PIP工艺制备的C/SiC复合材料的氧化行为

The Oxidation Behaviors of C/SiC Composites Prepared by Precursor Infiltration Pyrolysis Process

PIP工艺制备的C/SiC复合材料中SiC基体富碳,因此增强体和基体均容易氧化.碳纤维和无涂层保护C/SiC复合材料试样在400～1300℃的氧化速率随温度升高而加快,低温为反应控制,高温为扩散控制.CVD-SiC涂层保护C/SiC复合材料和由CVD-SiC层、自愈合层、CVD-SiC层三层涂层保护C/SiC复合材料在400～1300℃的氧化先随温度升高而加快,然后减慢.三层涂层在800～1300℃有非常好的保护效果.扫描电镜照片显示自愈合层的玻璃态物质进入涂层裂纹中,填充裂纹且阻挡氧的通过,从而有良好的抗氧化保护效果.

C/SIC composites fabricated by precursor infdtration pyrolysis process are prone to oxidation above 400℃. Their oxidation behaviors have been researched on. The oxidation loss of C fiber textiles or C/SiC composites without coating increases at 400℃ to 1300℃. However,the oxidation loss of C/SiC composites with CVD-SiC coating or three-layer coating, respectively CVD-SiC layer, selfsealing layer and CVD-SiC layer, at first increases at 500℃ to 700℃, then decreases at 800-1300℃. Oxidation loss of C/SiC composites with three-layer coating are less than 6.4% at 800 - 1300℃ for 288h. SEM photographs indicate vitreous self-sealing layer filling in cracks.