Transparent β-quartz glass-ceramics with low lithium content

Patent metadata

Field	Value
Publication number	US-11352290-B2
Application number	US-201816620307-A
Country	US
Kind code	B2
Filing date	Jun 6, 2018
Priority date	Jun 7, 2017
Publication date	Jun 7, 2022
Grant date	Jun 7, 2022

Abstract

The present application provides transparent glass-ceramics of β-quartz of composition containing a small content of lithium, articles constituted at least in part of said glass-ceramics, glasses precursors of said glass-ceramics, and also a method of preparing said articles. Said glass-ceramics have a composition, free of arsenic oxide and antimony oxide, except for inevitable traces, expressed as percentages by weight of oxides, containing: 62% to 68% of SiO2; 17% to 21% of AI2O3; 1% to <2% of Li2O; 1% to 4% of MgO; 1% to 6% of ZnO; 0 to 4% of BaO; 0 to 4% of SrO; 0 to 1% of CaO; 1% to 5% of TiO2; 0 to 2% of ZrO2; 0 to 1% of Na2O; 0 to 1% of K2O; with Na2O+K2O+BaO+SrO+CaO<6%; optionally up to 2% of at least one fining agent comprising SnO2; and optionally up to 2% of at least one coloring agent.

First claim

The invention claimed is:

1. A transparent glass-ceramic containing a solid solution of β-quartz as its main crystalline phase, the composition of which, free of arsenic oxide and antimony oxide, except for inevitable traces, expressed as percentages by weight of oxides, comprises:
62% to 68% of SiO 2 ;
17% to 21% of Al 2 O 3 ;
1% to <2% of Li 2 O;
1% to 4% of MgO;
1% to 6% of ZnO;
0 to 4% of BaO;
0 to 4% of SrO;
0 to 1% of CaO;
1% to 5% of TiO 2 ;
0 to 2% of ZrO 2 ;
0 to 1% of Na 2 O;
0 to 1% of K 2 O;
with Na 2 O+K 2 O+BaO+SrO+CaO≤6%;
optionally up to 2% of at least one fining agent comprising SnO 2 ; and
0.01% to 2% of at least one coloring agent, wherein the coloring agent comprises 0.005% to 0.1% V 2 O 5 mixed with at least one other coloring agent selected from CoO, Cr 2 O 3 , and Fe 2 O 3 ;
wherein the transparent glass ceramic comprises a coefficient of thermal expansion CTE 25° C.-300° C. of less than 20·10 −7 K −1 ; and
the transparent glass ceramic has a thickness from 1 mm to 8 mm and an integrated transmission of less than 10% while maintaining transmission at 625 nm greater than 1% and at 950 nm from 50% to 75%.

2. The glass-ceramic according to claim 1 , wherein the composition comprises 1% to 1.9% of Li 2 O.

3. The glass-ceramic according to claim 1 , wherein the composition comprises 17.5% to 19% of Al 2 O 3 .

4. The glass-ceramic according to claim 1 wherein the composition comprises 1% to 3% of MgO.

5. The glass-ceramic according to claim 1 , wherein the composition comprises 1% to 4% of ZnO.

6. The glass-ceramic according to claim 1 , wherein the composition comprises ZrO 2 .

7. The glass-ceramic according to claim 1 , wherein the composition comprises 0.05% to 0.6% of SnO 2 .

8. An article constituted, at least in part, of a glass-ceramic according to claim 1 .

9. A method of preparing an article constituted, at least in part, of a glass-ceramic containing a solid solution of β-quartz as its main crystalline phase, comprising in succession:
melting a charge of raw materials able to vitrify, followed by fining the resulting molten glass;
cooling the resulting fined molten glass and simultaneously shaping it to the shape desired for the intended article; and
applying ceramming heat treatment to said shaped glass;
wherein said charge has a composition that makes it possible to obtain the transparent glass-ceramic, the composition of which, free of arsenic oxide and antimony oxide, except for inevitable traces, expressed as percentages by weight of oxides, comprises:
62% to 68% of SiO 2 ;
17% to 21% of Al 2 O 3 ;
1% to <2% of Li 2 O;
1% to 4% of MgO;
1% to 6% of ZnO;
0 to 4% of BaO;
0 to 4% of SrO;
0 to 1% of CaO;
1% to 5% of TiO 2 ;
0 to 2% of ZrO 2 ;
0 to 1% of Na 2 O;
0 to 1% of K 2 O;
with Na 2 O+K 2 O+BaO+SrO+CaO≤6%;
0 to 2% of at least one fining agent comprising SnO 2 ; and
0.01% to 2% of at least one coloring agent, wherein the coloring agent comprises 0.005% to 0.1% V 2 O 5 mixed with at least one other coloring agent selected from CoO, Cr 2 O 3 , and Fe 2 O 3 ,
wherein the transparent glass ceramic comprises a coefficient of thermal expansion CTE 25° C.-300° C. of less than 20·10 −7 K −1 ,
the transparent glass ceramic having a thickness from 1 mm to 8 mm and an integrated transmission of less than 10% while maintaining transmission at 625 nm greater than 1% and at 950 nm from 50% to 75%.

10. The method according to claim 9 , wherein said charge of raw materials able to vitrify, free of As 2 O 3 and Sb 2 O 3 , except for inevitable traces, contains SnO 2 as fining agent.

11. The method of claim 10 , wherein the charge of raw materials able to vitrify, free of As 2 O 3 and Sb 2 O 3 , except for inevitable traces, comprises 0.05% to 0.6% of SnO 2 .

12. The glass-ceramic according to claim 2 , wherein the composition comprises 1.5% to 1.9% of Li 2 O.

13. The glass-ceramic of claim 5 , wherein the composition comprises 3% to 4% of ZnO.

14. The glass-ceramic according to claim 6 , wherein the composition 0.5% to 2% of ZrO 2 .

15. The glass-ceramic according to claim 6 , wherein the composition 1% to 2% of ZrO 2 .

16. The glass-ceramic according to claim 7 , wherein the composition comprises 0.15% to 0.4% of SnO 2 .

Assignees

• Eurokera

Inventors

• Comte Marie
• Ogier Thiphaine
• Lehuede Philippe

Classifications

• C03C3/087 Primary

  containing calcium oxide, e.g. common sheet or container glass · CPC title

• C03C3/085

  containing an oxide of a divalent metal · CPC title

• C03C10/0027

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

• C03B32/02

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

• C03C4/02

  for coloured glass · CPC title