Temperature-dependent microstructure and phase evolution of iron-containing SiC fibers

Oxygen-free silicon carbide (SiC) fibers were prepared by using polycarbosilane and iron pentacarbonyl [Fe(CO)5] as the raw material. The developments in microstructure and phase of the fibers upon the selected heat-treated temperatures were studied by XRD, FTIR, DTA-TG, SEM, and TEM techniques. The results revealed that the sintering of SiC fibers was promoted by introducing small amount of Fe. The iron-containing nanoparticles existed in the form of α-Fe in the SiC fibers pyrolyzed below 1000 °C. Above 1200 °C, most of the iron-containing nanoparticles existed in the form of Fe3Si. The SiC grains became obviously coarse above 1600 °C due to the decomposition of SiCxOy. After being sintered at 1800 °C, the final iron-containing SiC fibers were oxygen-free and remained dense.