China's Refractories

Abstract: In order to improve the service life of corundum lining for induction furnace, corundum dry ramming mix was prepared using brown corundum, fused magnesia, and α-Al2O3 micropowder as main starting materials, and the influence of α-Al2O3 micropowder additions (0, 1%, 2%, and 3%, in mass) on properties of corundum dry ramming mix was investigated. The results show that after heat treating at 1 600 ℃, with the increase of α-Al2O3 addition, the permanent change in dimensions on heating of the specimens decreases firstly and then increases, bulk density increases, apparent porosity decreases, and the crushing strength declines firstly and then enhances; when the addition of α-Al2O3 is 2 mass%, the permanent change in dimensions on heating of the specimens is relatively small and the crushing strength decreases to 22.8 MPa. The XRD and SEM results show that after firing at 1 600 ℃ for 3 h small granular magnesium aluminate spinel forms and is well-distributed, which enhances the density.

Key words: α-alumina micropowder, corundum, ramming mix, intermediate frequency induction furnace