Si-C-N微粉的硅氨烷先驱体的合成及气化行为

SYNTHESIS FOR PRECURSOR OF NANO SI(C,N) COMPOSITE POWDER AND ITS GASIFICATION BEHAVOR

研究了用气相裂解法制备Si－C—N复合纳米微粉时CH3SiHCl2氨解产物先驱体的合成及形成气溶胶时的行为，结果表明：合成温度对先驱体的摩尔质量有较大的影响，摩尔质量随红解温度的降低而增大；在温度较高时（10℃）合成的先驱体的摩尔质量小，分子内端基存在较多的-NH2基因，在气化时-NH2基团与-Si-H交联而使残余物增加；在-10℃时合成的先驱体摩尔质量较大，分子内端基上-NH2基团较少，在气化时残余较少；CH3SiHCl2氨解产物分子内存在较活泼Si－H、N—H基团，加热气化时发生部分交联反应。

An organosilazane precursor which can be product nanometer Si(C,N) compositepowders by aerosol method was studied. The reaction of CH3SiHCl2 with gaseous NH3 in diethylether solution results in the formation of silazane precursor. Reaction temperature has the great efFecton molecular weight of organosilazane precursor (determined by cryoscopy in benzene). 173g/mol at10 ℃, 302g/mol at 0 ℃, 470g/mol at -10 ℃; the process of gasification in high temperatureinvolves conversion of the liquid-phase precursor to a aerosol and crosslinking reaction of Si-H groupwith N-H group which established by thermogravimetric analysisi the ammonolysis products of lowmolecular weight (173g/mol at 10 ℃) organosilazane precursor consists a lot of -NH2 group species,which cumulative weight loss was 81% at 500 ℃; the ammonolysis products of high molecular weight(470g/mol at -10 ℃) consist a lot of cyclic species [CH3SiHNH]n, which cumulative weight loss was91% at 500 ℃.