Reusable, high specific surface areas, and excellent thermal stability Al2O3–SiO2 aerogel composites as high-temperature thermal insulators for radome applications

• Published in: Journal of alloys and compounds 2024-05, Vol.984, p.173990, Article 173990
• Main Authors: Ren, Yuhan, Zhang, Biao, Zhong, Zhaoxin, Ye, Jian, Zhang, Jiawei, Fang, Zhiyong, Ye, Feng
• Format: Article
• Language: English
• Subjects: Al2O3–SiO2 aerogels; Boehmite nanorods; Radome; Thermal conductivity; Thermal stability
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2024.173990

In this study, monolithic Al2O3–SiO2 aerogels with excellent thermal stability and high specific surface area were synthesized using boehmite nanorods (L=20–30 nm, D=3–5 nm). The high specific surface area of aerogels was maintained after calcination at 800 °C (663.54 m2/g), 1000 °C (486.91 m2/g), and 1100 °C (230.76 m2/g). The anti-sintering mechanism of the Al2O3-SiO2 aerogels was discussed. Thanks to the composite of Al2O3-SiO2 aerogel and mullite fibers, the disadvantages of brittleness and low strength of aerogel are overcome. The thermal conductivity of the composite is extremely low at 0.034 W/(m·K)-0.089 W/(m·K) (25 °C-1000 °C). Five muffle cycle back-temperature tests at 1000 °C and a butane blowtorch back-temperature test at 1350 °C also proved that the composites have excellent thermal insulation properties. Composites with excellent thermal insulation properties combined with lightweight, thinness, machinability, and good dielectric properties meet the need for high-temperature thermal insulating-wave transmitting integrated materials for hypersonic missile radomes. •Al2O3-SiO2 aerogels were prepared by boehmite nanorods as an aluminium source.•Boehmite nanorods imparted excellent high-temperature resistance to the Al2O3-SiO2 aerogels.•The thermal conductivity of composites is extremely low at 0.034 W/(m·K)-0.089 W/(m·K) (25 °C-1000 °C).•Composites allow for multiple reuses at 1000 °C and use at 1350 °C.