Constructing hierarchical porous SiC/SiO2 ceramics-based phase change composites with low thermal conductivity and high strength for aircraft thermal protection

The integration of phase change material (PCM) into aircraft thermal protection system (TPS) can dissipate aerodynamic heat by utilizing its sensible and latent heat, but there is a problem of leakage. Porous SiC ceramics with high-temperature resistance and low thermal conductivity are utilized to encapsulate high latent heat PCM, solving leakage issues and mitigating the high-temperature aerodynamic heating environment experienced by aircraft. In this study, low thermal conductivity porous SiC ceramics were prepared, where the addition of SiO 2 in the skeleton led to a 36% reduction in thermal conductivity, while the mechanical properties were improved by 129%. After loading the PCM, the thermal conductivity of the composite was only 0.402 W/(m·K), while the latent heat reached up to 231.07 J/g. Aircraft is subjected to space particles when serving in the space environment, therefore the effects of 60 Co γ-ray irradiation on composite PCMs were investigated. The results showed that irradiation induced a small number of point defects in the skeletons, which caused phase changing polyethylene glycol (PEG) molecular chain breakage and the production of new compounds, thereby inducing a decrease in the latent heat of the PEG composites, whereas there was no significant effect on the phase changing mannitol (Man) composites. This study may provide guidance for the application of composite PCMs in TPS.