Glass element with high scratch tolerance
A glass element is provided that is made of a glass having SiO 2 , Al 2 O 3 , B 2 O 3 , and Na 2 O. The glass has a scratch tolerance that when scratches of 1 mm length are introduced using a Knoop diamond indenter which presses upon a surface of the glass with a force of 4 Newton and is displaced along the surface with a traverse speed of 0.4 mm/s, not more than 20% of the scratches have a noticeable width including visible chipping of more than 25 μm. In some embodiments, the glass, after chemical tempering, has sodium ions that are at least partially exchanged for potassium ions so that a compressive stress zone is provided at the surface of the glass. The compressive stress is at least 700 MPa and an exchange depth of alkali ions is at least 25 μm.
1. A glass element comprising:
a glass comprising the following components, in mole percent:
SiO 2
56-70%,
Al 2 O 3
10.5-16%,
B 2 O 3
2.5-9%,
Na 2 O
10-15%,
K 2 O
1-4.5%,
ZrO 2
0.1-2.1%, and
a quotient B 2 O 3 /(Al 2 O 3 +ZrO 2 ) of a content of B 2 O 3 and a total content of Al 2 O 3 and ZrO 2 has a value in a range from 0.18 to 0.55,
wherein the glass has a scratch tolerance prior to chemical tempering that when scratches of 1 mm length are introduced using a Knoop diamond indenter which presses upon a surface of the glass with a force of 4 Newton and is displaced along the surface with a traverse speed of 0.4 mm/s, not more than 20% of the scratches have a noticeable width including visible chipping of more than 25 μm.
2. The glass element as in claim 1 , wherein the scratch tolerance is such that none of the scratches have a crack running into the glass to a depth of more than 50 μm.
3. The glass element as claimed in claim 1 , wherein the glass has a composition comprising the following components, in mole percent:
57-69%
SiO 2 ;
11-15.6%
Al 2 O 3 ;
3-8%
B 2 O 3 ;
11-15%
Na 2 O;
0-5%
MgO;
0.1-1.5%
ZrO 2 ;
0-1.5%
TiO 2 ;
0-0.1%
CeO 2 ;
0-0.3%
SnO 2 ;
0-1.5%
P 2 O 5 ; and
0-1%
of other components, with a content of Li 2 O being
less than 0.05%.
4. The glass element as claimed in claim 1 , wherein the glass has a composition comprising the following components, in mole percent:
59-68%
SiO 2 ;
>12-15.6%
Al 2 O 3 ;
3-8%
B 2 O 3 ;
11-15%
Na 2 O;
0-5%
MgO;
0.1-1.5%
ZrO 2 ;
0-1.5%
TiO 2 ;
0-0.1%
CeO 2 ;
0-0.3%
SnO 2 ;
0-1.5%
P 2 O 5 ;
0-2%
ZnO; and
0-1%
of other components.
5. The glass element as claimed in claim 1 , wherein the glass has a sheet-like shape.
6. The glass element as claimed in claim 1 , wherein the glass is substantially free of coloring components.
7. The glass element as claimed in claim 1 , wherein the glass has a total proportion of 3d transition metals with coloring ionic species that is smaller than 0.1 mol %.
8. The glass element as claimed in claim 1 , wherein the glass has a working point at which it has a viscosity of 10 4 dPa·s at a temperature of less than 1300° C.
9. The glass element as claimed in claim 1 , wherein the glass has a glass transition temperature above 580° C.
10. The glass element as claimed in claim 1 , wherein the quotient B 2 O 3 /(Al 2 O 3 +ZrO 2 ) has a value in a range from 0.2 to 0.5.
11. The glass element as claimed in claim 1 , wherein the quotient B 2 O 3 /(Al 2 O 3 +ZrO 2 ) has a value in a range from 0.22 to 0.47.
12. The glass element as in claim 1 , wherein the glass has a composition comprising the following components, in mole percent:
0-6%
MgO;
0-2.1%
TiO 2 ;
0-0.1%
CeO 2 ;
0-0.3%
SnO 2 ;
0-1.5%
P 2 O 5 ;
0-2%
ZnO;
0-<0.2%
Li 2 O; and
0-2%
of other components, with a content of fluoride of less
than 0.2%.
13. The glass element as in claim 12 , wherein the content of fluoride is less than 0.05%.
14. The glass element as claimed in claim 12 , wherein, in the composition, at least one of the following conditions is met:
a total content of components Al 2 O 3 , ZrO 2 , TiO 2 is in a range from 10.6% to 18.1%;
a total content of components Al 2 O 3 and B 2 O 3 is in a range from 13% to 23%;
a total content of components ZrO 2 and TiO 2 is in a range from 0.1% to 2.1%;
a total content of components Na 2 O and K 2 O is in a range from 11% to 17%;
a content of each of components CaO, SrO, and BaO is not greater than 0.1%, and
a total content of components CaO, SrO, and BaO is not greater than 0.2%.
15. The glass element as claimed in claim 12 , wherein, in the composition, the following condition is met:
a quotient (B 2 O 3 +Al 2 O 3 +ZrO 2 )/(Na 2 O+K 2 O+MgO) of a total content of components B 2 O 3 , Al 2 O 3 , ZrO 2 and a total content of components Na 2 O, K 2 O, MgO has a value in a range from 0.95 to 1.55.
16. The glass element as claimed in claim 1 , wherein the glass, after chemical tempering, has sodium ions that are at least partially exchanged for potassium ions so that a compressive stress zone is provided at the surface of the glass, wherein the compressive stress is at least 700 MPa and an exchange depth of alkali ions is at least 25 μm.
17. The glass element as claimed in claim 16 , wherein the compressive stress zone is at least 750 MPa and the exchange depth of alkali ions is at least 30 μm.
18. The glass element as claimed in claim 16 , wherein the compressive stress zone is greater than 800 MPa and the exchange depth of alkali ions is at least 35 μm.
19. A glass element comprising a glass comprising, in mole percent:
SiO 2
56-70%,
Al 2 O 3
10.5-16%,
B 2 O 3
2.5-9%,
Na 2 O
10-15%,
K 2 O
1-4.5%,
ZrO 2
0.1-2.1%,
a total content of components Al 2 O 3 and B 2 O 3 is in a range from 13% to 23%, and
a total content of components Na 2 O and K 2 O is in a range from 11% to 17%.