Ion exchanged, fast cooled glasses
A glass that is ion exchangeable to a depth of at least 20 μm (microns) and has a internal region having a tension of less than or equal to 100 MPa. The glass is quenched or fast cooled from a first temperature above the anneal point of the glass to a second temperature that is below the strain point of the glass. In one embodiment, the glass is a silicate glass, such as an alkali silicate glass, an alkali aluminosilicate glass, an aluminosilicate glass, a borosilicate glass, an alkali aluminogermanate glass, an alkali germanate glass, an alkali gallogermanate glass, and combinations thereof.
1. A glass article, the glass article having an anneal point and a strain point, wherein the glass article is quenched from a first temperature that is greater than the anneal point of the glass article to a second temperature, wherein the second temperature is less than the strain point of the glass article, the glass article comprising: 60-70 mol % SiO 2 ; 6-14 mol % Al 2 O 3 ; 0-15 mol % B 2 O 3 ; 0-2.5 mol % Li 2 O; 0-20 mol % Na 2 O; 0-10 mol % K 2 O; 0-8 mol % MgO; 0-10 mol % CaO; 0-5 mol % ZrO 2 ; 0-1 mol % SnO 2 ; and 0-1 mol % CeO 2 , wherein 12 mol %≦Li 2 O+Na 2 O+K 2 O≦20 mol % and 0 mol %≦MgO+CaO≦10 mol %, wherein the glass article is substantially free of antimony, barium, and arsenic, and wherein the glass article is ion exchangeable.
2. The glass article according to claim 1 , wherein the glass article is ion exchanged and has a central tension of less than about 100 MPa.
3. The glass according to claim 1 , wherein the glass article is quenched from the first temperature to the second temperature at a rate of at least 4° C./s.
4. The glass article according to claim 1 , wherein the glass is substantially free of lithium.
5. The glass article according to claim 1 , wherein the glass article is a glass sheet having a thickness ranging from about 0.1 mm up to about 3 mm.
6. The glass article according to claim 1 , wherein the glass article is a sheet that is down-drawn.
7. The glass article according to claim 1 , wherein the glass article is a cover plate for a portable electronic device.
8. The glass article according to claim 1 , wherein the glass article is ion exchanged.
9. The glass article according to claim 8 , wherein the ion exchanged surface region has a surface compressive stress of at least about 200 MPa.
10. A method of making a silicate glass article, the glass article having an anneal point and a strain point, wherein the glass article has an ion exchanged surface region having a depth of at least 20 μm, the method comprising the steps of:
a. providing a glass article, the glass article comprising: 60-70 mol % SiO 2 ; 6-14 mol % Al 2 O 3 ; 0-15 mol % B 2 O 3 ; 0-2.5 mol % Li 2 O; 0-20 mol % Na 2 O; 0-10 mol % K 2 O; 0-8 mol % MgO; 0-10 mol % CaO; 0-5 mol % ZrO 2 ; 0-1 mol % SnO 2 ; and 0-1 mol % CeO 2 , wherein 12 mol %≦Li 2 O+Na 2 O+K 2 O≦20 mol % and 0 mol %≦MgO+CaO≦10 mol %, wherein the glass article is substantially free of antimony, barium, and arsenic;
b. heating the glass article up to a first temperature that is greater than the anneal point of the glass article;
c. quenching the glass article from the first temperature to a second temperature, wherein the second temperature is less than the strain point of the glass article; and
d. forming an ion exchanged surface layer having a depth of at least 20 μm in the glass article.
11. The method according to claim 10 , wherein the step of quenching the glass article from the first temperature to the second temperature comprises quenching the glass article at a rate of at least 4° C./s from the first temperature to a second temperature.
12. The method according to claim 10 , wherein the step of providing a glass article comprises providing a glass melt.
13. The method according to claim 12 , wherein the step of quenching the glass article from the first temperature to the second temperature comprises down-drawing the glass melt to form a sheet of glass.
14. The method according to claim 10 , wherein the silicate glass is one of an alkali silicate glass, an alkali aluminosilicate glass, an aluminosilicate glass, a borosilicate glass, an alkali aluminogermanate glass, an alkali germanate glass, an alkali gallogermanate glass, and combinations thereof.
15. A method of strengthening a alkali silicate glass without inducing frangibility of the glass article, the method comprising the steps of:
a. providing a glass article, wherein the glass article has an anneal point and a strain point and comprising: 60-70 mol % SiO 2 ; 6-14 mol % Al 2 O 3 ; 0-15 mol % B 2 O 3 ; 0-2.5 mol % Li 2 O; 0-20 mol % Na 2 O; 0-10 mol % K 2 O; 0-8 mol % MgO; 0-10 mol % CaO; 0-5 mol % ZrO 2 ; 0-1 mol % SnO 2 ; and 0-1 mol % CeO 2 , wherein 12 mol %≦Li 2 O+Na 2 O+K 2 O≦20 mol % and 0 mol % MgO+CaO≦10 mol %, wherein the glass article is substantially free of antimony, barium, and arsenic;
b. heating the glass article to a first temperature above the anneal point of the glass, wherein heating the glass article above the anneal point increases the volume of the glass;
c. quenching the glass article from the first temperature to a second temperature below the strain point of the glass article at a predetermined rate and
d. exchanging a plurality of ions of a first alkali metal in the glass article with a plurality of ions second of a second alkali metal, wherein each of the plurality of ions of the second alkali metal has an ionic radius greater than that of each of the plurality of ions of the first alkali metal to create a surface compressive stress profile in the glass article.
16. The method according to claim 11 , wherein the first alkali metal and the second alkali metal are alkali metals other than lithium ions.
17. The method according to claim 15 , wherein the glass article is quenched from the first temperature to the second temperature at a rate of at least 4° C./s.
18. The glass article according to claim 9 , has an ion exchanged surface region having a depth of at least 20 μm.