Fusion formable and steam strengthenable glass compositions with platinum compatibility

Abstract

Glass-based articles that include a compressive stress layer extending from a surface of the glass-based article to a depth of compression are formed by exposing glass-based substrates to water vapor containing environments. The glass-based substrates have compositions selected to be fusion formable, to be steam strengthen able, and to avoid the formation of platinum defects during the forming process. The methods of forming the glass-based articles may include elevated pressures and/or multiple exposures to water vapor containing environments.

What is claimed is: 
     
         1 . A method, comprising:
 exposing a glass-based substrate to a treatment environment with a pressure greater than or equal to 0.1 MPa, a water partial pressure of greater than or equal to 0.05 MPa, and a temperature greater than 85° C. to form a glass-based article, wherein the glass-based substrate comprises:
 SiO 2 , 
 Al 2 O 3 , 
 K 2 O, 
 R 2 O/Al 2 O 3  in an amount that is less than or equal to 1.4, wherein R 2 O is the total amount of monovalent metal oxides, 
 greater than or equal to 3.5 mol % to less than or equal to 6.0 mol % P 2 O 5 , and 
 greater than or equal to 2.0 mol % to less than or equal to 5.0 mol % Li 2 O, 
   wherein the glass-based article comprises:
 a compressive stress layer extending from a surface of the glass-based article to a depth of compression, the compressive stress layer comprising a compressive stress greater than or equal to 25 MPa, 
 a hydrogen-containing layer extending from the surface of the glass-based article to a depth of layer, a hydrogen concentration of the hydrogen-containing layer decreases from a maximum hydrogen concentration to the depth of layer, and 
 the depth of layer is greater than 5 μm. 
   
     
     
         2 . The method of  claim 1 , wherein the treatment environment is a saturated steam environment. 
     
     
         3 . The method of  claim 1 , wherein the treatment environment has a pressure greater than or equal to 1 MPa. 
     
     
         4 . The method of  claim 1 , wherein the treatment environment has a temperature greater than or equal to 150° C. 
     
     
         5 . The method of  claim 1 , further comprising producing the glass-based substrate by a fusion forming process. 
     
     
         6 . The method of  claim 1 , wherein the glass-based substrate is not subjected to an ion-exchange treatment with an alkali ion source. 
     
     
         7 . The method of  claim 1 , wherein the glass-based substrate further comprises B 2 O 3 . 
     
     
         8 . The method of  claim 1 , wherein the glass-based substrate further comprises Na 2 O. 
     
     
         9 . The method of  claim 1 , wherein the glass-based substrate further comprises SnO 2 . 
     
     
         10 . The method of  claim 1 , wherein the glass-based substrate has an average field strength of alkali modifiers that is less than or equal to 0.18. 
     
     
         11 . The method of  claim 1 , wherein the glass-based substrate comprises:
 greater than or equal to 55.0 mol % to less than or equal to 65.0 mol % SiO 2 ,   greater than or equal to 10.0 mol % to less than or equal to 15.0 mol % Al 2 O 3 ,   greater than or equal to 0 mol % to less than or equal to 10.0 mol % B 2 O 3 , and   greater than or equal to 6.0 mol % to less than or equal to 15.0 mol % K2O.   
     
     
         12 . The method of  claim 1 , wherein the glass-based substrate comprises greater than or equal to 4.5 mol % to less than or equal to 5.5 mol % P 2 O 5 . 
     
     
         13 . The method of  claim 1 , wherein the glass-based substrate comprises greater than 0 mol % to less than or equal to 3.0 mol % B 2 O 3 . 
     
     
         14 . The method of  claim 1 , wherein the glass-based substrate comprises a fusion line. 
     
     
         15 . The method of  claim 1 , wherein the glass-based substrate comprises less than 1 globular chain platinum defect per pound. 
     
     
         16 . The method of  claim 1 , wherein the glass-based substrate has a zircon breakdown viscosity of less than or equal to 35 kP. 
     
     
         17 . The method of  claim 1 , wherein the glass-based substrate has a liquidus viscosity of greater than or equal to 100 kP. 
     
     
         18 . The method of  claim 1 , wherein the glass-based article has a substantially haze-free appearance. 
     
     
         19 . The method of  claim 1 , wherein the depth of compression is greater than 5 μm. 
     
     
         20 . The method of  claim 1 , wherein the compressive stress layer comprises a compressive stress greater than or equal to 200 MPa.