Oxidation resistance and heat transfer simulation of MoSi₂-based coatings on carbon fiber reinforced C-Al₂O₃ aerogel composite

Fiber-reinforced aerogels with excellent properties such as low density and low thermal conductivity are potential thermal insulation materials. The slurry method and the embedding sintering method were used to fabricate MoSi₂-aluminoborosilicate glass coatings on the surface of a carbon fiber-reinforced C-Al₂O₃ aerogel composite under a low-oxygen atmosphere. The microstructure and phase composition of the coatings with different MoSi₂ contents before and after static oxidation were investigated. The resulting composite exhibited excellent radiating properties and outstanding oxidation resistance. The total emissivity of the as-prepared coatings was above 0.8185 in the wavelength range of 300–2500 nm. The sample with 40 wt% MoSi₂ in the outer coating had superior thermal endurance with a weight loss of only 0.54% after isothermal oxidation at 1200 °C for 180 min. This can be attributed to the optimum viscosity of the binder, which would relieve thermal stress defects and block oxygen diffusion. To further evaluate the thermal protection performance of the coatings, the heat transfer characteristics were simulated using the Fluent software package. [Figure not available: see fulltext.]