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

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 647 mu m. The thermal conductivity of PCSC is 0.753 W/m . K at 1000 degrees 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 degrees C, 4.6% at 1550 degrees C, and the thermal conductivity decreased by 13.3-21.4% from 200 degrees C to 1000 degrees C. The results demonstrated that PIS with designed core-shell structure can achieve the trade-off between thermal conductivity and con-osion resistance. (C) 2015 Elsevier Ltd. All rights reserved