US3801295A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mica glass-ceramics
Assignee: Corning Glass Works
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Filing: 1972-08-01
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Granted: 1974-04-02
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Expires: 1992-08-01
Abstract
Abstract This invention relates to the production of glass-ceramic articles wherein the predominant crystal phase is a synthetic fluormica. The articles have compositions with the K2O-MgO-Al2O3B2O3-SiO2-F field with microstructures consisting of very large (>150 microns), essentially two-dimensional crystals of high aspect ratio uniformly distributed throughout the articles. This feature of easily cleavable flakes dispersed in a brittle matrix imparts excellent machineability, high fracture energy, and superior thermal shock damage resistance.
Inventors
- 👤 G Beall
- 👤 C Chyung
- 👤 H Watkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:18
CPC Classifications
C; C03; C03B; C03B32/00; C03B32/02; C03C; C03C10/00; C03C10/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
36 words
A method according to claim 1 wherein the glass article is held between the annealing point and the temperature at which the melt exhibits a viscosity of about 1,000 poises for about 5 to 30 minutes.
Claim 2
Dependent Claim
22 words
A method according to claim 1 wherein said time to cause the article to crystallize in situ ranges between about 1/2-24 hours.
Claim 3
Dependent Claim
44 words
A method according to claim 1 wherein said glass article is first exposed to a temperature between about 600*-900*C. for about 1-6 hours and thereafter exposed to a temperature between about 1,000*-1,150*C. for about 1-8 hours to cause the article to crystallize in situ.
Claim 4
Independent Claim
167 words
A method for producing a glass-ceramic article demonstrating a modulus of rupture of about 2,000-5,000 psi, a fracture energy value of about 2-5 X 104 ergs/cm2, and exceptional resistance to thermal shock consisting essentially of fluorophlogopite solid solution crystals having a diameter of at least 150 microns and an aspect ratio of at least 20 dispersed in a glassy matrix, said crystals constituting between about 50-75 percent by volume of the article, which comprises: a. melting a batch for a glass consisting essentially, by weight on the oxide basis, of about 4-6 percent K2O, 16-19.5 percent MgO, 14-19 percent Al2O3, 6-14 percent B2O3, 35-45 percent SiO2, and 6-10 percent F; b. cooling the melt to a glass article at least below the transformation range thereof; and c. exposing said glass article to a temperature between about 1, 000*-1,150*C. for a sufficient length of time to cause said article to crystallize in situ to a glass-ceramic article consisting essentially of fluorophlogopite solid solution dispersed in a glassy matrix.
Claim 5
Dependent Claim
22 words
A method according to claim 5 wherein said time to cause the article to crystallize in situ ranges between about 1/2-24 hours.
Claim 6
Dependent Claim
44 words
A method according to claim 5 wherein said glass article is first exposed to a temperature between about 600*-900*C. for about 1-6 hours and thereafter exposed to a temperature between about 1,000*-1,150*C. for about 1-8 hours to cause the article to crystallize in situ.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |