Method of increasing IOX processability on glass articles with multiple thicknesses
A method of producing glass-based articles having sections of different thicknesses is provided, where a maximum central tension in a thinner section is less than that of a thicker section. The method includes reducing the thickness of a region of a glass-based article that includes a compressive stress layer extending from a surface to a depth of compression to form a glass-based article with multiple thickness regions, and then ion exchanging the glass-based article to form a stress profile in the thinner region that has a maximum central tension that is less than a maximum central tension of a stress profile of the thicker region. The glass articles produced by the method are also provided.
1 . A glass-based article comprising:
a first region comprising a first thickness, a first compressive stress layer extending from a first surface to a first depth of compression, and a first central tension region comprising a first maximum central tension; and
a second region comprising a second thickness, a second compressive stress layer extending from a second surface to a second depth of compression, and a second central tension region comprising a second maximum central tension,
wherein the second thickness is less than the first thickness, and the second depth of compression is less than the first depth of compression,
wherein the first depth of compression divided by the first thickness is greater than or equal to 0.15 and the second depth of compression divided by the second thickness is less than or equal to 0.15,
wherein the second maximum central tension is less than the first maximum central tension, wherein the glass-based article is a component of a cover substrate for a display in a mobile consumer electronic device,
wherein the first compressive stress layer comprises a first compressive stress, the second compressive stress layer comprises a second compressive stress,
wherein the first compressive stress and the second compressive stress each have a maximum value greater than 650 MPa, and
wherein the second thickness comprises a varying metal oxide concentration gradient that extends through the entire second thickness.
2 . The glass-based article of claim 1 , wherein the first depth of compression divided by the first thickness is about 0.15, and the second depth of compression divided by the second thickness is about 0.15.
3 . The glass-based article of claim 1 , wherein the first depth of compression divided by the first thickness is substantially equal to the second depth of compression divided by the second thickness.
4 . The glass-based article of claim 1 , wherein the first compressive layer and the second compressive layer comprise a spike region where a stress profile has a slope greater than 10 MPa/μm.
5 . The glass-based article of claim 1 , wherein the second thickness is at least 100 microns less than the first thickness.
6 . The glass-based article of claim 1 , wherein the second thickness divided by the first thickness is in a range from about 0.05 to about 0.96.
7 . The glass-based article of claim 1 , wherein the second region is off-set from all edges of the glass-based article.
8 . The glass-based article of claim 1 , wherein the second thickness is greater than or equal to 20% of the first thickness and less than or equal to 30% of the first thickness.
9 . A glass-based article comprising:
a first region comprising a first thickness, a first compressive stress layer extending from a first surface to a first depth of compression, and a first central tension region comprising a first maximum central tension; and
a second region comprising a second thickness, a second compressive stress layer extending from a second surface to a second depth of compression, and a second central tension region comprising a second maximum central tension,
wherein the second thickness is less than the first thickness, and the second depth of compression is less than the first depth of compression,
wherein the second thickness comprises a varying metal oxide concentration gradient that extends through the entire second thickness,
wherein the second maximum central tension is less than the first maximum central tension, wherein the glass-based article is a component of a cover substrate for a display in a mobile consumer electronic device,
wherein the first compressive stress layer comprises a first compressive stress, the second compressive stress layer comprises a second compressive stress,
wherein the first compressive stress and the second compressive stress each have a maximum value greater than 650 MPa, and
wherein the first depth of compression divided by the first thickness is in a range from about 0.15 to about 0.23, and the second depth of compression divided by the second thickness is in a range from about 0.075 to about 0.15.
10 . The glass-based article of claim 9 , wherein a concentration of a metal oxide in the second region is about 0.5 mol % or greater.
11 . The glass-based article of claim 9 , wherein a concentration of a metal oxide is greatest at the first surface or the second surface and decreases substantially constantly to a point between the first surface and the second surface.
12 . The glass-based article of claim 11 , wherein the concentration of the metal oxide at the point between the first surface and the second surface is non-zero.
13 . The glass-based article of claim 9 , wherein the total concentration of the metal oxide is in the range from about 1 mol % to about 20 mol %.