Foam-gelcasting preparation and properties of high-strength mullite porous ceramics

The unique structure and excellent properties of porous materials enhance their prospects for application as catalyst supports, thermal insulation, and liquid filtration, and within biomedicine. In this study, mullite porous ceramics with high apparent porosity were successfully prepared using non-toxic and economical poly-γ-glutamic acid (γ-PGA) gelling system using the foaming method. The effects of the foaming agent (sodium dodecyl sulfate) and sintering temperature on the microstructure, apparent porosity, and mechanical properties of mullite porous ceramics were reported for the first time. The prepared mullite porous ceramics exhibited excellent properties with a porosity of up to 80.23%, corresponding to a bulk density and thermal conductivity of 0.62 g/cm3 and 0.17 W/(m·K), respectively. Moreover, the mullite porous ceramics contained significant amounts of unique near-spherical pores that contributed to a significant increase in compressive strength (6.1 MPa). In addition, the potential use of mullite porous ceramics as catalyst supports was validated by photodegradation of methyl orange solution.