陶瓷复合材料
( 国防科技大学 新型陶瓷纤维及其复合材料国防科技重点实验室, 长沙 410073)
摘 要: 以聚硅氧烷为先驱体, SiC为惰性填料, Al为活性填料, 考察了活性填料Al在聚硅氧烷转化制备Si-O-C复合材料中的应用。 研究发现: 600℃时,活性填料Al能与聚硅氧烷裂解产生的含碳小分子气体反应生成Al4C3, 800℃时能与N2反应生成AlN; 这2个反应同时伴有体积膨胀, 能有效弥补聚硅氧烷裂解时的线收缩。 活性填料Al的引入能起到增强作用; 含20%Al(体积分数)的SiC/Si-O-C复合材料的弯曲强度是不含Al的1.36倍; 活性填料Al的引入能显著改善SiC/Si-O-C复合材料的耐高温和抗氧化性能, 但不能提高其抗热震性能。
关键字: 活性填料; 铝; Si-O-C陶瓷;先驱体裂解
derived silicon oxycarbide composites
( Key Laboratory of Advanced Ceramic Fibers and Composites,College of Aerospace and Materials Engineering,National University of Defense Technology, Changsha 410073, China)
Abstract: Polysiloxane loaded with SiC as inert filler and Al as active filler, was pyrolyzed in N2 to fabricate Si-O-C composites, and the processing and properties of the filled Si-O-C composites were investigated. Al fillers can react with hydrocarbon generated during polysiloxane pyrolysis at 600℃ and N2 at 800℃ to create Al4C3 and AlN, respectively. The volume expansions resulting from the two reactions are in favor of the reduction in linear shrinkage and the improvement in flexural strength of SiC/Si-O-C composites. The flexural strength of Al-containing SiC/Si-O-C composites is 1.36 times of that of SiC/Si-O-C composites without Al at an Al filler content of 20%. The addition of Al fillers can remarkably improve the high temperature resistance and the oxidation resistance of SiC/Si-O-C composites, but not the thermal shock resistance.
Key words: active filler; aluminum; silicon oxycarbide ceramics; preceramic polymer pyrolysis