BAS/SiC基复合材料的制备及其显微组织的研究

Processing and Microstructure Characterization of BAS/SiC Matrix Composites

以BaAl2Si2O8(BAS)为烧结助剂,采用热压烧结工艺制备出致密的SiC基复合材料.实验结果显示,BAS是一种很有效的液相烧结助剂,促进了SiC基复合材料的致密烧结和SiC颗粒的长大.随着BAS含量的增加,复合材料的致密度,抗弯强度和断裂韧性都增大.40wt%BAS/SiC复合材料的室温抗弯强度和断裂韧性分别达到510MPa和7.0 MPa.m1/2.复合材料的主要韧化机制是裂纹的偏转、SiC颗粒的拔出和桥连.冷却过程中BAS的完全晶化有利于复合材料的高温力学性能.经测试,40wt%BAS/SiC复合材料在1 200℃仍保持很高的抗弯强度.

Dense silicon carbide （SiC）-based ceramics were obtained by hot-pressing using BaAl2Si2O8 （ BAS） as an additive. The results showed that BAS could serve as an effective liquid sintering aid to promote densification and facilitate the growth of SiC grains. The relative densities, flexural strength and fracture toughness of the composites increase with increasing the BAS content. The flexural strength and fracture toughness of 40wt% BAS/SiC composite could reach 510 MPa and 7.0 MPa · m 1/2, respectively. The main toughening mechanisms are crack deflection, crack bridging and SiC grain pullout. The complete crystallization of BAS is beneficial to the high temperature mechanical properties and the obtained 40wt% BAS/SiC composite could maintain the room strength up to 1 200℃.