【摘要】 利用凝胶注模成型SiC基体层 ,以喷涂法、流延法、金属箔法、浸涂法分别加涂W ,W -2 % (质量分数 ,下同 )Co ,Ta,BN界面层 ,通过热压烧结制备了SiC/W ,SiC/W -2 %Co ,SiC/Ta ,SiC/BN层状复合材料 .在复合材料高温制备过程中 ,金属W ,W -2 %Co ,Ta与SiC反应生成了碳化物和硅化物 ,失去了金属塑性 ,未能实现裂纹尾流区桥接、残余应力增韧等金属界面层层状复合材料赖以大幅度提高其强韧性的增韧机制 ,其增韧效果仅与BN陶瓷界面层的增韧效果相当 .此外 ,研究表明 ,提高基体层力学性能可以显著提高层状复合材料的强韧性 .制备的SiC/BN层状复合材料的室温三点弯曲强度为 72 9.86± 114 .0 2MPa、室温断裂韧性为 2 0 .5 8± 2 .77MPa·m1 /2 ,其主要增韧机制包括裂纹分叉钝化、裂纹偏转、裂纹并行扩展以及裂纹尾流区片层拔出等更多还原

【Abstract】 SiC/W, SiC/W-2%Co, SiC/Ta, SiC/BN laminated composites in which SiC matrix layers were prepared by gel casting were fabricated by hot pressing technique. W, W-2%Co, Ta and BN layers which were prepared by spraying, doctor blading, gel casting, etc. respectively, as_received foil and coating were used as interfacial materials of laminated SiC matrix composites. At high temperature that was needed for the preparation, W, Ta reacted with SiC to form carbide and silicide, which had little plasticity and unable to achieve the toughness improvement of laminated composites by metal bridging and residual strain. However, it is found that the toughness and strength of the laminated composites are significantly increased by improving the properties of the matrix material. SiC/BN laminated composites with three point bending strength and nominal fracture toughness of 729.86±114.02 MPa and 20.58± 2.77 MPa·m 1/2 respectively are obtained. The main mechanism of enhancing toughness is attributed to crack bluntness, crack deflexion, crack parallel propagation and pull_out of matrix layer.更多还原