The fabrication of porous corundum spheres with core-shell structure for corundum-spinel castables

Abstract

Abstract Porous corundum spheres (PCSs) that possess core-shell structure were fabricated by foaming and wet granulation method and used as aggregates to prepare the porous corundum-spinel castables (PCSCs). The microstructure and properties of PCS and PCSC have been studied. The results showed that the microporous shell and macroporous core were formed in PCS with the bulk density of 3.08 g · cm− 3 and the apparent porosity of 10.9%. In addition, the median pore diameter of PCS is 6.47 μm. The thermal conductivity of PCSC is 0.753 W/m · K at 1000 °C, and PCSC showed the higher corrosion index and better resistance to slag penetration than corundum-spinel castables (CSC) using the tabular corundum as aggregates. Compared with CSC, the bulk density of PCSC is decreased by 6.3% at 110 °C, 4.6% at 1550 °C, and the thermal conductivity decreased by 13.3–21.4% from 200 °C to 1000 °C. The results demonstrated that PCS with designed core-shell structure can achieve the trade-off between thermal conductivity and corrosion resistance.