硅树脂249的交联与裂解陶瓷化研究

CURING OF SILICANE RESIN 249 AND ITS PYROLYTIC CONVERSION TO CERAMIC

研究了硅树脂249（SR249）的交联与裂解行为．结果表明．SR249在250℃能自交联，其机理主要通过硅羟基脱水缩合实现。裂解产物组成为34．69％Si．37．99％C．27．32％O．SR249的裂解陶瓷化主要在470℃～1150℃范围．分为三个阶段．第一阶段在470℃～600℃区间．裂解活化能为23．32kJ／mol．由随机成核步骤控制裂解反应。第二阶段在720℃～800℃区间内，裂解活化能为196．95kJ／mol，由三维扩散步骤控制裂解反应．第三阶段在1000℃～1150℃区间内．裂解活化能为135．87kJ／mol，由随机成核步骤控制裂解反应。引入纳米级活性填料Al、Si进行裂解，可以减少裂解产物中的自由炭，形成Si—Al—O—C陶瓷。

The curing and pyrolysis behaviors of silicane resin 249 （SR249） were investigated in this paper. The self-curing of SR249 occurs at 250℃ with the mechanism of consuming silanol. The pyrolysis products consist of Si, O, C whose contents are 34. 69%, 27.32% and 37.99%, respectively. The pyrolysis of SR249 includes three stages during 470 ℃～1150 ℃. The first is during 470 ℃～600 ℃. The second is during 720 ℃～800 ℃. The third is during 1000 ℃～1150 ℃. The apparent activation energies of the three stages are 23. 32 kJ/mol, 196.95 kJ/mol and 135.87 kJ/mol, respectively. The pyrolysis mechanism functions of the three stages are Avrami-Erofeev equation, Ginstling-Brounshtein equation and Avrami-Erofeev equation, respectively. The rates of pyrolysis reactions of the three stages are controlled by random nucleation and growth, three-dimensional diffusion （cylindrical symmetry） and random nucleation and growth, respectively. The product of SR249 with active filler nano-Al/Si is Si-Al-O-C ceramic with fewer free C element.