“CVI+压力PIP”混合工艺制备低成本C／SiC复合材料

Low-cost C/SiC Composites Prepared by CVI+Pressure-PIP Hybrid Process

以低成本填料改性有机硅浸渍剂作为先驱体,采用“化学气相渗透法+压力先驱体浸渍裂解法”(CVI+P-PIP)混合工艺制备了低成本C／SiC陶瓷复合材料．研究了浸渍剂裂解机理,探讨了界面涂层对复合材料性能的影响．结果表明,填料改性有机硅浸渍剂裂解产物结构致密、陶瓷产率高;压力可提高填料改性有机硅浸渍剂的致密效率．混合工艺充分利用沉积 SiC基体和裂解SiC基体的致密化特点,有效缩短了制备周期． C／SiC／C三层界面不仅可降低纤维／基体之间结合强度界面,提高了复合材料韧性;而且减缓了氧化性气体扩散到碳纤维表面的速度,改善了复合材料的抗氧化性能．复合材料的抗弯强度达到455MPa,断裂韧性达到 15．7MPa·m-1／2．在1300℃空气中氧化3h,复合材料失重仅8．5％．

Low-cost C/SiC composites were prepared by ＂ CVI＋PIP ＂ combined process. A silicone impregnant with fillers was used in the PIP process. The pyrolysis mechanism of the impregnant and the properties of the composites were investigated. The results show that silicone impregnant with fillers has high pyrolysis yield and its pyrolysis product is dense, pressure can enhance the PIP efficiency of the fillered impregnant. ＂ CVI＋ P-PIP ＂ hybrid process makes use of the densification advantages of CVI process and PIP process, which can shorten the process cycle. C/SiC/C multilayered coating can decrease the bonding strength of the fiber/matrix interface, and it reduces the diffusing velocity of oxygen to the surface of carbon fibers. Hence the mechanical properties and anti-oxidation properties are improved. The flexural strength and fracture toughness （KIC） of the C/SiC composites are 455MPa and 15.7MPa·m^-1/2 respectively. The weight loss of the C/SiC composites is merely 8.5% after heated at 1300℃ in air 3h.