US3751238A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of chemically strengthening a silicate article containing soda
Assignee: Corning Glass Works
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Filing: 1970-02-25
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Granted: 1973-08-07
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Expires: 1990-02-25
Abstract
Abstract This invention relates to the treatment of a silicate glass article to develop strengthening compressive stresses within a surface layer on the article by introducing potassium ions into the glass surface layer in exchange for sodium ions. It is more particularly concerned with an improved method of treatment to increase the depth of ion exchange within the glass surface within a given time while maintaining the central tension in the article at a relatively low level.
Inventors
- 👤 P Grego
- 👤 R Howell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:33
CPC Classifications
C; C03; C03C; C03C21/00; C03C21/001; C03C21/002
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
70 words
A method according to claim 1 wherein the first contact of the surface of said article with a source of potassium ions is carried out at a temperature above the strain point but below the deformation point of the glass for at least five minutes to thereby cause the exchange of potassium ions for sodium ions and the glass rearrangement and stress release by molecular flow to take place concurrently.
Claim 2
Dependent Claim
41 words
A method according to claim 2 wherein the first contact of the surface of said article with a source of potassium ions is carried out at a temperature between about 600*-800*C. for a time between about 5 minutes to 2 hours.
Claim 3
Dependent Claim
89 words
A method according to claim 1 wherein the first contact of the surface of said article with a source of potassium ions is carried out at a temperature below the strain point of the glass but above about 200*C. to cause the exchange of potassium ions for sodium ions and thereafter said article is heated to a temperature above the strain point but below the deformation point of the glass for at least five minutes to cause the glass rearrangement and stress release by molecular flow to take place.
Claim 4
Dependent Claim
26 words
A method according to claim 1 wherein the sodium silicate glass consists essentially, by weight, of 5-25% Na2O, 5-25% Al2O3 and/or ZrO2, and the balance SiO2.
Claim 5
Dependent Claim
51 words
A method according to claim 1 wherein, after the first contact of the surface of said article with a source of potassium ions, said article is heated in a gaseous atmosphere at a temperature above the annealing point but below the deformation point of the glass for at least 5 minutes.
Claim 6
Dependent Claim
27 words
A method according to claim 6 wherein said article is heated at a temperature between about 600*-800*C. for a time between about 5 minutes to 1 hour.
Claim 7
Dependent Claim
36 words
A method according to claim 6 wherein said gaseous atmosphere contains an effective amount of an acidic gas to react with alkali metal oxides which form on the surface of said article during the heating thereof.
Claim 8
Dependent Claim
16 words
A method according to claim 8 wherein said acidic gas consists of an oxide of sulfur.
Claim 9
Dependent Claim
30 words
A method according to claim 1 wherein the source of potassium ions for each contact with the surface of said article consists of a bath of a molten potassium salt.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |