旋转CVI制备C/SiC复合材料

旋转 ＣＶＩ是在 ＣＶＩ原理基础上发展的一种制备 Ｃ／ＳｉＣ复合材料的新工艺，通过石墨衬底的旋转，使预制体的制备与基体的沉积同步进行，能有效消除一般ＣＶＩ工艺过程中存在的“瓶颈”效应．在自制的旋转 ＣＶＩ设备上实验，探索了旋转 ＣＶＩ工艺参数中 ＣＨ_３ＳｉＣｌ_３（ＭＴＳ）的流量与浓度、沉积温度和Ｃ布缠绕线速度对ＳｉＣ基体沉积速度，以及沉积温度对基体结构的影响．并在低压（５ｋＰａ）、高温 （１１００℃）、 ４００ ｍＬ·ｍｉｎ^－１ Ｈ_２、 ２００ ｍＬ·ｍｉｎ^－１Ａｒ、 ＭＴＳ４０℃与Ｃ布以１．１～３．５ｍｍ·ｍｉｎ^－１的线速度连续旋转的沉积条件下，实现了单丝纤维间微观孔隙、纤维束之间以及Ｃ布层间宏观孔隙的致密化同步完成．

Rapid Fabrication of C/SiC Composites Using Rotating Chemical Vapor Infiltration

Rotating chemical vapor infiltration (RCVI) is an improved process for fabricating C/SiC composites, and it is based on chemical vapor infiltration principle. In RCVI process, layer-by-layer of carbon cloth and deposition of matrix were done synchronously by rotating of a graphite axis, with the result that the bottle-neck effect of gas diffusion in traditional processes was eliminated. The effect of flux and concentration of methyltrichlorosilane (MTS, CH3SiCl3), deposition temperature and rotational linear velocity of carbon cloth on deposition rate of silicon-carbide matrix, and the effect of deposition temperature on structure of silicon-carbide matrix, were studied with lots of experiments. Three different kinds of pores, which are micro-gap around filaments, macro-holes due to weaving and spaces between plies of carbon cloth, were rapidly filled with SiC matrix at the same time. The optimal conditions for deposition are a low pressure of 5kPa, a high temperature of 1100C, 400 mL-1 and 200 mL-1 flow rates of H2 and Ar, respectively, a MTS temperature of 40C and a 1.13.5mm-1 rotational linear velocity of carbon cloth.