Chemically tempered glass
Chemically tempered lithium aluminosilicate glasses and methods of tempering are provided. The method allows fast tempering at moderate temperatures, which leads to a deep zone of surface tension with a high level of surface tension.
1 . A chemically tempered glass article having a thickness less than 4 mm, comprising:
a lithium aluminosilicate glass comprising SiO 2 , Al 2 O 3 , 4.6 to 5.4% by weight Li 2 O, and 8.1 to 9.7% by weight Na 2 O,
wherein the glass has a chemical tempered zone of compressive stress at a surface, the zone extending to a depth of at least 50 micrometers into the glass,
wherein, in the zone, lithium ions have been at least partially exchanged by alkali ions in one or more alkali-containing salt melts for a period of not more than 8 hours at a temperature that did not exceed 420° C., and
wherein the zone exhibits a surface tension of at least 600 MPa.
2 . The chemically tempered glass article of claim 1 , wherein the glass article is a glass sheet.
3 . The chemically tempered glass article of claim 1 , wherein the depth is at least 80 micrometers and the surface tension is at least 800 MPa.
4 . The chemically tempered glass article of claim 1 , wherein the glass comprises:
58 to 65% by weight of SiO 2 ;
16 to 20% by weight of Al 2 O 3 ;
0.1 to 1% by weight of B 2 O 3 ;
0.2 to 2.0% by weight of CaO; and
2.5 to 5.0% by weight of ZrO 2 .
5 . The chemically tempered glass article of claim 4 , wherein the glass comprises 0.05 to 1.0% by weight of K 2 O.
6 . The chemically tempered glass article of claim 4 , wherein the glass comprises a total proportion of SnO 2 , CeO 2 , P 2 O 5 , and ZnO from 0 to 2.5% by weight.
7 . The chemically tempered glass article of claim 4 , wherein the glass comprises:
60 to 62% by weight of SiO 2 ;
17.5 to 19.5% by weight of Al 2 O 3 ;
0.5 to 0.7% by weight of B 2 O 3 ;
4.8 to 5.2% by weight of Li 2 O;
8.5 to 9.5% by weight of Na 2 O;
0.2 to 0.5% by weight of K 2 O;
0.5 to 1.2% by weight of CaO;
3.2 to 3.8% by weight of ZrO 2 ; and
one or more of the components selected from the group consisting of SnO 2 , CeO 2 , P 2 O 5 , and ZnO in a total proportion from 0.25 to 1.6% by weight.
8 . The chemically tempered glass article of claim 1 , wherein the glass article is suitable as a cover glass for a device selected from the group consisting of a mobile communication device, a digital camera, a digital photo frame, a personal digital assistant (PDA), a solar energy device, and a touch panel display.
9 . The chemically tempered glass article of claim 1 , wherein the glass article is suitable as a bullet-proof glazing for ground vehicle windows or high speed train windows.
10 . The chemically tempered glass article of claim 1 , wherein the one or more alkali-containing salt melts comprises a first alkali salt melt that comprises NaNO 3 and a second alkali salt melt that comprises KNO 3 .
11 . The chemically tempered glass article of claim 1 , wherein the one or more alkali-containing salt melts comprise a first melt comprising a blend of sodium and potassium and a second melt comprising a blend of sodium and potassium.
12 . A chemically tempered glass article having a thickness less than 4 mm, comprising:
a lithium aluminosilicate glass comprising SiO 2 , Al 2 O 3 , 4.6 to 5.4% by weight Li 2 O, and 8.1 to 9.7% by weight Na 2 O,
wherein the glass has a chemical tempered zone of compressive stress at a surface, the zone extending to a depth of at least 80 micrometers into the glass,
wherein, in the zone, lithium ions have been at least partially exchanged by alkali ions in one or more alkali-containing salt melts, and
wherein the zone exhibits a surface tension of at least 800 MPa.
13 . The chemically tempered glass article of claim 12 , wherein the one or more alkali-containing salt melts comprises a first alkali salt melt that comprises NaNO 3 and a second alkali salt melt that comprises KNO 3 .
14 . The chemically tempered glass article of claim 12 , wherein the one or more alkali-containing salt melts comprise a first melt comprising a blend of sodium and potassium and a second melt comprising a blend of sodium and potassium.
15 . A chemically tempered glass article having a thickness less than 4 mm, comprising:
a lithium aluminosilicate glass comprising SiO 2 , Al 2 O 3 , 4.6 to 5.4% by weight Li 2 O, and 8.1 to 9.7% by weight Na 2 O,
wherein the glass has a chemical tempered zone of compressive stress at a surface, the zone extending to a depth of at least 80 micrometers into the glass,
wherein, in the zone, lithium ions have been at least partially exchanged by alkali ions in one or more alkali-containing salt melts comprising a first melt comprising a blend of sodium and potassium and a second melt comprising a blend of sodium and potassium, and
wherein the zone exhibits a surface tension of at least 800 MPa.