Corning Incorporated
Chemically strengthenable lithium aluminosilicate glasses with inherent damage resistance

Abstract:

A group of glass compositions in the Li.sub.2O--Al.sub.2O.sub.3--SiO.sub.2--B.sub.2O.sub.3 family that can be chemically strengthened in single or multiple ion exchange baths containing at least one of NaNO.sub.3 and KNO.sub.3 for a short time (2-4 hours) to develop a deep depth of layer (DOL). In some instances, the DOL is at least 70 .mu.m; in others, at least about 100 .mu.m. The ion exchanged glasses have a high damage resistance (indentation fracture toughness ranging form greater than 10 kgf to greater than 50 kgf) that is better than or at least comparable to that of sodium aluminosilicate glasses.