Fracture and scratch resistant glass articles
Embodiments of glass compositions, glass articles and chemically strengthened glass articles are disclosed. In one or more embodiments, the glass composition comprises Li 2 O, greater than about 0.9 mol % B 2 O 3 , Al 2 O 3 in an amount greater than or equal to 10 mol %, and from about 60 mol % to about 80 mol % SiO 2 . Embodiments of the chemically strengthened glass article include a first major surface and an opposing second major surface defining a thickness t, a compressive stress layer extending from the first major surface to a depth of compression greater than about 0.12 t, a maximum compressive stress of about 200 MPa or greater, and a Knoop Lateral Cracking Scratch Threshold greater than about 6 N, as measured on either one of the first major surface and the second major surface. Methods for forming such chemically strengthened glass articles are also disclosed.
1. A chemically strengthened glass article comprising:
a first major surface and an opposing second major surface defining a thickness t in the range from about 0.3 mm to about 1.5 mm,
a composition of alkalialuminosilicate comprising SiO 2 in an amount in the range from about 60 mol % to about 80 mol %; Al 2 O 3 in an amount greater than or equal to about 10 mol %; Li 2 O in an amount in the range from about 4 mol % to about 10 mol %; B 2 O 3 in an amount of 7.5 mol % or less; Na 2 O in an amount greater than the amount of Li 2 O and in the range of from about 4.5 mol % to about 12 mol %; a non-zero amount of P 2 O 5 ; and K 2 O in an amount of less than 2.0 mol %;
a compressive stress (CS) layer extending from the first major surface to a depth of compression (DOC) greater than about 0.12t,
wherein the CS layer comprises a maximum stress of about 200 MPa or greater, and
wherein the glass article comprises a Knoop Lateral Cracking Scratch Threshold greater than about 6 N, as measured on either one of the first major surface and the second major surface, and
wherein at least one of:
(i) the article survives a maximum surface impact force of from about 400N to about 851N, as measured by the Surface Threshold Failure Impact Force test;
(ii) the article survives an average edge incident impact force of from about greater than 200N to about 500N, as measured by the Edge Threshold Failure Impact Force test; and
(iii) the article survives an edge incident impact energy of from about greater than 0.43 J to about 1.3 J, as measured by the Edge Threshold Failure Impact Force test.
2. The chemically strengthened glass article of claim 1 , wherein the total amount of B 2 O 3 , P 2 O 5 , SiO 2 and Al 2 O 3 is about 80 mol % or greater; and the ratio of Li 2 O to the total amount of B 2 O 3 , P 2 O 5 , SiO 2 and Al 2 O 3 is less than 0.074.
3. The chemically strengthened glass article of claim 1 , wherein the amount of K 2 O is less than 1.0 mol %.
4. The chemically strengthened glass article of claim 1 , further comprising a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3.1, wherein the metal oxide comprises any one or more of Na 2 O, K 2 O, Rb 2 O, and Cs 2 O.
5. The chemically strengthened glass article of claim 4 , wherein the concentration of the metal oxide is non-zero and varies along the entire thickness.
6. The chemically strengthened glass article of claim 4 , wherein the metal oxide generates a stress along the thickness range.
7. The chemically strengthened glass article of claim 4 , wherein the concentration of the metal oxide decreases from the first surface to a value at a point between the first surface and the second surface and increases from the value to the second surface.
8. The chemically strengthened glass article of claim 1 , further comprising a maximum central tension in the range from about 40 MPa to about 100 MPa.
9. The chemically strengthened glass article of claim 8 , further comprising a Young's modulus of less than 85 MPa.
10. The chemically strengthened glass article of claim 1 , wherein the amount of SiO 2 is in the range from about 65 mol % to about 80 mol %.
11. A device comprising:
a housing having front, back, and side surfaces;
electrical components that are at least partially inside the housing;
a display at or adjacent to the front surface of the housing; and
a cover article disposed over the display, wherein at least one of the cover article and at least a portion of the housing comprises the chemically strengthened glass article of claim 1 .
12. The chemically strengthened glass article of claim 1 , wherein the composition is substantially free of Fe 2 O 3 .