化学气相渗（CVI）碳化硅工艺研究

Study on CVI Process of SiC

对均热法、热梯度法和压差－温度梯度法三种化学气相渗ＳｉＣ工艺进行了研究，结果表明：三种方法制备周期依次缩短。均热法适合制备形状复杂的样品，提高沉积效率靠增大沉积炉和多放样品来实现，整个过程受气体自由扩散所控制；热梯度法适合制备形状简单、规则的薄壁试样，每炉只能做一个，过程主要受样品内外温度梯度所控制，用该法可以制备出成分连续变化的功能梯度材料；压差－温度梯度法适合制备板状、圆筒状厚壁样品，过程受样品两侧的温度差和气体压力差所控制。三种方法各有优缺点。根据需要可灵活运用。

The fabrication processes of carbon fiber reinforced SiC composites by CVI methods includingisothermal, thermal-gradient and pressure-temperature gradient have been described in this paper.CVIprocesses induce highly controlled reactions between vapor-phase reactants within hermetic chambers.Inisothermal process and thermal-gradient process the CVD gases diffuse into the preform,while in pressure-temperature gradient process the CVD gases are forced into the preform by a pressure gradient.Theprocessing cycles were successively reduced.