Prestress by use of a gradient material

Patent metadata

Field	Value
Publication number	US-11780765-B2
Application number	US-202117316150-A
Country	US
Kind code	B2
Filing date	May 10, 2021
Priority date	May 8, 2020
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

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.

First claim

What is claimed is:

1. 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 CTE K calculated according to the following formula (14) in a range of 3.0 to 7.0 ppm/K and the surface glass has a CTE O calculated according to formula (14) which in comparison to the CTE K 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 E pot is a depth of potential well.

2. The glass article according to claim 1 , wherein the core glass is characterized by the following constituent phases of the core glass:

Constituent phase
Min. (% by mol)
Max. (% by mol)

reedmergnerite
12
75

potassium reedmergnerite
0
25

albite
0.5
45

cordierite
0
5

anorthite
0
20

diboron trioxide
0
15

silicon dioxide
10
55;

and wherein the surface glass is characterized by the following constituent phases of the surface glass:

Constituent phase
Min. (% by mol)
Max. (% by mol)

reedmergnerite
2.5
55

potassium reedmergnerite
0
35

albite
1
65

cordierite
0

Assignees

• Schott Ag

Inventors

• Eichholz Rainer Erwin
• Ollig Markus
• Riecke Arne
• Fotheringham Ulrich

Classifications

• C03C3/111 Primary

  containing nitrogen · CPC title

• C03C3/064 Primary

  containing boron · CPC title

• C03C3/089

  containing boron · CPC title

• C03C2201/32

  containing aluminium (C03C2201/36 takes precedence) · CPC title

• C03C2201/58

  containing metals in non-oxide form, e.g. CdSe · CPC title