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.

1 . A method of making a glass article, the method comprising:
 melting constituents, 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 %; and 
   forming the melted constituents into a glass article.   
     
     
         2 . The method of  claim 1 , wherein 4 mol %≤MgO+CaO+SrO≤Al 2 O 3 . 
     
     
         3 . The method of  claim 1 , wherein the constituents further comprise at least one of SnO 2 , CeO 2 , As 2 O 3 , Sb 2 O 5 , Cl − , and F − . 
     
     
         4 . The method of  claim 1 , wherein the constituents comprise 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 .   
     
     
         5 . The method of  claim 1 , wherein the constituents comprise:
 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.   
     
     
         6 . The method of  claim 5 , wherein the constituents comprise up to 0.2 mol % SnO 2 . 
     
     
         7 . The method of  claim 1 , wherein the forming comprises down-drawing. 
     
     
         8 . The method of  claim 1 , wherein the constituents comprise up to 0.1 mol % ZrO 2 . 
     
     
         9 . The method of  claim 1 , wherein the constituents are free of alkali metal oxide modifiers. 
     
     
         10 . A method of making a glass article, the method comprising:
 melting constituents, 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 %; and 
   forming the melted constituents into a glass article.   
     
     
         11 . The method of  claim 10 , wherein the constituents comprise 4 mol %≤(MgO+CaO+SrO)≤Al 2 O 3 . 
     
     
         12 . The method of  claim 11 , wherein the constituents comprise 4 mol %≤(Li 2 O+Na 2 O+K 2 O+MgO+CaO+SrO)≤Al 2 O 3 . 
     
     
         13 . The method of  claim 10 , wherein the constituents comprise 55 mol %≤SiO 2 ≤64.20 mol %. 
     
     
         14 . The method of  claim 13 , wherein the constituents comprise 20.87 mol %≤B 2 O 3 ≤30 mol %. 
     
     
         15 . The method of  claim 10 , where a majority of the B 2 O 3  of the constituents is in a threefold coordinated state. 
     
     
         16 . The method of  claim 10 , wherein the forming comprises down-drawing. 
     
     
         17 . A method of making a glass article, the method comprising:
 melting constituents, 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 %; and 
   forming the melted constituents into a glass article.   
     
     
         18 . The method of  claim 17 , wherein the constituents comprise 4 mol %≤(Li 2 O+Na 2 O+K 2 O+MgO+CaO+SrO)≤Al 2 O 3 . 
     
     
         19 . The method of  claim 17 , where a majority of the B 2 O 3  of the constituents is in a threefold coordinated state. 
     
     
         20 . The method of  claim 17 , wherein the forming comprises down-drawing. 
     
     
         21 . A method of making a glass article, the method comprising:
 melting constituents, 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 %; and 
   forming the melted constituents into a glass article.   
     
     
         22 . The method of  claim 21 , wherein the constituents comprise 4 mol %≤(Li 2 O+Na 2 O+K 2 O+MgO+CaO+SrO)≤Al 2 O 3 . 
     
     
         23 . The method of  claim 21 , where a majority of the B 2 O 3  of the constituents is in a threefold coordinated state. 
     
     
         24 . The method of  claim 21 , wherein the forming comprises down-drawing.