Prestress by use of a gradient material
AssigneeSchott AG
InventorsRainer Erwin Eichholz, Markus Ollig, Arne Riecke, Ulrich Fotheringham
Life of this patent
Estimating the term…
Abstract
The invention relates to glass articles, such as for example glass tubes or flat glasses, where the material at the surface by a targeted process control has gradient material properties which in turn result in a compressive prestress of the surface. The invention also relates to a method for the production of the glass articles as well as their use.
Claims20
A glass article, comprising a core glass and a surface glass, wherein the surface glass is present down to a depth of <20 nm and the core glass is present at least in a depth of 500 nm, wherein the core glass is characterized by the following constituent phases of the core glass:
- Constituent phase
- Min. (% by mol)
- Max. (% by mol)
- reedmergnerite
- 10
- 80
- potassium reedmergnerite
- 0
- 30
- albite
- 0
- 50
- cordierite
- 0
- 10
- anorthite
- 0
- 25
- diboron trioxide
- 0
- 20
- silicon dioxide
- 5
- 60;
- wherein the surface glass is characterized by the following constituent phases of the surface glass:
- Constituent phase
- Min. (% by mol)
- Max. (% by mol)
- reedmergnerite
- 2
- 60
- potassium reedmergnerite
- 0
- 40
- albite
- 0
- 70
- cordierite
- 0
- 10
- anorthite
- 0
- 20
- diboron trioxide
- 0
- 15
- silicon dioxide
- 6
- 80;
- wherein the core glass has a CTEK calculated according to the following formula (14) in a range of 3.0 to 7.0 ppm/K and the surface glass has a CTEO calculated according to formula (14) which in comparison to the CTEK of the core glass calculated according to formula (14) is lower by at least 0.6 ppm/K:
- CTE
- glass
- =
- (
- 50116.33042
- (
- kJ
- mol
- )
- E
- pot
- _
- -
- 26.1724514
- )
-
- ppm
- /
- K
- ;
- (
- 35
- )
- wherein Epot is a depth of potential well.
Dependencies are inferred from the claim text.