Mixed oxide aerogels with high performance insulation properties for high temperature space application

Abstract

Aerogels itself have already proven their outstanding thermal performances and insulative properties. However, classical silica aerogels often are limited in their application due to melting and/or heavy sintering effects. By these structural changes and reconstructions the properties of the aerogels are lost. New space-related applications require higher thermal stabilities although only for short periods of time. Within this work we present the development and performance studies of fiber reinforced mixed metal oxides aerogels as ablator material for potential space applications. The new type of fiber reinforced composite is directly compared to a pristine high temperature fiber insulation, an fiber reinforced aerogel as well as an fiber reinforced and opacified aerogel. As most important parameters the processability, the thermal stability as well as thermal conductivity is presented. Thermal loads are imeeted in an arc-heated facility in order to analyze the high-temperature stability of the pure oxidic aerogels and mixed oxide SiO2 / Al2O3 fiber reinforced aerogels. All aerogels and compared fiber materials were examined in terms of temperature depending thermal conductivity to the point of failure, temperature transition through the material during the single-sided thermal treatment, crystallization behaviour by means of X-Ray-diffraction and their microstructure using SEM. Concluding, it can be stated that mixed metal oxides show the highest stability towards short-term temperature and also the temperature at the backside of the specimen increases least fast.