Corning Incorporated
CHEMICALLY DURABLE, LITHIUM-FREE GLASS COMPOSITIONS

Abstract:

Chemically durable glass compositions are disclosed. In embodiments, the glass composition includes: 48 mol. % to 61 mol. % SiO.sub.2; 0 mol. % to 1 mol. % Al.sub.2O.sub.3; 7 mol. % to 20 mol. % B.sub.2O.sub.3; 9 mol. % to 16 mol. % R.sub.2O, where R.sub.2O is a sum of alkali oxides present in the glass composition; 9 mol. % to 15 mol. % Na.sub.2O; and 8 mol. % to 21 mol. % ZnO. The glass composition may be substantially free of Li.sub.2O. RO (mol. %)<0.5.times.ZnO (mol. %), where RO is a sum of the alkaline earth oxides in the glass composition. An average coefficient of thermal expansion of the glass composition is 75.times.10.sup.-7/.degree. C. to 88.times.10.sup.-7/.degree. C. over a temperature range from about 20.degree. C. to about 300.degree. C. The glass composition comprises a softening point less than or equal to 660.degree. C. The glass composition comprises a hydrolytic resistance of class HGA1 or class HGA2 according to ISO 720:1985.