高温热处理对国产二代SiC纤维性能影响

As a key ceramic matrix composite material, SiC fiber has good high temperature resistance and oxidation resistance properties. High temperature heat treatment of SiC fiber is necessary in the preparation and actual service of high temperature composite materials. In order to understand the performance of SiC fiber during high temperature process and high temperature service process, through the high temperature argon and air treatments of SiC fiber, the influence of heat treatment on the tensile properties and microstructure properties of SiC fiber was analyzed, and the process performance and service performance of SiC fiber were investigated. In this study, the domestic second-generation SiC fibers were subjected to argon and air heat treatments at 1 000 ℃ for 30 h, and the tensile properties of the fibers were tested by fiber electronic strength tester. The microstructure and chemical composition evolution of the SiC fibers were tested and analyzed by means of scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectrometer. The relationship between the oxidation process of SiC fibers at high temperature, the variation of fiber surface, and the deterioration of the mechanical properties was discussed. Results show that the properties of the domestic second-generation SiC fibers were basically unchanged under the conditions of argon environment and heat treatment (1 000 ℃, 30 h), and the increase in crystallinity of SiC micro-crystal in the fiber was useful for its performance improvement. While the air environment and heat treatment (1 000 ℃, 30 h) led to the surface oxidation of the SiC fibers with SiO₂ layer and porosity, and the surface of the initially smooth fiber became roughness, resulting in decrease in the tensile strength of the SiC fiber by about 26%.