Al/SiC/PCS先驱体裂解-反应机理研究

REACTION PYROLYSIS MECHANISM OF Al/SiC/PCS PRECURSOR SYSTEM

以热重 -差热 (TG -DTA)、流动氮气气氛中不同裂解温度下产物的X射线衍射 (XRD)和元素线扫描 (ELEM)方法研究了含活性填料Al,惰性填料SiC的聚碳硅烷 (PCS)先驱体的裂解 -反应机理。研究表明 ,PCS的裂解从 40 0℃左右开始 ,80 0℃时基本完全。体系由于裂解产生挥发性小分子而失重。当体系中含有PCS特别是SiC微粉时 ,Al的氮化温度会大大下降 ,转化率大大提高 ,SiC起着类似催化剂的作用。当裂解温度升高至 60 0℃时 ,Al微粉开始熔化 ,与SiC或PCS的中间裂解产物 [PCS]作用 ,形成中间体 [AlaCb]和 [Si]。随着温度的升高 ,中间体与保护气氛N2 发生氮化反应 ,形成AlN和SiC。当裂解温度上升至 10 0 0℃时 ,反应基本完成。

The reaction pyrolysis mechanism of polycarbosilane (PCS) precursor systems with active filler Al and inert filler SiC was investigated by TG-DTA, XRD and ELEM of the pyrolysis products at different temperatures under a flowing nitrogen stream. The results show that the pyrolysis of PCS began at about 400 ℃ and is basically completed at 800 ℃. Mass loss is caused due to the volatilization of small molecular. When PCS, especially SiC powders are contained, the nitridation temperature of Al decreases greatly with a much high conversion ratio from Al to aluminium nitride (AlN). Al powders were melting when the pyrolysis temperature increased up to 600 ℃, and reacted with the ambient SiC powders or the semi-pyrolysis products of PCS to form interphases, such as [Al a C b ] and , which reacted with nitrogen to produce AlN and SiC when the temperature further increases. The reaction is almost completed when the temperature increases up to 1 000 ℃.