US4403017A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low thermal expansion modified cordierites
Assignee: Applied Biosystems Inc
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Filing: 1981-11-30
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Granted: 1983-09-06
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Expires: 2001-11-30
Abstract
Abstract A modified cordierite (2MgO.2Al 2 O 3 .5SiO 2 ) composition in which at least a portion of the silicon dioxide is replaced with germanium oxide. These compositions have low thermal expansion, excellent formability and thermal shock resistance making them especially suitable for the manufacture of mirror substrates to be used at elevated temperatures. By selecting the proportion of germanium oxide according to the intended operating temperature, substantially zero thermal expansion can be achieved between room temperature and the selected operating temperature. Methods of manufacturing the material and of selecting the thermal expansion characteristics are also disclosed.
Inventors
- 👤 Jean-Marie Bind
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:39
CPC Classifications
G; G02; G02B; G02B1/00; G02B1/02; C; C04; C04B; C04B35/00; C04B35/01; C04B35/16; C04B35/18; C04B35/195; G02B5/00; G02B5/08
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
47 words
A polycrystalline sintered ceramic single phase structure having improved thermal expansion and sintering characteristics, having the cordierite structure and the composition, on a molecular basis of: about 2 moles magnesium oxide, about 2 moles aluminum oxide, and about 5 moles divided between silicon dioxide and germanium oxide.
Claim 2
Dependent Claim
47 words
A polycrystalline sintered ceramic single phase structure having improved thermal expansion and sintering characteristics, having the cordierite structure and the composition, on a molecular basis of: about 2 moles magnesium oxide, about 2 moles aluminum oxide, and about 5 moles divided between silicon dioxide and germanium oxide.
Claim 3
Dependent Claim
34 words
The ceramic structure according to claim 1 wherein said composition contains about 5-x moles silicon dioxide and about x moles germanium oxide, and "x" is a positive number from about 0.1 to about 2.
Claim 4
Independent Claim
88 words
The method of manufacturing ceramic single phase structures having improved thermal expansion and sintering characteristics which comprises the steps of: providing, on a molecular basis, a mixture of about 2 moles magnesium oxide, about 2 moles aluminum oxide, and about 5 moles divided between silicon dioxide and germanium oxide; milling said mixture until finely divided and thoroughly mixed; forming said mixture into a desired shape; gradually heating said shape to a temperature at which sintering occurs and a cordierite type structure is formed; and gradually cooling said structure.
Claim 5
Independent Claim
88 words
The method of manufacturing ceramic single phase structures having improved thermal expansion and sintering characteristics which comprises the steps of: providing, on a molecular basis, a mixture of about 2 moles magnesium oxide, about 2 moles aluminum oxide, and about 5 moles divided between silicon dioxide and germanium oxide; milling said mixture until finely divided and thoroughly mixed; forming said mixture into a desired shape; gradually heating said shape to a temperature at which sintering occurs and a cordierite type structure is formed; and gradually cooling said structure.
Claim 6
Dependent Claim
33 words
The method according to claim 3 wherein said mixture contains about 5-x moles silicon dioxide and about x moles germanium oxide, and "x" is a positive number from about 0.1 to about 2.
Claim 7
Dependent Claim
41 words
The method according to claim 3 wherein said shape is sintered by gradually heating said shape to about 1000°-1100° C. over about 10 to 30 hours, then heating the shape to the sintering temperature over an additional 2 to 6 hours.
Claim 8
Dependent Claim
48 words
The method according to claim 3 wherein said shape is sintered by gradually heating said shape to about 1100° C. over about 20 hours, then heating said shape to final sintering temperature of from about 1250° C. to 1400° C. over an additional about 2 to 6 hours.
Claim 9
Dependent Claim
34 words
The method according to claim 3 wherein said milling is accomplished by ball milling said mixture for at least about 12 hours and an anti-coagulation agent is added to the mixture prior to milling.
Claim 10
Dependent Claim
25 words
The method according to claim 3 wherein said shape is formed by pressing said mixture at a pressure of from about 10,000 to 50,000 psi.
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) | 1986-09-05 | 1987-03-07 | 1987-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-05 | 1991-03-07 | 1991-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-05 | 1995-03-07 | 1995-09-06 | $7700.00 | Window Closed / Lapsed |