Preparation and characterisation of closed-pore Al2O3-MgAl2O4refractory aggregate utilising superplasticity
A novel high closed porosity Al2O3-MgAl2O4 refractory aggregate has been successfully fabricated by utilising superplasticity with Al2O3 and MgO as raw materials, SiC as high temperature pore-forming agent. The effects of the addition amounts of MgO and SiC on porosity, sintering behaviours, phase composition, pore size distribution and microstructure of the refractory aggregate have been investigated. The formation mechanism of the closed pore in the refractory aggregate has been discussed. The results showed that the MgO can improve the superplastic deformation ability of Al2O3-based ceramic at high temperature. With the content of MgO and SiC increased, the closed porosity and the pore size increased. The oxidation of SiC improved the sinterability of materials at the initial stage of sintering, and then the released gases due to the further oxidation of SiC promoted the formation of closed pores by motivating the superplastic deformation ability of Al2O3-based materials.