High Thermal Expansion Phosphate Glasses. Part 2

The chemical durability of phosphate glasses can be improved by adding oxides such as Al2O3 or PbO. The general compositions investigated were M2O-MO-M2O3-P2O5, where M2 = Ag2O, Na2O, or K2O, MO = BaO or PbO, and M2O3 = Al2O3 or Fe2O3. Ag2O and PbO resulted in important improvements in chemical durability while maintaining high thermal expansion. Many glass compositions in the system had a thermal expansion coefficient of 180 to 210 x 10-7/deg C and a dissolution rate in deionised water at 70°C of \u3c10-7 g/cm2 min. Some of these compositions appeared to be good candidates for sealing glasses