Abstract: A process for producing fused alumina-zirconia grits includes mixing raw materials suitable to produce grits with the following chemical composition, in % by weight: ZrO2+HfO2: 10–60%, Al2O3: 38–90%, SiO2: <0.8%, and Impurities: <1.2%. The process also includes adding carbon and aluminum metal to the mixture of raw materials to obtain a charged batch containing, in % by weight,: Carbon: 0.4–1% Aluminum metal: 0.5–2.5%. The process further includes melting the charged batch in an electric arc furnace with a voltage of 175–205 V and a delivered specific electrical energy of 2.5 to 4 kWh per kg of charge.

Abstract: A process for producing fused alumina-zirconia grits includes mixing raw materials suitable to produce grits with the following chemical composition, in % by weight: ZrO2+HfO2: 10-60%, Al2O3: 38-90%, SiO2: <0.8%, and Impurities: <1.2%. The process also includes adding carbon and aluminum metal to the mixture of raw materials to obtain a charged batch containing, in % by weight,: Carbon: 0.4-1% Aluminum metal: 0.5-2.5%. The process further includes melting the charged batch in an electric arc furnace with a voltage of 175-205 V and a delivered specific electrical energy of 2.5 to 4 kWh per kg of charge.

Abstract: Oxidized alumina-zirconia-silica (AZS) refractories containing 40 wt % to 55 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 have 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 &mgr;m.

Abstract: Oxidized alumina-zirconia-silica (AZS) refractories containing 40 wt % to 55 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 have 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 &mgr;m.

Abstract: The invention covers a fused cast refractory material essentially consisting of .beta. alumina and having the following chemical analysis expressed as molar percentages:11.25% to 15.45% of at least one alkaline metal oxide selected from the group comprising Na.sub.2 O, Li.sub.2 O and K.sub.2 O provided that Na.sub.2 O represents at least 9.3%,0 to 2.97% SiO.sub.2,81.38% to 88.75% Al.sub.2 O.sub.3, andat most 0.2% impuritiesand in which .beta. alumina represents at least 98% of the crystallized phases.