US4263381A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sintering of beta-type alumina bodies using alpha-alumina encapsulation
Assignee: United States Department of Energy
•
Filing: 1978-10-27
•
Granted: 1981-04-21
•
Expires: 1998-10-27
Abstract
Abstract A method of sintering a shaped green, beta-type alumina body comprising: (A) inserting said body into an open chamber prepared by exposing the interior surface of a container consisting essentially of at least about 50 weight percent of alpha-alumina and a remainder of other refractory material to a sodium oxide or sodium oxide producing environment; (B) sealing the chamber; and heating the chamber with the shaped body encapsulated therein to a temperature and for a time necessary to sinter said body to the desired density. The encapsulation chamber prepared as described above is also claimed.
Inventors
- 👤 Bryan J. McEntire
- 👤 Anil V. Virkar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:26
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/113
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
39 words
An article of manufacture comprising a tubular capsule consisting essentially of alpha aluminum having a deposit of sodium oxide on its interior surfaces and having encapsulated therein a shaped green beta-type alumina bisque of compacted powder ready for sintering.
Claim 2
Dependent Claim
39 words
An article of manufacture comprising a tubular capsule consisting essentially of alpha aluminum having a deposit of sodium oxide on its interior surfaces and having encapsulated therein a shaped green beta-type alumina bisque of compacted powder ready for sintering.
Claim 3
Dependent Claim
40 words
An article in accordance with claim 1 wherein said sodium oxide deposit on said interior surface was deposited thereon by exposure to a sodium environment at a temperature of at least about 1400° C. for at least about 8 hours.
Claim 4
Dependent Claim
26 words
An article in accordance with claim 1 wherein the cross-section of said capsule has a "V" configuration at its base and is curved on the top.
Claim 5
Dependent Claim
41 words
An article in accordance with claim 1 wherein said capsule includes a noble metal reaction barrier adapted to support the shaped body to be sintered such that said barrier separates said body from direct contact the interior surface of said chamber.
Claim 6
Independent Claim
116 words
A method of preparing a sintered beta-type alumina body comprising: providing a tubular capsule consisting essentially of alpha alumina; encapsulating a sodium oxide bearing compound capable of releasing sodium oxide vapor at temperatures above 1250° C. within said capsule; heating said capsule to a temperature in excess of 1250° C. for more than 1 hour to deposit sodium oxide onto the interior surface of said capsule; cooling said capsule and removing the remaining sodium oxide bearing compound therefrom; encapsulating a shaped green bisque of compacted beta type alumina powder into said capsule; and heating said capsule to a sintering temperature in excess of 1500° C. for a sufficient time to provide the sintered beta-type alumina body.
Claim 7
Independent Claim
116 words
A method of preparing a sintered beta-type alumina body comprising: providing a tubular capsule consisting essentially of alpha alumina; encapsulating a sodium oxide bearing compound capable of releasing sodium oxide vapor at temperatures above 1250° C. within said capsule; heating said capsule to a temperature in excess of 1250° C. for more than 1 hour to deposit sodium oxide onto the interior surface of said capsule; cooling said capsule and removing the remaining sodium oxide bearing compound therefrom; encapsulating a shaped green bisque of compacted beta type alumina powder into said capsule; and heating said capsule to a sintering temperature in excess of 1500° C. for a sufficient time to provide the sintered beta-type alumina body.
Claim 8
Dependent Claim
44 words
A method in accordance with claim 5 wherein said sodium oxide bearing compound is selected from the group consisting of sodium aluminate, sodium acetate, sodium carbonate and Na 2 O. X Al 2 O 3 wherein X is less than or equal to 11.
Claim 9
Dependent Claim
32 words
A method in accordance with claim 6 wherein said step of encapsulating a sodium oxide bearing compound comprises coating the interior surface of said capsule with an aqueous solution of sodium carbonate.
Claim 10
Dependent Claim
33 words
A method in accordance with claim 5 wherein said capsule with encapsulated sodium oxide bearing compound is heated to a temperature of at least about 1400° C. for at least about 8 hours.
References Cited (Backward Citations)
US3468719A
Cited
US3495630A
Cited
US3655845A
Cited
US3950463A
Cited
US3607435A
Cited
US3903225A
Cited
US3707589A
Cited
US3819785A
Cited
US3896019A
Cited
NL7602945A
Cited
US4056589A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-04-20 | 1984-10-20 | 1985-04-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-20 | 1988-10-20 | 1989-04-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-20 | 1992-10-20 | 1993-04-21 | $7700.00 | Window Closed / Lapsed |