US3997352A
Expired / Lapsed
US
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Mica-spodumene glass-ceramic articles
Assignee: Corning Glass Works
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Filing: 1975-09-29
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Granted: 1976-12-14
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Expires: 1995-09-29
Abstract
Abstract This invention is concerned with the production of glass-ceramic articles wherein phlogopite mica solid solution and beta-spodumene solid solution comprise the primary crystal phases. Such articles demonstrate good machineability characteristics along with low coefficients of thermal expansion, excellent thermal shock resistance, and relatively high refractoriness.
Inventors
- 👤 George H. Beall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:57
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0036; C03C10/0045
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
181 words
A glass-ceramic article exhibiting good machineability and a coefficient of thermal expansion (25°-500° C.) less than about 50 × 10 - 7 /° C. consisting essentially of interlocking plates of fluormica crystals and very fine-grained beta-spodumene solid solution crystals dispersed within a glassy matrix, said fluormica crystals comprising at least 50% of the total crystallization and having a grain size of at least 3 microns with a crystalline aspect ratio of at least 4:1, and said beta-spodumene solid solution crystals comprising at least 25% of the total crystallization and having a grain size less than about one micron, the sum of said crystals constituting at least 70% by volume of the article and being formed through the crystallization in situ of a glass body consisting essentially, by weight on the oxide basis, of about 3-30% R 2 O + RO, wherein R 2 O consists of 0-10% K 2 O and/or Na 2 O, and RO consists of 0-25% SrO and/or BaO, 1-5% Li 2 O, 8-25% MgO, 10-25% Al 2 O 3 , 35-65% SiO 2 , and 3-12% F.
Claim 2
Dependent Claim
181 words
A glass-ceramic article exhibiting good machineability and a coefficient of thermal expansion (25°-500° C.) less than about 50 × 10 - 7 /° C. consisting essentially of interlocking plates of fluormica crystals and very fine-grained beta-spodumene solid solution crystals dispersed within a glassy matrix, said fluormica crystals comprising at least 50% of the total crystallization and having a grain size of at least 3 microns with a crystalline aspect ratio of at least 4:1, and said beta-spodumene solid solution crystals comprising at least 25% of the total crystallization and having a grain size less than about one micron, the sum of said crystals constituting at least 70% by volume of the article and being formed through the crystallization in situ of a glass body consisting essentially, by weight on the oxide basis, of about 3-30% R 2 O + RO, wherein R 2 O consists of 0-10% K 2 O and/or Na 2 O, and RO consists of 0-25% SrO and/or BaO, 1-5% Li 2 O, 8-25% MgO, 10-25% Al 2 O 3 , 35-65% SiO 2 , and 3-12% F.
Claim 3
Dependent Claim
42 words
A glass-ceramic article according to claim 1 exhibiting excellent electrical properties wherein said glass body contains less than 6% K 2 O, less than 3% Li 2 O, and is essentially free from Na 2 O and B 2 O 3 .
Claim 4
Dependent Claim
33 words
A glass-ceramic article according to claim 1 wherein said K 2 O and/or Na 2 O is wholly or partly replaced on a molar basis with Rb 2 O and/or Cs 2 O.
Claim 5
Dependent Claim
23 words
A glass-ceramic article according to claim 1 wherein said SrO and/or BaO is wholly or partly replaced on a molar basis with PbO.
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) | 1979-12-14 | 1980-06-14 | 1980-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-12-14 | 1984-06-14 | 1984-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-12-14 | 1988-06-14 | 1988-12-14 | $7700.00 | Window Closed / Lapsed |