六苯基环三硅氮烷合成工艺的改进

用甲苯作溶剂，二苯基二氯硅烷与氨气反应得到六苯基环三硅氮烷。通过正交实验，获得适宜的工艺条件：二苯基二氯硅烷浓度0.96mol/L，反应温度111-112℃，氨气流量0.02m3/h，后处理用氨水溶解副产物氯化铵，六苯基环三硅氮烷收率达到91.1%，并经IR表征结构。     

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°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 β-SiC, β-Si₃N₄, and oxide ceramic phases with BCTS in the molar ratio of 1:1 and 1:3; whereas, β-SiC, β-Si₃N₄, and turbostratic BN(C) ceramic phases were obtained with BCTS in the molar ratio of 1:5.