Transparent lithium glass-ceramic material, production and use thereof

Patent metadata

Field	Value
Publication number	US-9862633-B2
Application number	US-201514982502-A
Country	US
Kind code	B2
Filing date	Dec 29, 2015
Priority date	Jul 17, 2010
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A lithium-containing, transparent glass-ceramic material is provided. The material has low thermal expansion and has an amorphous, lithium-depleted, vitreous surface zone. The zone is at least 50 nm thick on all sides and encloses a crystalline interior, which has high transmission. The material includes a transition region connecting the zone and the interior.

First claim

What is claimed is:

1. A method for producing a glass-ceramic material, comprising:
supporting a starting glass containing nucleating agents in a kiln on a support plate, the support plate having a contact side in contact with the starting glass including at least one supply/removal line;
inducing a defined air moisture content in the kiln via the at least one supply/removal line;
subjecting the starting glass to a nucleation temperature in the range from 700 to 810° C. for a residence time between 3 and 120 minutes to form glass with nuclei;
heating the glass with nuclei from the nucleation temperature to a first ceramicization temperature of 810 to 880° C. at a heating rate of 0.1 to 5.0 K/min to form at least partially ceramicized glass;
heating the at least partially ceramicized glass from the first ceramicization temperature to a second ceramicization temperature of 880 and 970° C. and holding at the second ceramicization temperature, after heating, for between 1 and 45 minutes to form the glass-ceramic material; and
cooling the glass-ceramic material from the second ceramicization temperature to below 600° C. at a cooling rate of at least 5 K/minute, wherein the glass-ceramic material has a vitreous surface zone and a crystalline interior region.

2. The method of claim 1 , further comprising maintaining, during nucleation and ceramicization, a temperature difference between a top face and a bottom face of the starting glass to be ceramicized of 10 K.

3. The method of claim 2 , wherein the temperature difference is less than 3 K.

4. The method of claim 1 , wherein the cooling rate is not more than 100 K/minute.

5. The method of claim 1 , wherein the defined air moisture content is not more than 10% by volume.

6. The method of claim 1 , wherein the kiln is an electrically heated tunnel kiln.

7. The method of claim 1 , wherein the contact side of the support plate has a surface roughness of 5 μm to 200 μm.

8. The method of claim 1 , wherein the contact side of the support plate has support studs.

9. The method of claim 8 , wherein the support studs have a diameter of 0.5 mm to 100 mm and a distance of center points from one stud to another of 1 mm to 100 mm.

10. The method of claim 1 , wherein the contact side of the support plate comprises grooves.

11. The method of claim 10 , wherein the grooves have a width of 0.1 mm to 20 mm, a depth of 0.05 mm to 2 mm, and a distance from one another of 1 cm to 15 cm.

12. The method of claim 1 , wherein the support plate comprises through-holes.

13. The method of claim 12 , wherein the through-holes have a diameter of 3 mm to 20 mm and a distance of center points from one another of 1 cm to 20 cm.

14. The method of claim 1 , wherein the support plate comprises a porous material.

15. The method of claim 1 , wherein the support plate comprises a parting layer selected from the group consisting of Al 2 O 3 , SnO 2 , TiO 2 , TiAln, SiN, BN, SiO 2 , ZrO 2 , Fe oxide, MgO, Mg silicate, calcium carbonate, Au, Pt, Rh, and combinations thereof.

16. The method of claim 1 , wherein the vitreous surface zone has a consistent thickness on all sides.

17. The method of claim 1 , wherein the vitreous surface zone is not more than 10% by volume of crystals.

18. The method of claim 1 , wherein the vitreous surface zone is not more than 1% by volume of crystals.

19. The method of claim 1 , wherein the crystalline interior region is at least 70% by volume of crystals.

20. The method of claim 1 , wherein the crystalline interior region is at least 90% by volume of crystals.

21. The method of claim 2 , wherein the temperature difference is less than 10 K.

Assignees

• Schott Ag

Inventors

• Gabel Falk
• Becker Otmar
• Glasenapp Michael
• Ortmann Jan-Peter
• Grewer Petra
• Luther Veit
• Striegler Harald
• Wennemann Dietmar
• Schuler Thomas
• Johansson Thoralf
• Goetz Helga
• Bug Michael
• Siebenhaar Guenther
• Hahn Gerhard
• Schroeder Friedrich-Georg

Classifications

• C03B32/02 Primary

  Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles {(C03B27/012 takes precedence)} · CPC title

• C03C10/0036

  containing SiO2, Al2O3 and a divalent metal oxide as main constituents · CPC title

• C03C10/0027

  containing SiO2, Al2O3, Li2O as main constituents · CPC title

• Y10T428/315

  Surface modified glass [e.g., tempered, strengthened, etc.] · CPC title

• Y02P40/57

  Improving the yield, e-g- reduction of reject rates · CPC title