Corning Incorporated
Damage resistant glass with high coefficient of thermal expansion

Abstract:

Ion exchangeable glasses having coefficients of thermal expansion (CTE) at least about 90.times.10.sup.-7.degree. C..sup.-1. The glasses undergo rapid ion exchange, for example, in a molten KNO.sub.3 salt bath to a depth of layer of greater than 30 microns in less than 2 hours at temperatures of 370.degree. C. to 390.degree. C. When ion-exchanged to a depth of layer between 30 to 50 microns, the glasses exhibit a Vickers median/radial crack initiation threshold exceeding 30 kilograms force (kgf). The glasses are fusion formable and, in some embodiments, compatible with zircon.