Effect of Impurities Control on the Crystallization and Densification of Polymer-Derived SiC Fibers

The polymer-derived SiC fibers are mainly used as reinforcing materials for ceramic matrix composites (CMCs) because of their excellent mechanical properties at high temperature. However, decomposition reactions such as release of SiO and CO gases and the formation of pores proceed above 1400 °C because of impurities introduced during the curing process. In this study, polycrystalline SiC fibers were fabricated by applying iodine-curing method and using controlled pyrolysis conditions to investigate crystallization and densification behavior. Oxygen and iodine impurities in amorphous SiC fibers were reduced without pores by diffusion and release to the fiber surface depending on the pyrolysis time. In addition, the reduction of the impurity content had a positive effect on the densification and crystallization of polymer-derived SiC fibers without a sintering aid above the sintering temperature. Consequently, dense Si-Al-C-O polycrystalline fibers containing β-SiC crystal grains of 50~100 nm were easily fabricated through the blending method and controlled pyrolysis conditions.

Research Progress on Microstructure Characterization of Silicon Carbide Fibers

Ceramic matrix composites have excellent properties such as high temperature resistance and oxidation resistance, and have good application prospects in the hot end parts of engines. In ceramic matrix composites, the microstructure composition of silicon carbide fibers determines their macroscopic properties. Therefore, this article takes silicon carbide fiber as the research object, summarizes the existing SiC fibers structure, composition, and morphology characterization methods, compares the development and advantages and disadvantages of XRD, SEM, TEM and other testing equipment analysis, and proposes The problems of sample preparation, surface defects and internal structure changes in the microstructure characterization of silicon carbide fibers are discussed, which provides a reference for the preparation of high-performance SiC fibers and the improvement of their characterization work.