Effect of microporous corundum aggregates on microstructure and mechanical properties of lightweight corundum refractories

This study presents a new lightweight corundum refractory (LCR) used for working linings of high-temperature furnaces. The LCR contained microporous corundum aggregates replacing tabular corundum aggregates in traditional corundum refractories (TCR). The median pore size of the microporous corundum aggregates was 4.20 mu m, while the bulk density was 20.3% lower than that of the tabular corundum aggregates. The microstructure, cold modulus of rupture (CMOR) and fracture behavior of the LCR in comparison with those of the TCR were analyzed by mercury porosimetry, SEM and three-point bending tests. The results showed that the LCR had a better bonding at the interface between the microporous corundum aggregates and the matrix, which increased the percentage of crack propagation within the aggregates. Thus, the mechanical properties of the LCR was effectively enhanced. Compared with the TCR, the LCR had an 8.2% lower bulk density, while a 64.9% higher CMOR and a 38.2% higher fracture energy were achieved.