Low thermal conductivity of porous Al2O3 foams for SOFC insulation

Ceramic thermal insulation is one of the important thermal management devices for SOFCs operating at medium temperatures (< 800 C). Colloidal dispersion, the direct foaming method, microwave drying, and sintering were used to prepare porous Al2O3 foams with a total porosity of 85-95%. The measurement of thermal conductivity by a hot-wire method was conducted. The effects of cell structure on the thermal conductivity were investigated with SEM and FTIR. By optimising the cell structures of Al2O3 foams, low thermal conductivities of 0.05 W/m.K at room temperature and 0.14 W/m.K at 800 C were achieved.