Preparation and Properties of SiC Ceramic Aerogels with High Temperature Oxidation Resistance

In this study, vinyl hydrogenated polycarbosilane (VHPCS) was utilized as the polymer precursor, while 1,4-dioxane served as the solvent. Tert-butyl peroxybenzoate (TBPB) and cobalt 2-ethylhexanoate (COEH) were applied as the initiator and accelerator for VHPCS, respectively. These additives significantly enhanced the reactivity of VHPCS, enabling the preparation of VHPCS gel under low-temperature and ambient pressure conditions. SiC ceramic aerogels were subsequently produced by freeze-drying and ceramization of the VHPCS gel. The resulting aerogels exhibited a low density of 0.25 g/cm3, a thermal conductivity of 0.098 W/(m·K) at room temperature, along with excellent heat insulating property. Thermogravimetric analysis (TGA) demonstrated minimal mass loss when the samples were heated to 1000 °C in air, confirming their exceptional high-temperature oxidative stability. These characteristics are consistent with the superior thermostability reported for advanced SiC-based composites.