Fast ion exchangeable glasses with high indentation threshold

Abstract

Alkali aluminosilicate glasses that are ion exchangeable to high compressive stresses, have fast ion exchange kinetics, and high intrinsic damage resistance. The glasses achieve all of the above desired properties either with only small amounts of P2O5 (<1 mol %) or without addition of any P2O5.

1 . A glass, the glass comprising:
 from 50 mol % to 72 mol % SiO 2 ;   from 12 mol % to 22 mol % Al 2 O 3 ;   up to 6.5 mol % B 2 O 3 ;   up to 1 mol % P 2 O 5 ;   from 11 mol % to 21 mol % Na 2 O;   from 1.42 mol % to 3.21 mol % K 2 O;   up to 4 mol % MgO;   up to 5 mol % ZnO; and   up to 2 mol % CaO, wherein   Na 2 O+K 2 O—Al 2 O 3 ≤2.0 mol, and   B 2 O 3 —(Na 2 O+K 2 O—Al 2 O 3 )>1 mol %.   
     
     
         2 . The glass of  claim 1 , wherein the glass comprises from 1.42 mol % to 2.19 mol % K 2 O. 
     
     
         3 . The glass of  claim 1 , wherein the glass is substantially free of at least one of TiO 2 , P 2 O 5  and Li 2 O. 
     
     
         4 . The glass of  claim 1 , wherein the glass is substantially free of Li 2 O. 
     
     
         5 . The glass of  claim 1 , wherein 56 mol %≤SiO 2 +B 2 O 3 ≤75 mol %. 
     
     
         6 . The glass of  claim 1 , wherein the glass comprises from 1.49 mol % to 2.01 mol % K 2 O. 
     
     
         7 . The glass of  claim 1 , wherein the glass is ion exchanged and has a Vickers crack indentation threshold of at least 9.5 kgf. 
     
     
         8 . The glass of  claim 1 , wherein the glass has a layer under compressive stress CS of greater than 500 MPa, the layer extending from a surface of the glass to a depth of layer DOL, wherein CS·DOL≥44000 MPa·μm. 
     
     
         9 . The glass of  claim 1 , wherein the glass is substantially free of As 2 O 3  and Sb 2 O 5 . 
     
     
         10 . The glass of  claim 1 , wherein the glass has a liquidus viscosity of at least 100 kpoise. 
     
     
         11 . A glass comprising:
 from 55 mol % to 62 mol % SiO 2 ;   from 16 mol % to 20 mol % Al 2 O 3 ;   from 4 mol % to 6.5 mol % B 2 O 3 ;   from 14 mol % to 18 mol % Na 2 O;   from 1.42 mol % to 3.21 mol % K 2 O;   up to 0.5 mol % MgO;   up to 0.5 mol % ZnO; and   up to 0.5 mol % CaO, wherein   the glass is substantially free of P 2 O 5 ,   Na 2 O+K 2 O—Al 2 O 3 ≤0.5 mol %, and   B 2 O 3 —(Na 2 O+K 2 O—Al 2 O 3 )>4 mol %.   
     
     
         12 . The glass of  claim 11 , wherein the glass comprises from 1.42 mol % to 2.19 mol % K 2 O. 
     
     
         13 . The glass of  claim 11 , wherein the glass comprises from 1.49 mol % to 2.01 mol % K 2 O. 
     
     
         14 . The glass of  claim 11 , wherein the glass is substantially free of at least one of Li 2 O and TiO 2 . 
     
     
         15 . The glass of  claim 11 , wherein 56 mol %≤SiO 2 +B 2 O 3 ≤70 mol %. 
     
     
         16 . The glass of  claim 11 , wherein 0 mol %≤Σ[R′O]≤0.5 mol %, where R′ is at least one of Ca, Mg, and Zn. 
     
     
         17 . The glass of  claim 11 , wherein the glass is substantially free of As 2 O 3  and Sb 2 O 3 . 
     
     
         18 . The glass of  claim 11 , wherein the glass has a liquidus viscosity of at least 100 kpoise. 
     
     
         19 . The glass of  claim 11 , wherein the glass is ion exchanged and has a Vickers crack indentation threshold of at least 9.5 kgf. 
     
     
         20 . The glass of  claim 11 , wherein the glass has a layer under compressive stress CS of greater than 500 MPa, the layer extending from a surface of the glass to a depth of layer DOL, wherein CS·DOL≥44000 MPa·μm.