Polymer‐derived SiC–ZrC composite ceramic fiber prepared by the BCl3‐curing process

Abstract Continuous polycrystalline SiC–ZrC composite ceramic fibers were produced by the precursor route consisting of five processing steps: synthesis of the polymer, melt‐spinning, BCl3‐curing process, pyrolysis and heat treatment. Polyzirconocarbosilane (PZCS) were fabricated with liquid polycarbosilane (LPCS) and ziroconiumacetylacetonate (Zr(acac)4) at N2 atmosphere. The influence of employing BCl3 curing and air curing on the composition and structure of SiC–ZrC ceramic fibers was investigated. The crystalline SiC–ZrC fibers were obtained by the pyrolysis of cured fibers under N2 atmosphere and then treated at 1900°C for 1 h under Ar atmosphere. The results showed that BCl3 enabled the curing of PZCS green fibers, and B–O bonds can be detected in the fibers. Polycrystalline SiC–ZrC fibers were prepared by converting ZrO2 to ZrC via carbothermal reduction reaction during high‐temperature treatment. Compared to conventional air curing, fibers cured by BCl3 exhibit greater density, fewer defects and higher strength retention following treatment at 1900°C. After the fibers were oxidized at 1500°C for 1 h, a dense oxide layer of SiO2–ZrO2 was formed on the surface of the fibers, indicating excellent oxidation resistance. The fabrication of SiC–ZrC ceramic fibers is an effective approach to improve the high temperature performance and oxidation resistance of polymer‐derived SiC fibers.