Opacifier embedded and fiber reinforced alumina-based aerogel composites for ultra-high temperature thermal insulation

摘要

A novel method was developed to uniformly disperse sub-micron TiO2 opacifier into fiber reinforcements using agar and silica as binders via freeze drying. TiO2 opacifier/ fiber/ alumina-based aerogel ternary (TFA) composites with high strength and excellent high-temperature thermal insulation were successfully prepared by sol-gel route, impregnation process and supercritical fluid drying. The microstructure, mechanical and thermal insulation properties of TFA composites were investigated comprehensively. The results show that the mechanical property of TFA composites can be significantly enhanced by mullite fiber felt and the incorporation of SiO2 binder. The effect of TiO2 opacifier on the high-temperature thermal conductivity was studied by adjusting the content of TiO2 from 0 to 15 wt%. The obtained TFA composites exhibit high Young's modulus of up to 3.58 MPa and low high-temperature thermal conductivities of 0.129 W/m.K at 800 degrees C and 0.168 W/m.K at 1000 degrees C, respectively. The mechanism of heat transfer in TFA composites at high-temperature was also analyzed.