原位合成SiC-BN复合陶瓷

SiC-BN Ceramic Matrix Composites by In-situ Reaction

采用原位合成的方法设计并制备了SiC BN复合陶瓷。经理论计算及实验证明 ,在相对较低的温度(170 0°C)下即可成功实现预期的原位反应。复合陶瓷中生成了细小均匀的微米级SiC和BN颗粒 ,在添加剂较多的地方发现了纳米级的SiC晶粒。SiC BN系列复合陶瓷的抗弯强度和断裂韧性在含 2 0vol%BN时达到最大 ,分别为 311MPa和 4 .5MPa·m1 2 ,弹性模量和硬度随BN含量的增加而减小 ,B6 0复合陶瓷的弹性模量为 4 0 .8GPa,维氏硬度为 0 .5 5GPa。不含BN的B0复合陶瓷的断裂方式主要为穿晶断裂 ,含有BN的SiC BN复合陶瓷的断裂方式主要为沿晶断裂。

SiC-BN ceramic matrix composites have been designed and fabricated via in-situ synthetic reaction. By theoretical calculations and experimental methods, the anticipated in-situ reaction was proved enabled at relatively low sintering temperature of 1700℃. In the composites, fine SiC and BN particles disperse homogeneously, and nano-sized SiC can be found where the additives are more. For the SiC-BN composites, flexural strength and fracture toughness reached the maximum values when the content of BN is 20vol%, 311MPa and 4.5 MPa·m 1/2 , respectively. Moreover the elastic modulus and the hardness of the composites decreased with the increasing of content of BN, which are 40.8GPa and 0.55GPa for the B60 specimen. Intragranular fracture can be found in the B0 specimen, while intergranular fracture can be found in the composites containing BN.