Ion exchangeable glass with high compressive stress
An aluminosilicate glass article having a high compressive stress layer. The glass article comprises at least about 50 mol % SiO 2 and at least about 11 mol % Na 2 O, and has a layer under a compressive stress of at least about 900 MPa and the depth of layer that extends at least about 30 μm from the surface of the glass article into the glass. A method of making such a glass article is also provided.
1. A glass article having a surface and a layer under compressive stress extending from the surface to a depth of layer wherein the compressive stress CS is at least about 900 Mpa and the depth of layer DOL is at least about 30 μm, wherein the glass article comprises:
at least about 50 mol % SiO 2 ;
from about 7 mol % to about 26 mol % Al 2 O 3 ;
from about 11 mol % to about 25 mol % Na 2 O;
from 0 mol % to about 9 mol % B 2 O 3 ;
from 0 mol % to 2.5 mol % K 2 O;
from 0 mol % to about 8.5 mol % MgO; and
from 0 mol % to 1.5 mol % CaO;
wherein the glass article exhibits a CS criterion defined by the equation −340+27.1*Al 2 O 3 −28.7*B 2 O 3 +15.6*Na 2 O−61.4*K 2 O+8.1*(MgO+ZnO)≧40 mol % and a compensation criterion defined by the equation 0.7 mol %≦Na 2 O+K 2 O−Al 2 O 3 −MgO−ZnO≦2 mol %.
2. The glass article of claim 1 , wherein the compensation criterion is 1.0 mol %≦Na 2 O+K 2 O−Al 2 O 3 −MgO−ZnO≦2 mol %.
3. The glass article of claim 1 , wherein the CS criterion defined by the equation −340+27.1*Al 2 O 3 −28.7*B 2 O 3 +15.6*Na 2 O −61.4*K 2 O+8.1*(MgO+ZnO)≧80 mol %.
4. The glass article of claim 3 , wherein the CS criterion defined by the equation −340+27.1*Al 2 O 3 −28.7*B 2 O 3 +15.6*Na 2 O−61.4*K 2 O +8.1*(MgO+ZnO)≧100 mol %.
5. The glass article of claim 1 , wherein the glass article further comprises 0-0.1 mol % of one or more of ZrO 2 , TiO 2 , Fe 2 O 3 , Cr 2 O 3 , Co2O 3 , or V 2 O 3 .
6. The glass article of claim 1 , wherein the glass article is substantially free of Li 2 O.
7. The glass article of claim 1 , wherein the glass article further comprises at least one fining agent selected from the group consisting of F, Cl, Br, I, As 2 O 3 , Sb 2 O 3 , CeO 2 , SnO 2 , and combinations thereof.
8. The glass article of claim 1 , wherein the glass article has a thickness of up to about 1 mm.
9. The glass article of claim 1 , wherein the glass article exhibits a load to failure of at least about 300 kgf.
10. The glass article of claim 1 , wherein the DOL is at least about 40 μm.
11. The glass article of claim 1 , wherein the CS is at least 1000 MPa.
12. The glass article of claim 1 , wherein SiO 2 +Al 2 O 3 +B 2 O 3 +Na 2 O +K 2 O+MgO+ZnO≧95 mol %.
13. The glass article of claim 1 , wherein Na 2 O+Al 2 O 3 +MgO+ZnO>25 mol %.
14. The glass article of claim 1 , wherein the glass comprises greater than 0 to 8.5 mol % MgO.
15. The glass article of claim 1 , wherein the glass comprises 0-0.1 mol % ZrO2.