Patent US3854919A successfully refreshed from Google Patents.
US3854919A
Expired / Lapsed
US
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Method of forming transparent glass ceramic with compression layer
Assignee: OI Glass Inc
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Filing: 1973-03-01
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Granted: 1974-12-17
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Expires: 1993-03-01
Abstract
Abstract High-strength glass-ceramics and a method of producing glassceramics having high strengths and good thermal shock resistance wherein a thermally crystallizable glass containing a nucleating agent capable of changing valency and which is more effective in the changed valency state is thermally in situ crystallized in a reducing atmosphere to form an at least partially crystalline glass-ceramic having a coefficient of thermal expansion which is considerably lower than that of the parent glass and having a high compressive stress layer on its surface.
Inventors
- 👤 P Pirooz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:34
CPC Classifications
B; B32; B32B; B32B17/00; B32B17/06; C; C03; C03B; C03B27/00; C03B27/012; C03B32/00; C03B32/02; C03C; C03C10/00; C03C10/0018; C03C10/0027
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
70 words
A METHOD OF FORMING A TRANSPARENT GLASS CERAMIC BODY HVING A COMPRESSIVE STRESS LAYER ON THE SURFACE TTHEREOF AND WHEREBY THERE IS IMPARTED TO SAID BODY A HIGH MECHANICAL STRENGTH OF AT LEAST 20,000 PSI AND WHEREBY SAID BODY WHEN BROKEN WILL SHATTER INTO VERY SMALL PARTICLES INSTEAD OF LARGE, JAGGED PIECES, SAID METHOD CONSISTING ESSENTIALLY OF A. SUBJECTING A THERRMALLY CRYSTALLIZABLE GLASS BODY CONSISTING ESSENTIALLY OF THE FOLLOWING COMPOSITION
Claim 2
Independent Claim
70 words
A METHOD OF FORMING A TRANSPARENT GLASS CERAMIC BODY HVING A COMPRESSIVE STRESS LAYER ON THE SURFACE TTHEREOF AND WHEREBY THERE IS IMPARTED TO SAID BODY A HIGH MECHANICAL STRENGTH OF AT LEAST 20,000 PSI AND WHEREBY SAID BODY WHEN BROKEN WILL SHATTER INTO VERY SMALL PARTICLES INSTEAD OF LARGE, JAGGED PIECES, SAID METHOD CONSISTING ESSENTIALLY OF A. SUBJECTING A THERRMALLY CRYSTALLIZABLE GLASS BODY CONSISTING ESSENTIALLY OF THE FOLLOWING COMPOSITION
Claim 3
Dependent Claim
48 words
The method as defined in claim 1 wherein at least 95 percent by weight of said body consists of said SiO2, Al2O3, Li2O, CuO and nucleating agent and the remainder of the composition consists of compatible metal oxides which will not adversely affect the properties of the glass-ceramic.
Claim 4
Dependent Claim
30 words
The method as defined in claim 1 wherein said compressive stress layer is formed to a depth of from about 100 to 500 microns on the surface of said body.
Claim 5
Dependent Claim
21 words
The method as defined in claim 1 wherein the compressive stress in said surface layer is about 30,000 to 80,000 psi.
Claim 6
Dependent Claim
31 words
The method as defined in claim 1 wherein said reducing atmosphere is selected from the group consisting of mixtures of nitrogen and hydrogen, carbon monoxide, steam, natural gas and mixtures thereof.
Claim 7
Dependent Claim
19 words
A method as defined in claim 1 wherein the thermally crystallizable glass body consists essentially of the following composition
Claim 8
Dependent Claim
18 words
The method as defined in claim 1 wherein said nucleating temperature is from about 750* to about 875*C.
Claim 9
Dependent Claim
24 words
The method as defined in claim 1 wherein said nucleating temperature and the temperature at which said crystallization occurs is substantially the same temperature.
Claim 10
Dependent Claim
18 words
The method as defined in claim 1 wherein said reducing atmosphere is a mixture of nitrogen and hydrogen.
Claim 11
Dependent Claim
13 words
The method as defined in claim 1 wherein said reducing atmosphere is steam.
Claim 12
Dependent Claim
25 words
The method as defined in claim 1 wherein said CuO is present in an amount of from about 1 to about 3.5 percent by weight.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |