W/SiC界面反应层对SiC纤维拉伸断裂行为的影响

采用直流电热化学气相沉积(CVD)法制备出高强度SiC纤维(W芯),采用拉伸试验、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等对SiC纤维的强度、相组成、断口特征及微观结构进行了分析。结果表明,CVD-SiC纤维主要由β-SiC组成;制备过程中W芯同SiC发生化学反应,产生厚度约300nm的界面反应层,且反应层处存在着较大的残余拉应力;高强度SiC纤维裂纹产生于W/SiC界面反应层处,而低强度SiC纤维的裂纹源多处于W芯内部或纤维表面。

Effect of W/SiC Interfacial Reaction Layer on Tensile and Fracture Behavior of SiC Fibre

High-strength SiC fibre(W core) was fabricated by DC heating chemical vapor deposition(CVD) method.The morphology,microstructure and fracture characteristics of the fiber were characterized by X-ray Diffraction(XRD),Scanning Electron Microscope(SEM) and Transmission Electron Microscopy(TEM).The strength of the fibre was also analyzed by tensile tests.The results show that the CVD-SiC fibre mainly consists of β-SiC.The interfacial reaction layer between W core and SiC layer is 300 nm in thickness and there is great thermo-residual tensile stress,which leads to the tensile strength degradation.High-strength SiC fibre cracking origin is in the W/SiC interfacial reaction zone while low-strength SiC fibre cracking is generated in the inside of W core or on the surface of the fibre.The existence of defects at W core or on SiC fibre surface leads to low tensile strength.