Abstract: To provide a high-zirconia electrocast refractory in which occurrence of cracks in manufacture and occurrence of cracks in use as a furnace material is further reduced while maintaining extremely high corrosion resistance to molten glass. The high-zirconia electrocast refractory contains 96.7 to 98.5 mass % of ZrO2, 0.8 to 2.7 mass % of SiO2, 0 to 0.2 mass % of Na2O, 0.21 to 1 mass % of K2O, 0.1 to 0.4 mass % of Al2O3, and does not substantially contain B2O3, in terms of oxide, as a chemical composition, wherein contents of the Na2O and the K2O satisfy a relation of following Formula (1) 0.15 mass %?CK2O/2+CNa2O?0.6 mass %??(1) where CK2O is the content of K2O and CNa2O is the content of Na2O, and each of the contents is expressed by mass % in the refractory.

Abstract: To provide a high-zirconia electrocast refractory in which occurrence of cracks in manufacture and occurrence of cracks in use as a furnace material is further reduced while maintaining extremely high corrosion resistance to molten glass. The high-zirconia electrocast refractory contains 96.7 to 98.5 mass % of ZrO2, 0.8 to 2.7 mass % of SiO2, 0 to 0.2 mass % of Na2O, 0.21 to 1 mass % of K2O, 0.1 to 0.4 mass % of Al2O3, and does not substantially contain B2O3, in terms of oxide, as a chemical composition, wherein contents of the Na2O and the K2O satisfy a relation of following Formula (1) 0.15 mass %?CK2O/2+CNa2O?0.6 mass %??(1) where CK2O is the content of K2O and CNa2O is the content of Na2O, and each of the contents is expressed by mass % in the refractory.

Abstract: To provide a high zirconia fused cast refractory having high durability, which hardly has cracks at the time of production of the refractory, during the heating, by temperature changes during use and during the cooling at the time of suspension of operation. A high zirconia fused cast refractory which has a chemical composition comprising from 88 to 96.5 mass % of ZrO2, from 2.5 to 9.0 mass % of SiO2, from 0.4 to 1.5 mass % of Al2O3, from 0.07 to 0.26 mass % of Na2O, from 0.3 to 1.3 mass % of K2O, from 0 to 0.3 mass % by outer percentage of Li2O, at most 0.08 mass % by outer percentage of B2O3, and at most 0.08 mass % by outer percentage of P2O5, and contains B2O3+P2O5 in a content of at most 0.1 mass % by outer percentage.

Abstract: To provide a high zirconia fused cast refractory having high durability, which hardly has cracks at the time of production of the refractory, during the heating, by temperature changes during use and during the cooling at the time of suspension of operation. A high zirconia fused cast refractory which has a chemical composition comprising from 88 to 96.5 mass % of ZrO2, from 2.5 to 9.0 mass % of SiO2, from 0.4 to 1.5 mass % of Al2O3, from 0.07 to 0.26 mass % of Na2O, from 0.3 to 1.3 mass % of K2O, from 0 to 0.3 mass % by outer percentage of Li2O, at most 0.08 mass % by outer percentage of B2O3, and at most 0.08 mass % by outer percentage of P2O5, and contains B2O3+P2O5 in a content of at most 0.1 mass % by outer percentage.

Abstract: To provide a high zirconia fused cast refractory having high durability, which hardly has cracks during the heating, by temperature changes during use and during the cooling at the time of suspension of operation. A high zirconia fused cast refractory which has a chemical composition comprising from 86 to 96 mass % of ZrO2, from 2.5 to 8.5 mass % of SiO2, from 0.4 to 3 mass % of Al2O3, from 0.4 to 1.8 mass % of K2O, at most 0.04 mass % of B2O3, at most 0.04 mass % of P2O5 and at most 3.8 mass % of Cs2O and containing substantially no Na2O.

Abstract: To provide a high zirconia fused cast refractory which hardly has cracks, and has excellent durability and reusability, at the time of production of the refractory and during use for a glass melting furnace. A high zirconia fused cast refractory which has a chemical composition comprising from 85 to 95 mass % of ZrO2, at least 2.5 mass % of SiO2, at most 0.04 mass % of Na2O, at most 0.04 mass % of B2O3, and at most 0.04 mass % of P2O5, containing SrO as an essential component, and containing at least one of K2O and Cs2O, wherein contents of SrO, K2O and Cs2O satisfy the relations of the following formula (1) and (2) at the same time: 0.20?[0.638×CK2O+0.213×CCs2O+0.580×CSrO]/CSiO2?0.40??(1) 0.10?0.

Abstract: A high-zirconia cast refractory material which contains 85-95 wt % of ZrO2, 4-12 wt % of SiO2, 0.1 to less than 0.8 wt % of Al2O3, less than 0.04 wt % of Na2O, 0.01-0.15 wt % of K2O, 0.1-1.5 wt % of B2O3, 0.01-0.2 wt % of CaO, less than 0.4 wt % of BaO, less than 0.2 wt % of SrO, 0.05-0.4 wt % of Y2O3, and 0.3 wt % or less of Fe2O3 and TiO2 together, but does not substantially contain CuO and P2O5 (less than 0.01 wt %), such that the molar ratio of the glass-forming oxides (such as SiO2 and B2O3) to the glass-modifying oxides (such as Na2O, K2O, CaO, MgO, SrO, and BaO) is 20-100, said refractory material having an electric resistance being 200 ?·cm or higher after standing for 12 hours at 1500° C.

Abstract: A high-zirconia cast refractory material which contains 85-95 wt % of ZrO2, 4-12 wt % of SiO2, 0.1 to less than 0.8 wt % of Al2O3, less than 0.04 wt % of Na2O, 0.01-0.15 wt % of K2O, 0.1-1.5 wt % of B2O3, 0.01-0.2 wt % of CaO, less than 0.4 wt % of BaO, less than 0.2 wt % of SrO, 0.05-0.4 wt % of Y2O3, and 0.3 wt % or less of Fe2O3 and TiO2 together, but does not substantially contain CuO and P2O5 (less than 0.01 wt %), such that the molar ratio of the glass-forming oxides (such as SiO2 and B2O3) to the glass-modifying oxides (such as Na2O, K2O, CaO, MgO, SrO, and BaO) is 20-100, said refractory material having an electric resistance being 200 ?·cm or higher after standing for 12 hours at 1500° C.