Alkali-doped and alkali-free boroaluminosilicate glass

Abstract

Alkali-doped boroaluminosilicate glasses are provided. The glasses include the network formers SiO2, B2O3, and Al2O3. The glass may, in some embodiments, have a Young's modulus of less than about 65 GPa and/or a coefficient of thermal expansion of less than about 40×10−7/° C. The glass may be used as a cover glass for electronic devices, a color filter substrate, a thin film transistor substrate, or an outer clad layer for a glass laminate.

The invention claimed is: 
     
       1. A glass, the glass comprising:
 about 50 mol % to about 70 mol % SiO 2 ; 
 about 6 mol % to about 10 mol % Al 2 O 3 ; 
 about 18 mol % to about 30 mol % B 2 O 3 ; 
 up to about 5 mol % MgO; 
 up to about 10 mol % CaO; 
 up to about 5 mol % SrO; and 
 0.01 mol % to about 0.5 mol % Fe 2 O 3 , 
 wherein MgO+CaO+SrO≤Al 2 O 3 , and a sum of alkali metal oxide modifiers is less than or equal to about 1 mol %. 
 
     
     
       2. The glass of  claim 1 , wherein 4 mol %≤MgO+CaO+SrO≤Al 2 O 3 . 
     
     
       3. The glass of  claim 1 , wherein the glass has a Young's modulus of less than about 65 GPa. 
     
     
       4. The glass of  claim 3 , wherein the Young's modulus is less than about 60 GPa. 
     
     
       5. The glass of  claim 1 , wherein the glass has a coefficient of thermal expansion of less than about 40×10 −7 /° C. 
     
     
       6. The glass of  claim 5 , wherein the coefficient of thermal expansion is less than about 35×10 −7 /° C. 
     
     
       7. The glass of  claim 1 , wherein the glass further comprises at least one of SnO 2 , CeO 2 , As 2 O 3 , Sb 2 O 5 , Cl − , and F − . 
     
     
       8. The glass of  claim 1 , wherein the glass comprises at least one of:
 up to about 0.7 mol % SnO 2 ; 
 up to about 0.7 mol % CeO 2 ; 
 up to about 0.5 mol % As 2 O 3 ; and 
 up to about 0.5 mol % Sb 2 O 3 . 
 
     
     
       9. The glass of  claim 1 , wherein the glass comprises:
 about 55 mol % to about 70 mol % SiO 2 ; 
 greater than 6 mol % to about 10 mol % Al 2 O 3 ; 
 about 18 mol % to about 30 mol % B 2 O 3 ; 
 up to about 3 mol % MgO; 
 up to about 10 mol % CaO; and 
 up to about 3 mol % SrO. 
 
     
     
       10. The glass of  claim 9 , wherein the glass comprises up to about 0.2 mol % SnO 2 . 
     
     
       11. The glass of  claim 10 , wherein the glass forms a clad layer in a glass laminate, the glass laminate comprising a core glass and having a coefficient of thermal expansion that is greater than a coefficient of thermal expansion of the clad layer. 
     
     
       12. The glass of  claim 11 , wherein the clad layer is under a compressive stress of at least about 40 MPa. 
     
     
       13. The glass of  claim 1 , wherein the glass has a liquidus viscosity of at least 100 kpoise. 
     
     
       14. The glass of  claim 1 , wherein the glass is downdrawable. 
     
     
       15. The glass of  claim 1 , wherein the glass comprises up to about 0.1 mol % ZrO 2 . 
     
     
       16. The glass of  claim 1 , wherein the glass is free of alkali metal oxide modifiers. 
     
     
       17. The glass of  claim 1 , wherein the glass has a Knoop scratch threshold of at least 15 N. 
     
     
       18. The glass of  claim 17 , wherein the glass has a Knoop scratch threshold of at least 20 N. 
     
     
       19. The glass of  claim 1 , wherein the glass forms at least a portion of a color filter substrate, a thin film transistor substrate, a cover glass, or a touch interface. 
     
     
       20. The glass of  claim 1 , wherein the glass comprises 0 mol % BaO. 
     
     
       21. A glass, comprising:
 55 mol %≤SiO 2 ≤70 mol %;   6 mol %≤Al 2 O 3 ≤10 mol %;   18 mol %≤B 2 O 3 ≤30 mol %;   0 mol %<MgO≤5 mol %;   0 mol %<CaO≤12 mol %;   0 mol %<SrO, wherein 4 mol %≤(MgO+CaO+SrO)≤(Al 2 O 3 +1 mol %); and   0 mol %≤(Li 2 O+Na 2 O+K 2 O)≤0.1 mol %.    
     
     
       22. The glass of claim 21, wherein 4 mol %≤(MgO+CaO+SrO)≤Al 2 O 3 .  
     
     
       23. The glass of claim 22, wherein 4 mol %≤(Li 2 O+Na 2 O+K 2 O+MgO+CaO+SrO)≤Al 2 O 3 .  
     
     
       24. The glass of claim 21, wherein 55 mol %≤SiO 2 ≤64.20 mol %.  
     
     
       25. The glass of claim 24, wherein 20.87 mol %≤B 2 O 3 ≤30 mol %.  
     
     
       26. The glass of claim 21, where a majority of the B 2 O 3  in the glass is in a threefold coordinated state.  
     
     
       27. A glass, comprising:
 55 mol %≤SiO 2 ≤70 mol %;   6 mol %≤Al 2 O 3 ≤10 mol %;   20.87 mol %≤B 2 O 3 ≤30 mol %;   4 mol %≤(MgO+CaO+SrO)≤Al 2 O 3 ; and   0 mol %≤(Li 2 O+Na 2 O+K 2 O)≤0.1 mol %.    
     
     
       28. The glass of claim 27, wherein 4 mol %≤(Li 2 O+Na 2 O+K 2 O+MgO+CaO+SrO)≤Al 2 O 3 .  
     
     
       29. The glass of claim 27, where a majority of the B 2 O 3  in the glass is in a threefold coordinated state.  
     
     
       30. A glass, comprising:
 55 mol %≤SiO 2 ≤64.20 mol %;   6 mol %≤Al 2 O 3 ≤10 mol %;   18 mol %≤B 2 O 3 ≤30 mol %;   4 mol %≤(MgO+CaO+SrO)≤Al 2 O 3 ; and   0 mol %≤(Li 2 O+Na 2 O+K 2 O)≤0.1 mol %.    
     
     
       31. The glass of claim 30, wherein 4 mol %≤(Li 2 O+Na 2 O+K 2 O+MgO+CaO+SrO)≤Al 2 O 3 .  
     
     
       32. The glass of claim 30, where a majority of the B 2 O 3  in the glass is in a threefold coordinated state.