New alkali-free aluminoborosilicate glass

摘要

A novel alkali-free aluminoborosilicate glass has the composition (by wt., on oxide basis) 57-60% SiO2, 6.5-9.5% B2O3, 14-17.5% Al2O3, 5-8% MgO, 1-4% CaO, 5-8% SrO, 0-3.5% BaO, 0.4-1.5% ZrO2, 0.4-1% TiO2, 0.1-0.5% CeO2 and 0.2-1% SnO2, the sum of MgO + CaO + SrO + BaO being 15-17%. Also claimed is an alkali-free aluminoborosilicate glass which can be produced in a float unit and which has the above composition, but which is free from arsenic oxide and antimony oxide down to impurity levels.