Effect of sintering atmosphere on properties of near stoichiometric silicon carbide fibers

The excellent properties of near‐stoichiometric silicon carbide (SiC) fibers make them promising materials for applications in the aerospace and nuclear industries. However, the presence of a small amount of oxide phase and free Si within the fiber seriously affects its high‐temperature resistance. In this study, different near‐stoichiometric SiC fibers were prepared via sintering in nitrogen and boron atmospheres. The effects of the sintering atmosphere on the composition, structure, and properties of near‐stoichiometric SiC fibers were studied using mechanical property analysis, elemental analysis, X‐ray photoelectron spectroscopy, Auger electron spectroscopy, and high‐temperature resistance in Ar and air. The results showed that sintering in a boron atmosphere resulted in the introduction of a small amount of boron on the SiC fiber surface, while the internal composition and structure of the fibers were not significantly affected by the sintering atmosphere. When treated at high temperatures in Ar, the presence of boron prevented the formation of large SiC grains on the fiber surface, resulted in a denser fiber structure, and improved its high‐temperature resistance in an Ar atmosphere without reducing its oxidation resistance.