US4074992A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sodium ion-exchange on surface of beta-spodumene
Assignee: Corning Glass Works
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Filing: 1968-12-18
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Granted: 1978-02-21
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Expires: 1988-12-18
Abstract
Abstract This invention relates to the strengthening of glass-ceramic articles wherein the crystal content thereof comprises the predominant portion and containing beta-spodumene solid solution as the principal crystal phase. The strengthening is effected by means of an ion exchange process taking place within the crystals in a surface layer of the article such that sodium ions from an external source are exchanged for lithium ions in the crystal phase thereby causing compressive stresses to be set up in the surface layer.
Inventors
- 👤 Raymond O. Voss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:53
CPC Classifications
C; C03; C03C; C03C21/00; C03C21/001; C03C21/002; C03C10/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
139 words
A method for making a unitary glass-ceramic article of high strength wherein the crystal content thereof constitutes at least 50% by weight of the article with a surface compressive stress layer and an interior portion which comprises contacting a glass-ceramic article consisting essentially of Li 2 O, Al 2 O 3 , and SiO 2 , wherein the crystal phase therein consists essentially of beta-spodumene solid solution, at a temperature above 200° C. with a source of exchangeable sodium ions for a period of time sufficient to replace at least part of the lithium ions of said beta-spodumene solid solution in a surface layer of the article with a corresponding amount of sodium ions, said replacement not changing the essential crystal structure of the beta-spodumene solid solution crystals but thereby effecting a compressively stressed surface layer on the article.
Claim 2
Independent Claim
139 words
A method for making a unitary glass-ceramic article of high strength wherein the crystal content thereof constitutes at least 50% by weight of the article with a surface compressive stress layer and an interior portion which comprises contacting a glass-ceramic article consisting essentially of Li 2 O, Al 2 O 3 , and SiO 2 , wherein the crystal phase therein consists essentially of beta-spodumene solid solution, at a temperature above 200° C. with a source of exchangeable sodium ions for a period of time sufficient to replace at least part of the lithium ions of said beta-spodumene solid solution in a surface layer of the article with a corresponding amount of sodium ions, said replacement not changing the essential crystal structure of the beta-spodumene solid solution crystals but thereby effecting a compressively stressed surface layer on the article.
Claim 3
Dependent Claim
19 words
A method according to claim 1 wherein TiO 2 is present in the glass-ceramic article as a nucleating agent.
Claim 4
Dependent Claim
25 words
A method according to claim 1, wherein said article is contacted with a source of exchangeable sodium ions at a temperature between about 200°-600° C.
Claim 5
Dependent Claim
109 words
A unitary glass-ceramic article of high strength wherein the crystal content thereof constitutes at least 50% by weight of the article with a surface compressive stress layer and an interior portion consisting essentially of Li 2 O, Al 2 O 3 , and SiO 2 , wherein the crystals of said interior portion consist essentially of beta-spodumene solid solution and the crystals of said surface compressive stress layer consist essentially of beta-spodumene solid solution, the crystal structure of said latter crystals being essentially unchanged but in at least a portion of which the proportion of lithium ions is less with a corresponding increase in an amount of sodium ions.
Claim 6
Dependent Claim
109 words
A unitary glass-ceramic article of high strength wherein the crystal content thereof constitutes at least 50% by weight of the article with a surface compressive stress layer and an interior portion consisting essentially of Li 2 O, Al 2 O 3 , and SiO 2 , wherein the crystals of said interior portion consist essentially of beta-spodumene solid solution and the crystals of said surface compressive stress layer consist essentially of beta-spodumene solid solution, the crystal structure of said latter crystals being essentially unchanged but in at least a portion of which the proportion of lithium ions is less with a corresponding increase in an amount of sodium ions.
Claim 7
Dependent Claim
16 words
A glass-ceramic article according to claim 4 wherein TiO 2 is present as a nucleating agent.
References Cited (Backward Citations)
US3157522A
Cited
US3647489A
Cited
US3428513A
Cited
FR1439341A
Cited
GB1105434A
Cited
US3218220A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-20 | 1981-08-22 | 1982-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-20 | 1985-08-22 | 1986-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-20 | 1989-08-22 | 1990-02-21 | $7700.00 | Window Closed / Lapsed |