短切石英纤维增强氮化物基复合材料的微观结构及强韧化机理

Microstructures and Reinforced Mechanisms of Nitride Composites Reinforced by Chopped Silica Fibers

采用先驱体聚合物浸渍裂解法(Preceramic polymer impregnation pyrolysis,PIP)制备了短切石英纤维增强氮化物基透波复合材料(SiO2f/Si3N4-BN),对复合材料的显微结构和界面特性进行了研究,探讨了短纤维增强氮化物基复合材料的强韧化机理。力学性能测试表明复合材料弯曲强度、断裂韧性和断裂应变分别达到56.6MPa,2.3MPa·m1/2和0.462%,介电性能优良。扫描电镜(SEM)及选区能谱(EDS)分析结果表明,氮化物基体与短切石英纤维没有发生界面反应,界面结合适中,短纤维以纤维拔出及裂纹偏转的形式使基体增强和增韧。

The chopped silica fibers reinforced nitride composites （SiO2f/Si3N4-BN） for radar windows materials were prepared through PIP methods by infiltration and pyrolysis. The mechanical and dielectric properties, the fiber/matrix interface microstructure and the reinforcement mechanism were investigated. Results show that the composites possess excellent dielectric properties, whose flexural strength is 56.6 MPa, fracture toughness 2.3 MPa.m^1/2 and fracture strain 0.462%. Scanning Electron Microscopy （SEM） and Energy Dispersive Spectroscopy （EDS） illustrate that good fiber/matrix interface bonding, chopped fibers pull-out, crack deflections, a fiber-bridge and penetration matrix crack contribute to the high toughness.