Crack and scratch resistant glass and enclosures made therefrom
A glass and an enclosure, including windows, cover plates, and substrates for mobile electronic devices comprising the glass. The glass has a crack initiation threshold that is sufficient to withstand direct impact, has a retained strength following abrasion that is greater than soda lime and alkali aluminosilicate glasses, and is resistant to damage when scratched. The enclosure includes cover plates, windows, screens, and casings for mobile electronic devices and information terminal devices.
1. A glass comprising:
at least 58 mol % SiO 2 ;
at least 8 mol % Na 2 O;
5.5-12 mol % B 2 O 3 ; and
Al 2 O 3 ;
wherein a ratio
Al
2
O
3
(
mol
%
)
+
B
2
O
3
(
mol
%
)
∑
modifiers
(
mol
%
)
>
1
,
the modifiers are one or more alkali metal oxide (R 2 O) and one or more alkaline earth oxide (RO);
wherein Al 2 O 3 (mol %)>B 2 O 3 (mol %) and 0.9<R 2 O/Al 2 O 3 <1.3, wherein the glass is substantially free of Li 2 O.
2. The glass of claim 1 , wherein the glass is ion exchanged and has a layer under a compressive stress of at least about 600 MPa, the layer extending from a surface of the glass into the glass to a depth of layer of at least about 30 μm.
3. The glass of claim 2 , wherein the compressive stress is at least about 800 MPa.
4. The glass of claim 2 , wherein the glass has a Vickers crack initiation threshold of at least about 30 kgf.
5. The glass of claim 1 , wherein the glass is defined by the equation
Al
2
O
3
(
mol
%
)
+
B
2
O
3
(
mol
%
)
∑
modifiers
(
mol
%
)
≥
1.45
.
6. The glass of claim 1 , wherein the glass comprises from about 60 to 72 mol % SiO 2 , about 9 mol % to about 17 mol % Al 2 O 3 , and about 8 mol % to about 20 mol % Na 2 O.
7. The glass of claim 1 , wherein the glass comprises at least one of MgO, ZnO, CaO, SrO, and BaO.
8. The glass of claim 1 , wherein the glass comprises 5.5-10 mol % B 2 O 3 .
9. The glass of claim 1 , wherein the glass comprises from 0 mol % to about 4 mol % K 2 O.
10. The glass of claim 1 , wherein the glass is defined by the following equation −5.7 mol %<Σ modifiers−Al 2 O 3 <2.99 mol %.
11. The glass of claim 1 , wherein the glass is defined by the following equation 1.0<R 2 O/Al 2 O 3 <1.3.
12. The glass of claim 1 , wherein the glass has a Young's modulus of less than about 69 GPa.
13. A glass comprising:
at least 58 mol % SiO 2 ;
at least 8 mol % Na 2 O;
2-12 mol % B 2 O 3 ; and
Al 2 O 3 ;
wherein a ratio
Al
2
O
3
(
mol
%
)
+
B
2
O
3
(
mol
%
)
∑
modifiers
(
mol
%
)
>
1
,
the modifiers are one or more alkali metal oxide (R 2 O) and one or more alkaline earth oxide (RO);
wherein 0.9<R 2 O/Al 2 O3<1.3, Al 2 O 3 (mol %)>B 2 O 3 (mol %), and wherein the glass is defined by the following equation −5.7 mol %<Σ modifiers−Al 2 O 3 <2.17 mol %.
14. The glass of claim 13 , wherein the glass is defined by the equation
Al
2
O
3
(
mol
%
)
+
B
2
O
3
(
mol
%
)
∑
modifiers
(
mol
%
)
≥
1.45
.
15. The glass of claim 13 , wherein the glass comprises from about 60 to 72 mol % SiO 2 , about 9 mol % to about 17 mol % Al 2 O 3 , and about 8 mol % to about 20 mol % Na 2 O.
16. The glass of claim 13 , wherein the glass comprises at least one of MgO, ZnO, CaO, SrO, and BaO.
17. The glass of claim 13 , wherein the glass comprises 3-10 mol % B 2 O 3 .
18. The glass of claim 13 , wherein the glass is defined by the following equation 1.0<R 2 O/Al 2 O 3 <1.3.
19. The glass of claim 13 , wherein the glass has a Young's modulus of less than about 69 GPa.
20. A glass comprising:
at least 58 mol % SiO 2 ;
at least 8 mol % Na 2 O;
2-10 mol % B 2 O 3 ;
Al 2 O 3 ; and
wherein a ratio
Al
2
O
3
(
mol
%
)
+
B
2
O
3
(
mol
%
)
∑
modifiers
(
mol
%
)
>
1
,
the modifiers are one or more alkali metal oxide (R 2 O) and one or more alkaline earth oxide (RO);
wherein 0.9<R 2 O/Al 2 O 3 <1.3, and wherein the glass is defined by the following equation −5.7 mol %<Σ modifiers−Al 2 O 3 <2.17 mol %.
21. The glass of claim 20 , wherein the glass is defined by the equation
Al
2
O
3
(
mol
%
)
+
B
2
O
3
(
mol
%
)
∑
modifiers
(
mol
%
)
≥
1.45
.
22. The glass of claim 20 , wherein the glass comprises from about 60 to 72 mol % SiO 2 , about 9 mol % to about 17 mol % Al 2 O 3 , and about 8 mol % to about 20 mol % Na 2 O.
23. The glass of claim 20 , wherein the glass comprises at least one of MgO, ZnO, CaO, SrO, and BaO.
24. The glass of claim 20 , wherein the glass comprises 3-10 mol % B 2 O 3 .
25. The glass of claim 20 , wherein the glass is defined by the following equation 1.0<R 2 O/Al 2 O 3 <1.3.