Patent US3337243A successfully refreshed from Google Patents.
US4074993A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Potassium ion-exchange on surface of beta-spodumene
Assignee: Corning Glass Works
•
Filing: 1968-03-18
•
Granted: 1978-02-21
•
Expires: 1988-03-18
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 effect is accomplished through an ion exchange process taking place within a surface layer of the article such that potassium 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
- 👤 Roger G. Ackerman
- 👤 Bruce R. Karstetter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:54
CPC Classifications
C; C03; C03C; C03C21/00; C03C21/001; C03C21/002; C03C10/00; C03C3/00; C03C3/04; C03C3/076; C03C3/083; C03C3/085
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
133 words
A method for producing 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 at a temperature between about 550°-800° C. with a source of potassium ions for a period of time sufficient to replace at least part of the lithium ions of said beta-spodumene in a surface layer of the article with a corresponding amount of potassium ions, said replacement not changing the essential crystal structure of the beta-spodumene crystals to thereby effect a compressively stressed surface layer on the article.
Claim 2
Independent Claim
133 words
A method for producing 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 at a temperature between about 550°-800° C. with a source of potassium ions for a period of time sufficient to replace at least part of the lithium ions of said beta-spodumene in a surface layer of the article with a corresponding amount of potassium ions, said replacement not changing the essential crystal structure of the beta-spodumene crystals to thereby effect a compressively stressed surface layer on the article.
Claim 3
Dependent Claim
28 words
A method according to claim 1 wherein said time sufficient to replace at least part of the lithium ions of said beta-spodumene does not exceed about 16 hours.
Claim 4
Dependent Claim
25 words
A method according to claim 1 wherein said glass-ceramic article is contacted with said source of potassium ions at a temperature between about 700°-800° C.
Claim 5
Dependent Claim
105 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 and the crystals of said surface compressive stress layer consist essentially of beta-spodumene, 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 potassium ions.
Claim 6
Dependent Claim
105 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 and the crystals of said surface compressive stress layer consist essentially of beta-spodumene, 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 potassium ions.
References Cited (Backward Citations)
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 |