C/Mullite/Si-C-N复合材料的组织结构及其弯曲行为研究

Structure and Flexural Behavior of C/Mullite/Si-C-N Composite

本研究制备出了以莫来石为界面层的炭纤维增强Si-C-N陶瓷基复合材料(C/Mullite/Si-C-N)。使用三点弯曲法研究了复合材料在室温、1300℃和1600℃时的弯曲断裂行为,利用扫描电镜(SEM)和透射电镜(TEM)观察了复合材料的组织和弯曲断口形貌。结果表明:在室温和1300℃时,C/Mullite/Si-C-N复合材料的断口呈现出明显的脆性断裂特征;而在1600℃时,则呈现出韧性断裂特征。1300℃时的弯曲强度高于室温强度,模量则与室温下的基本相等。1600℃时,复合材料的弯曲强度和模量都明显下降。与具有热解炭界面层的C/Si-C-N复合材料相比,采用莫来石界面后,C/Si-C-N复合材料的强度明显下降。

Carbon fiber reinforced Si-C-N matrix composite with a mullite interlayer（C/Mullite/Si-C-N） was fabricated.The flexural behavior of the composite was investigated at RT,1300℃ and 1600℃,respectively.The structure and fracture of the composite were observed by using scanning electron microscope（SEM） and transmission electron microscope（TEM） techniques.The results indicate that the fracture of the composite appears obvious characteristics of brittle fracture at RT and 1300℃,and features of gliding fracture at 1600℃.At 1600℃,both the flexural strength and the modulus show a remarkable decrease.The use of mullite interlayer makes the strength of C/Mullite/Si-C-N obviously lower than that of the C/Si-C-N with pyrolytic carbon interlayer.