High-efficiency thermal insulation materials optimization of Al₂O₃f@Al₂O₃/RF/SiO₂

Due to the urgent need for high-efficiency thermal-insulating materials with excellent thermal and mechanical stability at high temperatures in aerospace, this study addressed the insufficient structural and mechanical properties of RF/SiO₂ aerogels under high-temperature conditions. We innovatively introduced Al₂O₃ into the aerogel matrix via aluminum isopropoxide hydrolysis to construct an Al₂O₃/RF/SiO₂ modified matrix, which was then combined with alumina fiber felt (Al₂O₃f) to create Al₂O₃f@Al₂O₃/RF/SiO₂. Based on this, aluminum content effects on aerogel pore structure evolution, thermal stability, insulation regulation, and composite mechanical enhancement were studied. Al₂O₃ improved aerogel thermal stability and strength. At Al/Si = 1.0:3.5, the aerogel had 90.47 m²/g surface area and 0.0388 W/(m·K) conductivity, from nanoporous tortuous pores. Thermal treatments showed alumina prevented pore collapse, preserving porosity. Alumina fibers increased composite compressive strength by 40 %, enhancing mechanics. At 400 °C, composite cold surface temperature was 88 °C, 4.3 % lower than unreinforced systems, demonstrating excellent insulation. In summary, this study successfully prepared Al₂O₃f@Al₂O₃/RF/SiO₂, significantly enhancing its thermal insulation and mechanical properties at high temperatures. In the future, it is expected to further optimize the material formulation and preparation process, expand the application of this composite in more high-temperature fields, and provide stronger material support for the development of related industries.