Corning Incorporated
Glass-ceramic articles with improved stress profiles

Abstract:

Glass-ceramic articles are manufactured by an ion exchange process that results in glass-based articles having improved stress profiles. A knee may be located at a depth of 3 microns or deeper. A compressive stress at a surface may be 200 MPa or more and at a knee may be 20 MPa or more. A non-sodium oxide may have a non-zero concentration that varies from the first surface to a depth and a depth of compression (DOC) may be located at 0.10t, or even at 0.17t or deeper. A two-step ion exchange (DIOX) includes, for example, a potassium bath in a first treatment to form a spike in a spike region of the stress profile, followed by a second treatment which includes, for example, a potassium and sodium mixed bath to maintain the spike and form a tail region of the stress profile. The glass-ceramic articles may thereby avoid developing a vitreous surface layer, which facilitates repeatable and reliable measurement of waveguide modes and determination of compressive stress in the surface (CS) and depth of the spike.