Refractory object, glass overflow forming block, and process for glass object manufacture

Patent metadata

Field	Value
Publication number	US-9714185-B2
Application number	US-201514738217-A
Country	US
Kind code	B2
Filing date	Jun 12, 2015
Priority date	Mar 11, 2011
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

A refractory object can include at least 10 wt % Al 2 O 3 . In an embodiment, the refractory object can further include a dopant including an oxide of a rare earth element, Ta, Nb, Hf, or any combination thereof. In another embodiment, the refractory object may have a property such that the averaged grain size does not increase more than 500% during sintering, an aspect ratio less than approximately 4.0, a creep rate less than approximately 1.0×10 −5 μm/(μm×hr), or any combination thereof. In a particular embodiment, the refractory object can be in the form of a refractory block or a glass overflow forming block. The glass overflow forming block can be useful in forming an Al—Si—Mg glass sheet. In a particular embodiment, a layer including Mg—Al oxide can initially form along exposed surfaces of the glass overflow forming block when forming the Al—Si—Mg glass sheet.

First claim

What is claimed is:

1. A refractory object used in forming a glass object, wherein the refractory object comprises:
at least 95 wt % Al 2 O 3 ;
at least 1.1 wt % and not greater than 5 wt % of a dopant including Ta 2 O 5 , HfO 2 , Pr 2 O 3 , Gd 2 O 3 , CeO 2 , Dy 2 O 3 or any combination thereof; and
substantially no Ti, Ca, Si, Fe, Na, or any combination thereof
wherein the refractory object has a creep rate of no greater than approximately 5.0×10 −6 μm/(μm×hr) as measured at a temperature of 1275° C.

2. The refractory object according to claim 1 , wherein the refractory object has an amount of the first dopant sufficient to keep an averaged grain size from increasing more than 300% during a sintering operation.

3. The refractory object according to claim 1 , wherein the refractory object has grains with an averaged aspect ratio of no greater than approximately 4.0.

4. The refractory object according to claim 1 , wherein the glass object is in a form of a glass sheet.

5. The refractory object according to claim 4 , wherein the glass sheet has a thickness of at least approximately 20 μm.

6. The refractory object according to claim 4 , wherein the glass object includes an alkali glass.

7. The refractory object according to claim 1 , further comprising a second dopant that includes a sintering agent.

8. The refractory object of claim 7 , wherein the second dopant is distinct from the first dopant and wherein the second dopant includes Zr, Hf, Mg, Y, Sc, Yb, Pr, Sm, Gd, La, Ce, Dy, or any combination thereof.

9. A refractory object used in forming a glass object, wherein the refractory object comprises:
at least 95 wt % Al 2 O 3 ;
at least 1.1 wt % and not greater than 5 wt % of a dopant including Ta 2 O 5 , HfO 2 , Pr 2 O 3 , Gd 2 O 3 , CeO 2 , Dy 2 O 3 or any combination thereof; and
a concentration of not greater than 0.05 wt. % SiO 2 , TiO 2 , Fe 2 O 3 , Na 2 O, CaO or any combination thereof
wherein the refractory object has a creep rate of no greater than approximately 5.0×10 −6 μm/(μm×hr) as measured at a temperature of 1275° C.

10. The refractory object of claim 9 , wherein the refractory object has a porosity of at least approximately 0.1%.

11. The refractory object of claim 10 , wherein the refractory object has a porosity no greater than approximately 9.0 vol %.

12. The refractory object of claim 9 , wherein the refractory object has no outer layer.

13. The refractory object of claim 9 , wherein the refractory object has a length of at least approximately 0.5 m.

Assignees

• Saint-Gobain Ceram & Plastics Inc

Inventors

• Citti Olivier
• Kazmierczak Andrea L

Classifications

• C04B2235/788

  Aspect ratio of the grains · CPC title

• C04B2235/3206

  Magnesium oxides or oxide-forming salts thereof · CPC title

• C04B35/62665

  Flame, plasma or melting treatment · CPC title

• C04B2235/77

  Density · CPC title

• C04B2235/3463

  Alumino-silicates other than clay, e.g. mullite · CPC title