Superior Cycling Stability of Moisture-Resistant Silica Aerogel Thermal Insulation Composites via Hydrothermal-Assisted Drying Process

Abstract Fiber-reinforced SiO2 aerogel thermal insulation composites are low density, high-temperature resistant, and exhibit low thermal conductivity, making them widely used in aerospace, petrochemical, and related fields. However, when subjected to an alternating high-temperature and high-humidity (ATH) environment, these materials are prone to pore structure collapse, increased thermal conductivity, and consequent degradation of thermal insulation performance. To address this challenge, this study employed aqueous silica sol as the silicon source and prepared a moisture-resistant SiO2 aerogel thermal insulation composite (MSAC) via hydrothermal-assisted drying process. A quartz lamp radiation heating-rain exposure-drying (HRD) cycle was designed to simulate ATH environments. The evolution of the microstructure and thermal insulation properties of MSAC was systematically investigated before and after multiple HRD cycles. The results show that after undergoing five HRD cycles, the thermal conductivity of the material at room temperature (0.0467 W/(m·K)) and at 1000 °C (0.073 W/(m·K)) remained virtually unchanged from the initial values. Even when the number of cycles was increased to 10, the microstructure of the material remained stable, with thermal conductivity at room temperature and 1000 °C increasing only to 0.048 W/(m·K) and 0.091 W/(m·K), demonstrating excellent moisture resistance and cycling stability. The MSAC developed in this study offers new insights and feasible solutions for thermal insulation design in high-temperature, water-humidity-cycling environments, including petrochemical pipeline insulation, thermal management for new energy vehicle batteries, and thermal protection for aerospace vehicles.