| abstract |
Glass compositions characterized by consisting essentially on a percent by weight basis of 43-63% SiO2, 14-25% Al2O3, 0 to 30% CaO, 0 to 20% MgO, where the total CaO + MgO expressed as CaO mole equivalent is from 10 to 30% by weight and the total alkali metal oxide expressed as Na2O mole equivalent ranges from 5 to 15%. The log viscosity of these glasses at its liquidus temperature is at least 2.3 and the liquidus temperature ranges from about 2,035* to about 2,320*F. Cooling time for these glasses is less than 96 seconds, for example, in the range of 55 to 68 seconds. |