| abstract |
The present invention relates to a molten and cast refractory product comprising, in mass percentages based on oxides and for a total of 100% oxides: ZrO2 + Hf2O: complement up to 100% 4.5% <SiO2 <6.0% Al2O3 <0.80% 0.3% <B2O3 <1.0% Ta2O5 + Nb2O5 <0.15% Na2O + K2O <0.1% K2O <0.04% CaO + SrO + MgO + ZnO + BaO <0.4% P2O5 <0.05% Fe2O3 + TiO2 <0.55% other species of oxides, optionally included Y2O3: <1.5%, where Y2O3 <0.3%, with the ratio "A / B" of the mass contents AL2O3 / B2O3 between 0.5 and 2.0. Application to glass melting furnaces. |