BACKGROUND

The disclosure relates to an ion exchangeable glass with high rates of ion exchange. More particularly, the disclosure relates to an ion exchanged glass in which a surface compressive stress is achievable with reduced ion exchange times. Even more particularly, the disclosure relates to such glasses that, when ion exchanged, are resistant to surface damage.

Glasses are used in as protective covers for electronic displays and the like. As such, glasses that are used in these applications must be resistant to damage caused by impact.

SUMMARY

Ion exchangeable glasses containing SiO2, Al2O3, Na2O, MgO, B2O3, and P2O5are provided. The compressive stresses of these ion exchanged glasses are greater than 900 megapascals (MPa) at a depth of 45 or 50 microns (μm) with some glasses exhibiting a compressive stress of at least 1 gigaPascals (GPa). The ion exchange rates of these glasses are much faster than other alkali aluminosilicate glasses. The ion exchanged glasses are resistant to damage caused by impact. A method of ion exchanging the glass is also provided.

Accordingly, one aspect of the disclosure is to provide a glass comprising SiO2, Al2O3, Na2O, at least one divalent metal oxide, B2O3, and P2O5, wherein Al2O3(mol %)≥B2O3(mol %)+P2O5(mol %).

A second aspect of the disclosure is to provide an ion exchanged glass comprising SiO2, Al2O3, Na2O, at least one divalent metal oxide, B2O3, and P2O5, wherein Al2O3(mol %)≥B2O3(mol %)+P2O5(mol %). The ion exchanged glass has a compressive layer having a compressive stress of at least about 900 MPa. The compressive layer extends from a surface of the glass to a depth of layer of at least about 45 μm.

A third aspect is to provide a method of ion exchanging a glass. The glass comprises SiO2, Al2O3, Na2O, at least one divalent metal oxide, B2O3, and P2O5, wherein Al2O3(mol %)≥B2O3(mol %)+P2O5(mol %). The method includes providing an ion exchange bath comprising KNO3. The ion exchange bath is at a temperature in a range from about 410° C. to 470° C. The method also includes ion exchanging a glass in the ion exchange bath for a time period of up to about four hours. The ion exchanged glass has a layer under a compressive stress of at least 900 MPa. The layer extends from a surface of the glass to a depth of layer of at least about 45 μm.

These and other aspects, advantages, and salient features will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

