US4467039A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Potassium fluorrichterite glass ceramics and method
Assignee: Corning Glass Works
•
Filing: 1983-05-09
•
Granted: 1984-08-21
•
Expires: 2003-05-09
Abstract
Abstract There is disclosed a highly crystalline glass-ceramic article exhibiting superior toughness against fracture propagation, a modulus of rupture in excess of 20,000 psi, a predominant crystal phase of potassium fluorrichterite, and having an overall composition consisting essentially of SiO 2 : 50-70 CaO: 4-15 MgO: 8-25 F: 3-8 Na 2 O: 2-9 K 2 O: 2-12 Li 2 O: 0-3 Al 2 O 3 : 0-7 Canasite may be a secondary phase, but a crystal phase composed essentially of potassium fluorrichterite is preferred for dinnerware.
Inventors
- 👤 George H. Beall
- 👤 John E. Megles, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:11
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/16
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
73 words
A highly crystalline glass-ceramic article exhibiting high toughness and a modulus of rupture in excess of 20,000 psi, wherein the predominant crystal phase is potassium fluorrichterite and having an overall composition consisting essentially, expressed in terms of weight percent on the oxide basis, of about SiO 2 : 50-70 CaO: 4-15 MgO: 8-25 F: 3-8 Na 2 O: 2-9 K 2 O: 2-12 Li 2 O: 0-3 Al 2 O 3 : 0-7.
Claim 2
Dependent Claim
73 words
A highly crystalline glass-ceramic article exhibiting high toughness and a modulus of rupture in excess of 20,000 psi, wherein the predominant crystal phase is potassium fluorrichterite and having an overall composition consisting essentially, expressed in terms of weight percent on the oxide basis, of about SiO 2 : 50-70 CaO: 4-15 MgO: 8-25 F: 3-8 Na 2 O: 2-9 K 2 O: 2-12 Li 2 O: 0-3 Al 2 O 3 : 0-7.
Claim 3
Dependent Claim
15 words
A glass-ceramic article in accordance with claim 1 wherein canasite is a secondary crystal phase.
Claim 4
Dependent Claim
21 words
A glass-ceramic article in accordance with claim 2 wherein the ratio of potassium fluorrichterite crystals to canasite crystals is about 7:3.
Claim 5
Dependent Claim
58 words
A glass-ceramic article in accordance with claim 1 wherein potassium fluorrichterite essentially constitutes the crystal phase and the calculated composition, expressed in terms of percent by weight on the oxide basis, is SiO 2 : 57-68 Al 2 O 3 : 0-4 CaO: 0-3 CaF 2 : 7-12. Na 2 O: 2.5-5 K 2 O: 3-7 MgO: 14-18
Claim 6
Dependent Claim
17 words
A glass-ceramic article in accordance with claim 4 wherein the SiO 2 content is at least 62%.
Claim 7
Dependent Claim
25 words
A glass-ceramic article in accordance with claim 4 wherein the composition further includes up to about one percent each of BaO and Li 2 O.
Claim 8
Dependent Claim
42 words
A glass-ceramic article in accordance with claim 4 wherein the calculated composition is essentially SiO2, 65%; Al 2 O 3 , 2%; MgO, 141/2%; CaF 2 , 9%; Na 2 O, 4%; K 2 O, 31/2%, Li 2 O, 1%; BaO, 1%.
References Cited (Backward Citations)
US2948629A
Cited
US3201266A
Cited
US3384508A
Cited
US3720526A
Cited
US3516810A
Cited
US3839056A
Cited
US3905824A
Cited
US4341872A
Cited
US4386162A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-08-21 | 1988-02-20 | 1988-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-21 | 1992-02-20 | 1992-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-21 | 1996-02-20 | 1996-08-21 | $7700.00 | Window Closed / Lapsed |