先驱体转化—热压烧结碳纤维增韧碳化硅复合材料的显微结构

采用ＸＲＤ，ＨＲＴＥＭ 和ＳＥＭ 等分析测试手段，研究了以聚碳硅烷（ＰＣＳ）为先驱体和粘结剂，Ｙ２Ｏ３ 和ＡｌＮ 为烧结助剂，采用先驱体转化－热压烧结法制备的Ｃｆ／ＳｉＣ复合材料的显微结构。结果表明，Ｙ２Ｏ３ 主要与ＰＣＳ的裂解产物以及ＡｌＮ 和ＳｉＣ表面的氧化物发生反应，形成有助于复合材料致密化的液相，而ＡｌＮ 则与烧结液相和ＰＣＳ之间通过反应－ 溶解－ 沉积过程，形成主要分布于界面相中的微小ＳｉＣ－ＡｌＮ 固溶体。正是由于含有一定量ＳｉＣ－ＡｌＮ 固溶体的富碳界面相使纤维与基体之间的结合适中，纤维易发挥脱粘和拔出作用，复合材料具有很好的力学性能

Microstructure of the Cf/SiC composites by precursor conversion-hot pressing sintering

The microstructure of the C f/SiC composites, prepared by precursor conversion hot pressing sintering with polycarbosilane (PCS) as precursor and binder and AlN Y 2O 3 as additives, was investigated using XRD, HRTEM and SEM. The results showed that Y 2O 3 reacted with the pyrolytic products of the PCS and the oxides on the surface of the AlN and SiC grains, forming the liquid phase assisting in the densification of the composites, and the fine SiC AlN solid solution was formed between AlN and the PCS through reaction dissolution precipitation at the grain boundaries and the fiber/matrix interface. Due to the presence of the carbon rich fiber/matrix interphase with a certain of SiC AlN solid solution, a desirable fiber/matrix interfacial bonding was obtained, which facilitated the debonding and pullout of the fibers. As a result, the composite exhibited excellent mechanical properties.