Non-opaque arsenic-free beta-spodumene glass ceramic exhibiting brown-grey coloration

Patent metadata

Field	Value
Publication number	US-9593040-B2
Application number	US-201414193868-A
Country	US
Kind code	B2
Filing date	Feb 28, 2014
Priority date	Feb 28, 2013
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

Methods, compositions, and articles provide for LAS-type glass-ceramics having specific thermo-mechanical, optical and coloration characteristics to yield generally brown-grey products. The glass-ceramic materials may include as colorants iron oxide, vanadium oxide, chromium oxide, cobalt oxide, nickel oxide and/or cerium oxide.

First claim

The invention claimed is:

1. A lithium aluminosilicate glass-ceramic, comprising (in weight %):
60-72% SiO 2 , 18-23% Al 2 O 3 , and 2.5-4.5% Li 2 O; and
0.05-0.20% V 2 O 5 , 0.15-0.30% Fe 2 O 3 , 0.015-0.030% Cr 2 O 3 , 0-0.05% CoO, 0-0.3% NiO, and 0-0.2% CeO 2 ; and
beta-spodumene as a predominant crystalline phase, wherein the glass-ceramic exhibits a brown-grey color with an optical transmittance for a wavelength of 625 nm of greater than 2.0% as measured using an illuminant D65, 2° observer test on 4 mm thick glass-ceramic.

2. The glass-ceramic of claim 1 , wherein a lightness L* thereof is between about 15-40, measured in reflection using an illuminant D65, 10° observer test.

3. The glass-ceramic of claim 1 , wherein at least one of:
a green-red hue (a*) of the glass-ceramic is one of: (i) between about −3 to +4; (ii) 0 to +4; (iii) +0 to +3; and (iv) +0 to +2,
a blue-yellow hue (b*) of the glass-ceramic is one of: (i) between about −10 to +4; (ii) −2 to +4; (iii) −1 to +3; and (iv) 0 to +2, and
said hue is measured using an illuminant D65, 10° observer test.

4. The glass-ceramic of claim 1 , wherein a coefficient of thermal expansion is less than about 15×10 −7 /K.

5. The glass-ceramic of claim 1 , wherein the glass-ceramic exhibits an integrated visible transmission (Tl) between about 0.3% to about 6% wherein said integrated visible transmission (Tl) is measured using an illuminant D65, 2° observer test on 4 mm thick glass-ceramic.

6. The glass-ceramic of claim 1 , wherein the glass-ceramic exhibits an optical transmission, measured at about 625 nm, higher than about 3.5%, and wherein said optical transmission is measured using an illuminant D65, 2° observer test on 4 mm thick glass-ceramic.

7. The glass-ceramic of claim 1 , wherein the glass-ceramic exhibits an optical transmission, measured at about 950 nm, between about 35-75%, wherein said optical transmission is measured using an illuminant D65, 2° observer test on 4 mm thick glass-ceramic.

8. The glass-ceramic of claim 1 , wherein the glass-ceramic exhibits an infra-red optical transmission, measured at about 1600 nm, of greater than 45%, wherein said optical transmission is measured using an illuminant D65, 2° observer test on 4 mm thick glass-ceramic.

9. The glass-ceramic of claim 1 , wherein the glass-ceramic is substantially free of As 2 O 3 and Sb 2 O 3 .

10. The glass-ceramic of claim 7 , further comprising (in weight %): 0-2.5% ZrO 2 , and 1.5-4% TiO 2 .

11. The glass-ceramic of claim 9 , further comprising (in weight %): 0-3% MgO, 0-3% ZnO, 0-5% BaO, 0-2% CaO, 0-1.5% K 2 O, 0-1.5% Na 2 O.

12. The glass-ceramic of claim 11 , wherein a combined amount of CaO, K 2 O, and Na 2 O is less than about 1.5%.

13. The glass-ceramic of claim 9 , further comprising (in weight %): 0-0.6% SnO 2 .

14. A glass-ceramic of the lithium aluminosilicate type comprising a solid solution of β-spodumene as the predominant crystalline phase and exhibiting, for a thickness of 4 mm:
a light transmittance of from 0.3 to 6%;
an optical transmittance for a wavelength of 625 nm of greater than 2.0%;
an optical transmittance for a wavelength of 950 nm of from 35 to 75%;
an optical transmittance for a wavelength of 1600 nm of at least 45%; and
L*, a*, b* colorimetric coordinates in diffuse reflection for an illuminant D65 and a reference observer at 2° such that 15.0≦L*≦40.0, −3.0≦a*≦4.0 and −10.0≦b*≦4.0,
said glass-ceramic further comprising (in weight %):
SnO 2 0.1-0.6%;
V 2 O 5 0.05-0.20%;
Cr 2 O 3 0.015-0.30%;
Fe 2 O 3 0.15-0.30%; and
As 2 O 3 +Sb 2 O 3 <0.1%.

15. A glass-ceramic cooktop comprising the glass-ceramic according to claim 1 .

16. A glass-ceramic cooktop comprising the glass-ceramic according to claim 14 .

Assignees

• Eurokera

Inventors

• Comte Marie Jacqueline Monique
• Jousseaume Cécile
• Lehuede Philippe
• Plevacova Kamila

Classifications

• F24C15/10

  Tops, e.g. hot plates; Rings (cover lids or splash guards F24C15/12; spillage trays or grooves F24C15/14) · CPC title

• C03C10/0027 Primary

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

• C03C4/02

  for coloured glass · CPC title

• C03C3/085

  containing an oxide of a divalent metal · CPC title

• C03B32/02 Primary

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