环境温度对二维编织SiC/SiC复合材料拉伸性能的影响研究

Effects of ambient temperature on tensile properties of 2D SiC/SiC composites

为了研究环境温度对陶瓷基复合材料拉伸性能的影响,在室温和800℃,1000℃,1200℃惰性气体保护环境下开展了二维编织SiC/SiC复合材料的拉伸试验。采用数字图像相关技术采集了高温环境下试件的变形数据。通过光学显微镜和扫描电子显微镜拍摄了试件的断口形貌。结果表明:800~1200℃内,二维编织SiC/SiC复合材料的拉伸应力-应变响应同样具有明显的双线性特征,初始线性段的弹性模量与室温测试结果相近,高温环境下第二线性段弹性模量低于室温环境;800~1200℃惰性气体环境下材料拉伸强度较室温环境低20%左右;温度主要影响材料中纤维与基体的结合状态和SiC纤维的强度。一方面,温度越高断口纤维拔出情况越严重;另一方面,温度越高SiC纤维强度越低,二维编织SiC/SiC复合材料强度也有所下降。

In order to study the effects of temperature on the tensile properties of ceramic matrix compos⁃ites,tensile tests of 2D SiC/SiC composites were carried out under inert gas environments at room temperature and high temperature of 800℃,1000℃and 1200℃.The deformation data of the specimen under elevated tem⁃perature environment is collected using digital image correlation technology.The fracture morphology of the speci⁃men was photographed by optical microscopy and scanning electron microscope.The results show that the tensile stress-strain response of the 2D SiC/SiC composites also has obvious bilinear characteristics in the range of 800℃to 1200℃.The elastic modulus of the initial linear segment at elevated temperature is similar to the room temperature test results,the elastic modulus of the second linear segment at elevated temperature is lower than that of the room temperature environment.The tensile strength of materials in the inert gas environment of 800~1200℃is about 20%lower than that of the room temperature environment.Temperature mainly affects the bind⁃ing state of the fiber to the matrix in the material and the strength of the SiC fiber.On the one hand,the higher the temperature,the more serious the pull-out of the fractured fiber.On the other hand,the higher the temperature,the lower the strength of SiC fibers,and the strength of 2D SiC/SiC composites also decreases.