FUSED CAST PRODUCTS BASED ON ALUMINA-ZIRCONIA-SILICA WITH ANIMPROVED MICROSTRUCTURE

摘要

Oxidized alumina-zirconia-silica (AZS) refractories containing 40 wt% to 5 5 wt% Al2O3, 32 wt% to 45 wt% ZrO2, 10 wt% to less than 16 wt% SiO2 and 1 wt% to 3 wt% of an alkali metal oxide selected from Na2O, K2O and mixtures thereof ha ve a microstructure essentially comprising alpha-alumina crystals, free zirconia crystals, eutectic crystals and an intercrystalline vitreous phase. At least in an active area, more than 20% by number of the free zirconia crystals have a dendritic shape and are interleaved with each other and with eutectic crystals and at least 40% by number of the dendritic free zirconia crystals have a dimension greater than 300 .mu.m.