Glass ceramics having low rhodium levels

Patent metadata

Field	Value
Publication number	US-9868663-B2
Application number	US-201615200571-A
Country	US
Kind code	B2
Filing date	Jul 1, 2016
Priority date	May 30, 2013
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A glass ceramic precursor glass and a glass ceramic having low levels of rhodium and a method of controlling the amount of rhodium in such glasses and glass ceramics. The precursor glass and glass ceramic contain from about 1 ppm to about 10 ppm and, in certain embodiments, from about 1 ppm to about 6 ppm rhodium. The method of controlling of reducing rhodium dissolution from a rhodium-containing material such as, for example, an alloy into a glass melt comprises controlling and/or lowering the partial pressure of oxygen at the rhodium-containing vessel/glass interface by imposing a high humidity condition around the external (non-glass-contact) surface of the rhodium-containing material. The lower concentration of rhodium minimizes its coloring effect on the white color of the glass ceramic.

First claim

The invention claimed is:

1. A method, comprising:
a. providing a melt of a precursor glass, wherein the melt is in contact with a rhodium-containing material;
b. exposing an external surface that is not in contact with the melt of the rhodium-containing material to an atmosphere containing water vapor, wherein the water vapor suppresses dissolution of rhodium in the melt, and
c. forming a lithia-alumina-silica glass ceramic from the melt, the glass ceramic having an opacity of at least 85% over a wavelength range of 400 to 700 nm and having CIELAB color space coordinates L*, a*, and b*, wherein L* is at least 92, b* is at least −0.3, and wherein the glass ceramic comprises from 1 ppm to about 10 ppm rhodium.

2. The method of claim 1 , wherein the atmosphere has a dew point in a range from about −40° C. to about 90° C.

3. The method of claim 2 , wherein the dew point is about 90° C.

4. The method of claim 1 , wherein the melt is at a temperature in a range from about 1600° C. to about 1700° C.

5. The method of claim 1 , where the melt comprises from 1 ppm to about 6 ppm rhodium.

6. The method of claim 1 , further comprising ion exchanging the lithia-alumina-silica glass ceramic.

7. The method of claim 6 , wherein the ion exchanged lithia-alumina-silica glass ceramic has a layer extending from a surface of the lithia-alumina-silica glass ceramic to a depth of layer, wherein the layer has a compressive stress of at least 300 MPa, and wherein the depth of layer is at least about 30 microns.

8. The method of claim 1 , wherein the lithia-alumina-silica glass ceramic comprises from 1 ppm to about 6 ppm rhodium.

9. The method of claim 1 , wherein the atmosphere comprises water vapor, oxygen, and nitrogen.

10. The method of claim 1 , wherein the rhodium-containing material is a platinum-rhodium alloy.

11. The method of claim 10 , wherein the platinum-rhodium alloy comprises about 80% platinum and about 20% rhodium.

12. The method of claim 1 wherein the rhodium-containing material is in the form of a vessel containing the melt.

13. The method of claim 1 , wherein the melt is at a temperature in a range from about 1600° C. to about 1650° C.

14. The method of claim 1 , wherein the glass ceramic comprises: from about 62 to about 75 mol % SiO 2 ; from about 10.5 to about 17 mol % Al 2 O 3 ; from about 5 to about 13 mol % Li 2 O; from 0 to about 4 mol % ZnO; from about 0 to about 8 mol % MgO; from about 2 to about 5 mol % TiO 2 ; from 0 to about 4 mol % B 2 O 3 ; from 0 to about 5 mol % Na 2 O; from 0 to about 4 mol % K 2 O; from 0 to about 2 mol % ZrO 2 ; from 0 to about 7 mol % P 2 O 5 ; from 0 to about 0.3 mol % Fe 2 O 3 ; from 0 to about 2 mol % MnOx, and from about 0.05 to about 0.2 mol % SnO 2 , at least one β-spodumene solid solution comprising at least about 70 wt % of the crystalline phases of the glass-ceramic, at least one titanium-containing crystalline phase having an acicular morphology and a rutile phase.

15. The method of claim 1 , wherein L* is in a range from about 92.3 to about 94, and a* is in a range from about −0.10 to about −0.50.

16. The method of claim 1 , wherein the glass ceramic is transparent to radio waves ranging in frequency from about 3 kHz to about 300 GHz.

17. The method of claim 1 , wherein the glass ceramic is ion exchangeable.

Assignees

• Corning Inc

Inventors

• Biswas Samir
• Fu Qiang
• Lineman David Myron
• Stewart Ronald Leroy

Classifications

• C03C2204/04

  Opaque glass, glaze or enamel · CPC title

• C03C3/093

  containing zinc or zirconium · CPC title

• C03C21/002

  to perform ion-exchange between alkali ions (C03C21/005 takes precedence) · CPC title

• Y10T428/315

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

• C03C1/02 Primary

  Pretreated ingredients · CPC title