produto refratário fundido e vazado, forno de fusão de vidro e utilização de um produto refrat´rio fundido e vazado.

摘要

Fused and cast refractory product including on oxides basis in percent by weight and for a total of 100%: ZrO2+HfO2 complement to 100%; 3.5% to 6.0% SiO2; 0.7% to 1.5% Al2O3; 0.10% to 0.43% Na2O+K2O; 0.05% to 0.80% B2O3; less than 0.4% CaO+SrO+MgO+ZnO; less than 0.05% P2O5; less than 0.55% Fe2O3+TiO2; less than 1.5% other species. The ratio of percentages by weight of Al2O3/(Na2O+K2O) being greater than or equal to 3.5 and the ratio of percentages by weight of B2O3/(Na2O+K2O) being between 0.3 and 2.5.