【摘要】 化学气相沉积(CVD)法制备的S iC纤维是一类重要的增强体,广泛用于金属基复合材料。文中测定了国产CVD法S iC纤维在室温下的抗拉强度,采用扫描电镜观察和分析了纤维的表面和界面形貌及断口特征。研究结果表明,CVD法制备的S iC(W芯)纤维强度分布具有统计性,采用W eibu ll分布可以较好地进行描述,S iC纤维强度的W eibu ll模数分别为11.1~13.9和4.0~5.8,平均抗拉强度在2 750~3 150 M Pa之间。扫描电镜观察表明,在纤维的W芯和S iC之间存在着界面反应层,CVD法S iC呈粗的柱状晶生长,S iC纤维呈明显的脆性断裂特征,纤维的粗糙表面以及W芯和S iC之间的界面反应可能形成裂纹源。更多还原

【Abstract】 The statistical distribution of the tensile strength of the SiC fibers with W core manufactured in China by CVD(Chemical Vapour Deposition) method is studied in this paper.Tensile tests of Chinese CVD SiC fibers with W core were conducted at room temperature.The surface and interface morphology and fracture characteristics of the SiC fibers were observed with the aid of Scanning Electron Microscope(SEM).The results show that the tensile strength of the fibers can be described by Weibull distribution function.The Weibull modulus of the fibers is 11.1～13.9 and 4.0～5.8 respectively for two groups of the fibers and the average tensile strength is 2 750～3 150 MPa.SEM observation reveals the existence of an interfacial reaction layer between SiC layer and W core.The CVD SiC fibers are column-shaped coarse grains and the surface of the fiber is uneven,particularly so for the group of the fibers with lower Weibull modulus.A brittle fracture of the fibers can be seen clearly and it is possible that the cracking initiates at the interfacial reaction layer and at the uneven surfaces of the fibers.更多还原