W/SiC界面反应层对SiC纤维拉伸断裂行为的影响

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

摘要:

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300 nm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

Abstract:

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