Rapid gel preparation of layer-column structured MgAl2O4 spinel aerogel with low thermal conductivity and enhanced high-temperature stability

Abstract

Oxide aerogels with low density, high porosity and low thermal conductivity are important for high-temperature thermal insulation. However, the synthesis of oxide aerogels that can be used in oxygen containing environment at temperatures exceeding 1300 °C is of a challenge. In this study, MgAl₂O₄ spinel aerogels (MASAs) were prepared by a novel rapid gel method with MgSO₄·5 Mg(OH)₂·3H₂O whiskers and aluminum sol as starting materials after 3 h firing at 1200 °C. The prepared MASAs have a unique “Layer-Column” three-dimensional structure and excellent thermal insulation up to 1950 °C, high porosity (98.4 %), low thermal conductivity (0.029 W·m⁻¹·K⁻¹ at room temperature), and high mechanical strength (311 kPa). The line shrinkage of as-prepared MASAs is only 7 % after secondary sintering at 1500 °C for 30 min. Additionally, after being scorched with an oxyacetylene flame at 1950 °C for 10 min, MASAs still maintain their original shape and excellent thermal insulation, demonstrating their amazing high-temperature thermal insulation properties. The excellent high-temperature stability and thermal insulation properties of as-prepared MASAs make them ideal thermal insulation candidates in ultrahigh-temperature fields.