Thermally stable, chemically resistant glass composition

• US 5,506,180 A
• Filed: 08/04/1994
• Issued: 04/09/1996
• Est. Priority Date: 06/25/1992
• Status: Expired due to Term

• Current Assignee: Saint-Gobain Vitrage International
• Original Assignee: Saint-Gobain Vitrage International
• Inventors: Ponthieu, Christine
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Sample, David
• Application Number:
  US08/285,775
• Time in Patent Office: 614 Days
• Field of Search: 501/66, 501/70, 501/72
• US Class Current: 501/66
• CPC Class Codes: C03C 3/091 containing aluminium

Abstract

The present invention relates to a thermally stable, chemically resistant glass composition incorporating the following constituents within the ranges given hereinafter as cationic percentages:

______________________________________                                    

SiO₂ 46 to 56% Al₂ O₃ 12 to 17% B₂ O₃ 10 to 23% CaO 9 to 15% MgO 0.5 to 4% SrO 2 to 7% BaO 0 to 4% Na₂ O + K₂ O ≦0.5% TiO₂ 0 to 3% ______________________________________

The glass composition can be used for producing containers, fire-proof glazings or substrates for the electronics industry.

Claims

1. A thermally stable, chemically resistant glass substrate consisting essentially of in ranges given herein after as cationic percentages:

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 46 to 56% Al.sub.2 O.sub.3 12 to 17% B.sub.2 O.sub.3 10 to 23% CaO 9 to 15% MgO 0.5 to 4% SrO 2 to 7% BaO 0 to 4% Na.sub.2 O + K.sub.2 O ≦

0.5% TiO.sub.2 0 to 3% ______________________________________

and having a viscosity curve such that the difference between the temperatures corresponding to viscosities of log η

=4.5 and log η

=2.5 is <

330°

C.;

an expansion coefficient ≦

50×

10^-7 /°

C.;

a temperature corresponding to log η

=3.5>

the liquidus temperature; and

a temperature corresponding to log η

=4≦

1140°

C.; and

wherein said glass substrate is ZnO free.

2. The glass substrate according to claim 1, wherein the combined amount of SiO₂ and Al₂ O₃ remains equal to or below 65%.

3. The glass substrate according to claim 1, wherein the CaO content is between 10 and 14%.

4. The glass substrate according to claim 1, wherein the combined amount of SrO and BaO is equal to or below 4%.

5. The glass substrate according to claim 1, wherein the Na₂ O content is below 0.2%.

6. The thermally stable, chemically resistant glass substrate of claim 1, wherein the difference between the temperatures corresponding to viscosities of log η

=4.5 and log η

=2.5 is <

300°

C.