Patent ID: 8304078

Claim:
Chemically strengthened lithium aluminosilicate glass having high strength effective to resist fracture upon flexing, the glass having a composition comprising: SiO 2 and Al 2 O 3 , wherein the glass is characterized by having a surface compression of at least about 100,000 psi and a compression case depth of at least about 600 microns, wherein the glass is formed by chemically strengthening an untreated glass having a composition including Li 2 O in an amount ranging from about 3 to 9 weight % and Al 2 O 3 in an amount ranging from about 7 to 30 weight % and SiO 2 , and an annealing point temperature of at least about 580° C. prior to chemical strengthening, and wherein the glass is formed by a method comprising immersion of the untreated glass in a mixed potassium and sodium salt bath, containing greater than about 50 mole % potassium salt and less than about 50 mole % sodium salt, at a temperature ranging from about 450° C. to below the annealing point temperature of the untreated glass.