US3856497A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making crystallized glass
Assignee: PPG Industries Inc
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Filing: 1973-03-22
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Granted: 1974-12-24
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Expires: 1993-03-22
Abstract
Abstract Crystallized glass has hitherto been made by the use of the mineral petalite as the source of lithium values. Petalite is in short supply, and when attempts are made to use lithium carbonate or a similar lithium salt in place of petalite in the glass batch, unwanted microcracking develops during a subsequent crystallizing heat treatment with certain glass compositions. Such microcracking can be avoided by using a purposefully small addition to the petalite-free batch of an alkali metal salt, wherein the alkali metal is selected from the class consisting of potassium, rubidium and cesium.
Inventors
- 👤 M Hummel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:33
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0036; C03B; C03B32/00; C03B32/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
218 words
A METHOD OF MAKING A CRYSTALLIZED GLASS ARTICLE SUBSTANTIALY FREE OF MICROCRACKING, COMPRISING: A. PREPARING A GLASS BATCH CONSISTING ESSENTIALLY OF (1) A SILICA, 82) AN ALUMINA, (3) LITHIUM FAMILY GLASS BATCH INGREDIENT CONSISTING OF A LITHIUM SALT, AND (4) A ZINC SALT IN AN AMOUNT SUFFICIENT TO PROVIDE A CRYSTALLIZED GLASS ARTICLES FROM SAID GLASS BATCH HAVING A ZNO CONTENT, PERCENT BY WEIGHT ON AN OXIDE WEIGHT BASIS OF 1 TO 3.8, WHICH CRYSTALLIZED GLASS ARTICLE OBTAINED UPON COOLING A MELT OF SAID GLASS BATCH, FORMING AND HEAT TREATING SAID ARTICLE IS CHARACTERIZED BY THE PRESENCE OF MICROCRACKS IN THE SURFACE THEREOF; B. ADDING TO SAID GLASS BATCH AN ALKALI METAL SALT WHEREIN THE ALKALI METAL IS A MEMBER OF THE GROUP CONSISTING OF POTASSIUM, RUBIDIUM AND CESIUM, SAID ALKALI METAL SALT BEING PRESENT IN AN AMOUNT SUFFICIENT TO PROVIDE A GLAS ARTICLE UPON COOLING A MELT OF SAID GLASS BATCH HAVING A CONTENT OF AN OXIDE OF THE ALKALI METAL OF SAID SALT, PERCENT BY WEIGHT ON AN OXIDE WEIGHT BASIS, OF 0.15 TO 2.50; C. MELTING THE GLASS BATCH CONTAINING THE INGREDIENTS SET FORTH IN (A) AND (B) TO FORM A GLASS MELT; D. COOLING SAID GLASS MELT AND SUBSEQUENTLY THEREWITH; E. FORMING A GLASS ARTICLE HAVING THE FOLLOWING COMPOSITION ON AN OXIDE WEIGHT BASIS:
Claim 2
Independent Claim
218 words
A METHOD OF MAKING A CRYSTALLIZED GLASS ARTICLE SUBSTANTIALY FREE OF MICROCRACKING, COMPRISING: A. PREPARING A GLASS BATCH CONSISTING ESSENTIALLY OF (1) A SILICA, 82) AN ALUMINA, (3) LITHIUM FAMILY GLASS BATCH INGREDIENT CONSISTING OF A LITHIUM SALT, AND (4) A ZINC SALT IN AN AMOUNT SUFFICIENT TO PROVIDE A CRYSTALLIZED GLASS ARTICLES FROM SAID GLASS BATCH HAVING A ZNO CONTENT, PERCENT BY WEIGHT ON AN OXIDE WEIGHT BASIS OF 1 TO 3.8, WHICH CRYSTALLIZED GLASS ARTICLE OBTAINED UPON COOLING A MELT OF SAID GLASS BATCH, FORMING AND HEAT TREATING SAID ARTICLE IS CHARACTERIZED BY THE PRESENCE OF MICROCRACKS IN THE SURFACE THEREOF; B. ADDING TO SAID GLASS BATCH AN ALKALI METAL SALT WHEREIN THE ALKALI METAL IS A MEMBER OF THE GROUP CONSISTING OF POTASSIUM, RUBIDIUM AND CESIUM, SAID ALKALI METAL SALT BEING PRESENT IN AN AMOUNT SUFFICIENT TO PROVIDE A GLAS ARTICLE UPON COOLING A MELT OF SAID GLASS BATCH HAVING A CONTENT OF AN OXIDE OF THE ALKALI METAL OF SAID SALT, PERCENT BY WEIGHT ON AN OXIDE WEIGHT BASIS, OF 0.15 TO 2.50; C. MELTING THE GLASS BATCH CONTAINING THE INGREDIENTS SET FORTH IN (A) AND (B) TO FORM A GLASS MELT; D. COOLING SAID GLASS MELT AND SUBSEQUENTLY THEREWITH; E. FORMING A GLASS ARTICLE HAVING THE FOLLOWING COMPOSITION ON AN OXIDE WEIGHT BASIS:
Claim 3
Dependent Claim
13 words
The method of claim 1, in which the lithium salt is lithium carbonate.
Claim 4
Dependent Claim
22 words
The method of claim 2, in which the alkali metal salt is selected from the class consisting of carbonates, fluorides and sulfates.
Claim 5
Dependent Claim
49 words
The method of claim 1, in which the content of the alkali metal selected from the group consisting of potassium, rubidium and cesium of the glass measured as the oxide is within the range of 0.17 to 0.60 percent by weight based on total weight of the glass composition.
Claim 6
Dependent Claim
18 words
The method of claim 1, in which the crystalline phase is a solid solution of beta-spodumene and silica.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |