrisilazane (BCTS). BCTS resins were synthesized by reacting boric acid with 1, 3, 5-trimethyl-1', 3', 5'-trivinylcyclotrisilazane (CTS) in the molar ratio of 1:1, 1:3, and 1:5. The boron modification in CTS resin resulted in optimum properties for preceramic polymers such as solubility in common solvents, processable viscosity (<20 cps) and high ceramic yield (>80 wt. %). The polymer to ceramic conversion was carried out at 1450 and 1650 degrees C under a nitrogen atmosphere. The study demonstrated that the changes in CTS concentration and pyrolysis temperature significantly affected the evolution of ceramic phases, morphology, and elemental composition which were thoroughly investigated through XRD, SEM, and HRTEM techniques. The results revealed the formation of beta-SiC, beta-Si3N4, and oxide ceramic phases with BCTS in the molar ratio of 1:1 and 1:3; whereas, beta-SiC, beta-Si3N4, and turbostratic BN(C) ceramic phases were obtained with BCTS in the molar ratio of 1:5.