US4126477A
Expired / Lapsed
US
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Beta-spodumene glass-ceramics exhibiting excellent dimensional stability
Assignee: Corning Glass Works
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Filing: 1977-05-06
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Granted: 1978-11-21
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Expires: 1997-05-06
Abstract
Abstract This invention is directed to the production of glass-ceramic articles having compositions within the Li 2 O-Al 2 O 3 -SiO 2 field nucleated with a combination of TiO 2 + ZrO 2 wherein beta-spodumene solid solution constitutes the primary crystal phase. Mullite and/or corundum along with ZrTiO 4 solid solution and, occasionally, ZrO 2 solid solution are present as secondary crystal phases. Because of their low coefficients of thermal expansion and exceptional long time dimensional stability at temperatures up to 1000° C., the compositions can be useful in applications where extreme changes in temperature are experienced; for example, the construction of honeycomb structures used in regenerative heat exhchangers for turbine engines.
Inventors
- 👤 Richard F. Reade
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:02
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0018; C03C10/0027
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
223 words
A method for making an opaque a glass-ceramic article demonstrating an average coefficient of thermal expansion (0°-1000° C.) less than about 20 × 10 -7 /° C. and a change in length of less than about 750 PPM after an exposure of 1000 hours to temperatures up to 950° C. consisting essentially of fine-grained crystals of beta-spodumene solid solution, mullite and/or corundum, ZrTiO 4 solid solution, and, occasionally, ZrO 2 solid solution uniformly dispersed within a glassy matrix, said crystals constituting at least 75% by volume of the article which consists of the steps: a. melting a batch for a glass consisting essentially, in weight percent on the oxide basis, of 3.7-7.5% Li 2 O, 18.5-33% Al 2 O 3 , 55-75% SiO 2 , and 3.4-5.0% Ro 2 , wherein RO 2 consists of 1.5-2.5% TiO 2 and 1-2.7% ZrO 2 in a molar ratio TiO 2 :ZrO 2 between about 3:1-1:1; b. simultaneously cooling the melt to at least within the transformation range and shaping a glass article of a desired configuration therefrom; c. heating said glass article to a temperature between about 1150°-1350° C. to cause the crystallization in situ of fine-grained crystals of beta-spodumene solid solution, mullite and/or corundum, ZrTiO 4 solid solution, and, occasionally, ZrO 2 solid solution; and then d. cooling the crystallized article to room temperature.
Claim 2
Independent Claim
223 words
A method for making an opaque a glass-ceramic article demonstrating an average coefficient of thermal expansion (0°-1000° C.) less than about 20 × 10 -7 /° C. and a change in length of less than about 750 PPM after an exposure of 1000 hours to temperatures up to 950° C. consisting essentially of fine-grained crystals of beta-spodumene solid solution, mullite and/or corundum, ZrTiO 4 solid solution, and, occasionally, ZrO 2 solid solution uniformly dispersed within a glassy matrix, said crystals constituting at least 75% by volume of the article which consists of the steps: a. melting a batch for a glass consisting essentially, in weight percent on the oxide basis, of 3.7-7.5% Li 2 O, 18.5-33% Al 2 O 3 , 55-75% SiO 2 , and 3.4-5.0% Ro 2 , wherein RO 2 consists of 1.5-2.5% TiO 2 and 1-2.7% ZrO 2 in a molar ratio TiO 2 :ZrO 2 between about 3:1-1:1; b. simultaneously cooling the melt to at least within the transformation range and shaping a glass article of a desired configuration therefrom; c. heating said glass article to a temperature between about 1150°-1350° C. to cause the crystallization in situ of fine-grained crystals of beta-spodumene solid solution, mullite and/or corundum, ZrTiO 4 solid solution, and, occasionally, ZrO 2 solid solution; and then d. cooling the crystallized article to room temperature.
Claim 3
Dependent Claim
29 words
A method according to claim 1 wherein said glass article is heated to a temperature between about 750°-950° C. to cause nucleation prior to heating to about 1150°-1350° C.
Claim 4
Dependent Claim
43 words
A method according to claim 1 wherein said glass also contains up to 1.5% MgO and has a molar ratio Li 2 O:MgO of at least 2:1 and a molar ratio Al 2 O 3 :(Li 2 O + MgO) between about 1.2-1.5.
Claim 5
Dependent Claim
13 words
An opaque glass-ceramic article made in accordance with the method of claim 1.
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) | 1981-11-20 | 1982-05-22 | 1982-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-20 | 1986-05-22 | 1986-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-20 | 1990-05-22 | 1990-11-21 | $7700.00 | Window Closed / Lapsed |