Robust and exceptional thermal insulating alumina-silica aerogel composites reinforced by ultra IR-opacified ZrO2 nanofibers

Abstract

Fiber-reinforced alumina-silica aerogel composites (FASA), renowned for their high-temperature resistance, low thermal conductivity, and robust mechanical properties, have emerged as a promising candidate for aerospace thermal insulation, especially in harsh environments characterized by intense vibration and oxidation. However, a significant challenge persists in homogeneously doping opacifiers and minimizing thermal conductivity of FASA at elevated temperature, which remains a thorny issue. Herein, we propose a novel fiber-reinforced and opacified (FRO) strategy to fabricate the ZrO2 fiber-reinforced alumina-silica aerogel composites (ZFASA) that boast ultra-low thermal conductivity (0.031 W·m−1·K−1 at 1100 °C) and excellent mechanical strength (0.44 MPa for compressive strength at 10 % strain and 2.1 MPa for bending strength, maintaining intact even after being rolled by a 1.7 t car). Furthermore, ZFASA exhibits remarkable thermal stability, enduring quartz lamp and butane torch tests at 1300 °C without any obvious change. This work provides a simple yet effective FRO strategy, paving a new path for the preparation of thermal insulating aerogel composites. Consequently, the highly durable and exceptional thermally insulating ZFASA we have developed is poised to better satisfy the demands of the aircraft thermal protection systems in extreme heat environments.