GLASS COMPOSITIONS THAT RETAIN HIGH COMPRESSIVE STRESS AFTER POST-ION EXCHANGE HEAT TREATMENT

摘要

Ion exchangeable glasses containing SiO₂, Na₂O, MgO, and, optionally, at least one of Li₂O and ΖrΌ₂. These glasses are also free of at least one of B₂O₃, K₂O, CaO, and P₂O₅. These glasses may be ion-exchanged to achieve a depth of compressive layer of at least about 40 μιη or up to about 50 μιη and a maximum surface compressive stress of at least about 950 MPa, in some embodiments, at least 1000 MPa and, in other embodiments, at least about 1100 MPa. The ion-exchanged glasses, when subsequently heat-treated, have a retained compressive stress of at least about 600 MPa at the surface of the glass and, in some embodiments, at least about 750 MPa. The glasses also exhibit high levels of durability when exposed to strong acid.