US4280845A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cordierite ceramic
Assignee: NGK Insulators Ltd
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Filing: 1979-12-27
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Granted: 1981-07-28
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Expires: 1999-12-27
Abstract
Abstract Cordierite ceramic consisting mainly of cordierite in crystal phase after fired and having a mean pore size of 2-50 microns and a thermal expansion coefficient of not more than 16×10 -7 (1/° C.) over the range of 25-1000° C. and being produced by starting from a batch including a magnesia raw material with an average particle size of 5-150 microns.
Inventors
- 👤 Tadaaki Matsuhisa
- 👤 Shigeo Soejima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:36
CPC Classifications
B; B01; B01J; B01J21/00; B01J21/14; C; C04; C04B; C04B35/00; C04B35/01; C04B35/16; C04B35/18; C04B35/195; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24149
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
129 words
A process for the preparation of cordierite ceramic consisting mainly of cordierite in crystal phase after fired, and having a mean pore size of 2-50 microns and a thermal expansion coefficient of not more than 16×10 -7 (1/°C.) in the range of 25°-1000° C., characterized in that a starting material having a chemical composition consisting of 42-52% by weight of silica, 34-48% by weight of alumina and 10-18% by weight of magnesia, in which an average particle size of magnesia starting material is 5-150 microns, is fired by raising temperature at a rate of 30°-300° C./hr in the temperatures above 1100° to control formation of a liquid phase appearing during firing and then keeping a peak temperature for sufficient time to attain crystallization of cordierite from the liquid phase.
Claim 2
Dependent Claim
129 words
A process for the preparation of cordierite ceramic consisting mainly of cordierite in crystal phase after fired, and having a mean pore size of 2-50 microns and a thermal expansion coefficient of not more than 16×10 -7 (1/°C.) in the range of 25°-1000° C., characterized in that a starting material having a chemical composition consisting of 42-52% by weight of silica, 34-48% by weight of alumina and 10-18% by weight of magnesia, in which an average particle size of magnesia starting material is 5-150 microns, is fired by raising temperature at a rate of 30°-300° C./hr in the temperatures above 1100° to control formation of a liquid phase appearing during firing and then keeping a peak temperature for sufficient time to attain crystallization of cordierite from the liquid phase.
Claim 3
Dependent Claim
31 words
A process as claimed in claim 1, wherein said magnesia starting material is at least one of talc, calcined talc, magnesite, calcined magnesite, brucite, magnesium carbonate, magnesium hydroxide and magnesium oxide.
Claim 4
Dependent Claim
24 words
A process as claimed in claim 1, wherein said average particle size of the magnesia starting material is within a range of 21-50 microns.
Claim 5
Dependent Claim
24 words
A process as claimed in claim 2, wherein said average particle size of the magnesia starting material is within a range of 26-50 microns.
Claim 6
Dependent Claim
29 words
A process as claimed in claim 1, wherein said chemical composition consists of 44-51% by weight of silica, 34-45% by weight of alumina and 11-15% by weight of magnesia.
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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) | 1984-07-27 | 1985-01-26 | 1985-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-27 | 1989-01-26 | 1989-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-27 | 1993-01-26 | 1993-07-28 | $7700.00 | Window Closed / Lapsed |