Glass article

Abstract

A glass article includes a glass core layer and a glass cladding layer adjacent to the core layer. A coefficient of thermal expansion (CTE) of the core layer is greater than a CTE of the cladding layer. The core layer has a tensile stress, and the cladding layer has a compressive stress. A retained strength of the glass article is a strength determined after abrasion of an outer surface of the glass article with 1 mL of 90 grit SiC particles for 5 seconds at an abrasion pressure, and a ratio of the retained strength at an abrasion pressure of 25 psi to the retained strength at an abrasion pressure of 5 psi is at least about 0.3.

What is claimed is: 
     
         1 . A method comprising:
 forming a glass article comprising a core layer and a cladding layer adjacent to the core layer, the glass article comprising a coefficient of thermal expansion (CTE) mismatch between the core layer and the cladding layer and a ratio of a thickness of the core layer to a thickness of the glass article such that a Knoop scratch threshold of the glass article is at least about 5 N, an indentation threshold of the glass article is at least about 20 N, and a compressive stress of the cladding layer is at most about 500 MPa.   
     
     
         2 . The method of  claim 1 , wherein the ratio of the thickness of the core layer to the thickness of the glass article is at least about 0.8. 
     
     
         3 . The method of  claim 1 , wherein a retained strength of the glass article comprises a strength determined after abrasion of an outer surface of the glass article with 1 mL of 90 grit SiC particles for 5 seconds at an abrasion pressure, and a ratio of the retained strength at an abrasion pressure of 25 psi to the retained strength at an abrasion pressure of 5 psi is at least about 0.3. 
     
     
         4 . The method of  claim 3 , wherein the ratio of the retained strength at the abrasion pressure of 25 psi to the retained strength at the abrasion pressure of 5 psi is at least about 0.75. 
     
     
         5 . The method of any of  claim 1 , wherein the glass article comprises a laminated glass sheet, and the forming the glass article comprises forming the glass article using a fusion draw process. 
     
     
         6 . A glass article comprising:
 a glass core layer comprising from about 50 mol % to about 80 mol % SiO 2 , from about 5 mol % to about 20 mol % Al 2 O 3 , and from about 1 mol % to about 8 mol % MgO; and   a glass cladding layer adjacent to the core layer and comprising from about 60 mol % to about 70 mol % SiO 2 , from about 6 mol % to about 18 mol % Al 2 O 3 , from about 4 mol % to about 21 mol % B 2 O 3 , from about 0.2 mol % to about 5 mol % MgO, and from about 3 mol % to about 12 mol % CaO;   wherein a Knoop scratch threshold of the glass article is at least about 5 N, and an indentation threshold of the glass article is at least about 20 N.   
     
     
         7 . The glass article of  claim 6 , wherein the core layer further comprises from about 3 mol % to about 11 mol % B 2 O 3 . 
     
     
         8 . The glass article of  claim 6 , wherein the core layer further comprises from about 0.01 mol % to about 8 mol % CaO. 
     
     
         9 . The glass article of any of  claim 6 , wherein the core layer further comprises from about 3 mol % to about 7 mol % SrO. 
     
     
         10 . The glass article of any of  claim 6 , wherein the core layer further comprises from about 0.01 mol % to about 0.1 mol % BaO. 
     
     
         11 . The glass article of any of  claim 6 , wherein the cladding layer further comprises from about 0.2 mol % to about 3 mol % SrO. 
     
     
         12 . The glass article of any of  claim 6 , wherein the cladding layer further comprises from about 0.01 mol % to about 2 mol % BaO. 
     
     
         13 . The glass article of any of  claim 6 , wherein the core layer comprises a coefficient of thermal expansion (CTE) of at least about 40×10 −7 ° C. −1 . 
     
     
         14 . The glass article of any of  claim 6 , wherein the cladding layer comprises a CTE of at most about 40×10 −7 ° C. −1 . 
     
     
         15 . The glass article of  claim 13 , wherein the CTE of the core layer and the CTE of the cladding layer differ by at least about 5×10 −7 ° C. −1 . 
     
     
         16 . The glass article of any of  claim 13 , wherein the CTE of the core layer and the CTE of the cladding layer differ by at most about 55×10 −7 ° C. −1 . 
     
     
         17 . The glass article of any of  claim 6 , wherein the cladding layer is substantially free of alkali metal. 
     
     
         18 . The glass article of any of  claim 6 , wherein a thickness of the glass article is about 0.2 mm to about 2 mm, and a ratio of a thickness of the core layer to the thickness of the glass article is at least about 0.8. 
     
     
         19 . The glass article of any of  claim 6 , wherein the core layer comprises a tensile stress, and the cladding layer comprises a compressive stress of at most about 500 MPa.