Microstructure and properties of inter-locked mullite framework prepared by the TBA-based gel-casting process

Inter-locked mullite frameworks (IM frameworks) were prepared by the tert butyl alcohol (TBA) -based gel-casting method. The inter-locked structure formed through fluorine-catalyzed gas-phase reaction. Inter-locked topaz structure first formed in the samples and then it transformed into inter-locked mullite structure. TBA's volatilization and gaseous reactants' running off, which acted as two kinds of “pore formers” in the gel-casting process, offered enough space for the mullite grains' anisotropic growth, and led to the porous structure's formation. The volume density, apparent porosity, specific surface area and compression strength of the samples that formed at 1100–1500 °C were found to be 0.53–0.59 g/cm3, 82.1–76.1%, 12.3–4.6 m2/g and 1.6–3.6 MPa, respectively, indicating that the IM frameworks are promising as high-temperature catalyst supports.