Fabrication of Porous Mullite Ceramics with Different Phase of Alumina for Insulation Materials

This paper reports the effects of γ-Al 2 O 3 and α-Al 2 O 3 on the properties of lightweight insulation materials. The phase compositions, microstructure and mechanical properties of lightweight insulation materials are separately investigated by XRD, SEM and tabulate thermal conductivity apparatus methods. The results indicate that the increasing of the amount of γ-Al 2 O 3 is beneficial to improving the bulk density, compressive strength and acid resistance of the fired specimens. The fact negatively impacts on the increasing of the apparent porosity; however, it has no significant effect on the thermal conductivity of specimens. Meanwhile, the studies highlight that when the content of γ-Al 2 O 3 increases, the nucleation and growth of mullite is accelerated at high calcination temperature, which has positive effect on improving the physicochemical properties of lightweight insulation materials. And the γ-Al 2 O 3 -free SiO 2 glass phase system is guided by theoretical analysis of reaction conditions for non-catalytic system with Factsage modelling.