Mo‐doped hollow Si ₃ N ₄ /SiC ceramic fiber composites for high temperature heat insulation and oxidation resistance

Abstract Silicon‐based ceramic composites have shown great potential in aerospace due to the favorable general properties. Compared with solid fiber materials, the hollow structure of silica‐based ceramic fiber shows better thermal insulation properties and has a wider range of applications. In this paper, Mo doped Si ₃ N ₄ /SiC ceramic fiber composites with hollow structure were obtained by coaxial electrospinning and polymer‐derived ceramics routine with polysilazane (PSN) as the precursor, MoSi ₂ powder as filler. The effects of pyrolysis temperature on the morphology and properties of the fibers were investigated. Benefitting from the preferred hollow structure, the obtained Mo doped hollow Si ₃ N ₄ /SiC ceramic fiber composites show favorable thermal insulation property (0.0367–0.0411 W·m ⁻¹ ·K ⁻¹ at room temperature). Besides, the doping of molybdenum provided satisfied oxidation resistant property due to the liquid phases formed during the oxidation process, which can effectively fill the cracks and voids generated by the thermal stresses, acting as a repairing agent and preventing further oxidation. Meanwhile, the oxide layer formed can also slow down the oxidation process by blocking oxygen molecules from penetrating further into the composites.