Porous thermal insulation materials derived from fly ash using a foaming and slip casting method

Abstract

The paper introduces a new kind of thermal insulation material using coal fly ash as main raw material by the method of foaming and slip casting process. The foaming ability of the suspensions with solid loading of 30, 35 and 40wt% at different foaming agent additive levels were measured. The green bodies were then sintered under different sintering temperatures from 850°C to 1000°C for 2h following the steps of foaming and drying. Effects of solid loading of suspensions and sintering temperature on the porosity, compressive strength and thermal conductivity were investigated. The sintered bodies, with porosity from 86.3vol.% to 94.5vol.% and compressive strength from 0.43MPa to 1.01MPa, contained spherical pores with no preferred orientation. The thermal conductivity of the sintered thermal insulation material, measured by the transient plane source (TPS) at room temperature, could reach as low as 0.0511W/(mK). As an environmental friendly material, it is suitable for wall application to save energy.