US3647489A
Expired / Lapsed
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Glass ceramics
Assignee: English Electric Co Ltd
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Filing: 1969-08-13
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Granted: 1972-03-07
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Expires: 1989-08-13
Abstract
Abstract A high-alumina glass-ceramic product with a substantial proportion microcrystalline is formed from a glass by thermal treatment, the main crystal phase being beta-spodumene or betaeucryptite, and the product having a thermal coefficient of expansion of less than 40 X 10 7/*C. At least 90 percent of the composition comprises major constituents and nucleating agents as follows, in percentages by weight: Major constituents: SiO2 55-75Al2O3 15-30 Li2O 2-15MgO 0-20 Nucleating agents: P2O5, 0.5-6.0 percent, together with one of the following metallic oxides: A. MoO3 0.5-4.0 b. WO3 0.5-4.0 c.V2O5 0.52.0 d. TiO2 0.2-less than 2. The thermal coefficient of expansion is less than 40 X 10 7. An alternative nucleating agent is cadmium sulpho-selenide.
Inventors
- 👤 Peter William Mcmillan
- 👤 Graham Partridge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:41
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0018; C03C10/0027
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
47 words
A glass-ceramic product as claimed in claim 1 containing as optional minor constituents, up to a total of not more than 10 percent by weight, any of the following, in percentages by weight: I. Na2O and K2O together 0-5 ii. ZnO 0-8.9 iii. CaO 0-5.0 iv. B2O30-7.6.
Claim 2
Dependent Claim
81 words
A glass-ceramic material formed by devitrification of a glass consisting of major constituents which, together with a nucleating agent, make up at least 90 percent by weight of the total composition and lie in the glass system consisting essentially of: SiO245-88% Al2O3 0-36% Li2O 0-27% MgO 0-32% optional minor constituents consisting essentially of alkali metal oxides 0-5 percent; zinc oxide 0-8.9 percent; calcium oxide 0-5 percent; and boric oxide 0-10 percent; and a nucleating agent being cadmium-sulpho-selenide 0.5-2.0 percent by weight.
Claim 3
Dependent Claim
120 words
A hard, dense, mechanically strong, high-alumina glass-ceramic product of which at least a substantial proportion is microcrystalline, consisting essentially of a composition having major constituents and a nucleating agent which together form at least 90 percent of the composition, said major constituents consisting of SiO2, Al2O3, Li2O and optionally of MgO within the following ranges in percentages by weight: SiO255-75 Al2O315-30 Li2O 2-15 MgO 0-20 and said composition containing as nucleating agent the combination of P2O5 and TiO2 within the following ranges in percentages by weight: P2O50.5-6.0 TiO20.2-less than 2 said product having its main crystal phase selected from the group consisting of beta-spodumene and beta-eucryptite, and having a coefficient of thermal expansion of less than 25 X 10 7.
Claim 4
Dependent Claim
62 words
A glass-ceramic product as claimed in claim 4 containing as optional minor constituents, up to a total of not more than 10 percent, any of the following in the stated percentages by weight: i. Na2O and K2O 0 - 5, but not exceeding 5 percent in combined total, ii. ZnO 0 - 8.9 iii. CaO - 5.0 iv. B2O3 - - 7.6.
Claim 5
Dependent Claim
117 words
A hard, dense, mechanically strong, high-alumina glass-ceramic product of which at least a substantial proportion is microcrystalline, consisting essentially of a composition having major constituents and a nucleating agent which together form at least 90 percent of the composition, said major constituents consisting of SiO2, Al2O3, Li2O and optionally MgO within the following ranges in percentages by weight: SiO255-75 Al2O315-30 Li2O 2-15 MgO 0-20 and said composition containing as nucleating agent the combination of P2O5 and V2O5 within the following ranges in percentages by weight: P2O50.5-6.0 V2O50.5-2.0 said product having its main crystal phase selected from the group consisting of beta-spodumene and beta-eucryptite, and having a coefficient of thermal expansion of less than 25 X 10 7.
Claim 6
Dependent Claim
20 words
A glass-ceramic product as claimed in claim 1 wherein said TiO2 is present in the range 0.2 - 1.5 percent.
Claim 7
Dependent Claim
21 words
A glass-ceramic product as claimed in claim 4 wherein said TiO2 is present in the range 0 .2 - 1.5 percent.
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) | 1975-03-07 | 1975-09-06 | 1976-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-07 | 1979-09-06 | 1980-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-07 | 1983-09-06 | 1984-03-07 | $7700.00 | Window Closed / Lapsed |