US4568650A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oxidation of reduced ceramic products
Assignee: United States Department of the Navy
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Filing: 1984-01-17
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Granted: 1986-02-04
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Expires: 2004-01-17
Abstract
Abstract A method of reoxidizing a partially-reduced ceramic. The partially reduced ceramic is heated in a chamber having a non-oxidizing atmosphere. An oxidizing gas is then introduced into the chamber at a rate which is sufficiently slow that cracking will not occur.
Inventors
- 👤 William S. Coblenz
- 👤 Roy W. Rice
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 11:31
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/01; C04B35/48; C04B35/486; C04B35/50; C30; C30B; C30B29/00; C30B29/10; C30B29/16; C30B29/22; C30B33/00
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
72 words
A method of reoxidizing a partially reduced-ceramic, comprising the steps of: heating ceramic, which has been partially reduced throughout substantially all of its bulk, in a non-oxidizing atmosphere to a temperature at which said partially-reduced ceramic obtains a desired degree of stress relief capability; thereafter, exposing said partially-reduced ceramic to an oxidizing atmosphere until said partially reduced ceramic has been oxidized to the desired degree, before cooling removes the stress relief capability.
Claim 2
Independent Claim
72 words
A method of reoxidizing a partially reduced-ceramic, comprising the steps of: heating ceramic, which has been partially reduced throughout substantially all of its bulk, in a non-oxidizing atmosphere to a temperature at which said partially-reduced ceramic obtains a desired degree of stress relief capability; thereafter, exposing said partially-reduced ceramic to an oxidizing atmosphere until said partially reduced ceramic has been oxidized to the desired degree, before cooling removes the stress relief capability.
Claim 3
Dependent Claim
32 words
The method of claim 1 wherein said heating step comprises the step of heating said partially-reduced ceramic until said partially-reduced ceramic achieves a temperature which is about 50-80% of its melting temperature.
Claim 4
Dependent Claim
13 words
The method of claim 2 wherein said ceramic is a partially-reduced metal oxide.
Claim 5
Dependent Claim
13 words
The method of claim 3 wherein said oxidizing atmosphere consists essentially of oxygen.
Claim 6
Dependent Claim
19 words
The method of claim 3 wherein the ceramic is ZrO 2 , CeO 2 , or a mixture thereof.
Claim 7
Dependent Claim
13 words
The method of claim 5 wherein the said ceramic is ZrO 2 .
Claim 8
Dependent Claim
18 words
The method of claim 5 wherein said ceramic contains Ce and Zr atoms in the ratio of 4:1.
Claim 9
Dependent Claim
31 words
The process of claim 7 in which heating is conducted in a chamber and further comprising the step of choosing and maintaining a total pressure within said chamber of 1 atmosphere.
Claim 10
Independent Claim
100 words
A method of oxidizing a ceramic, comprising the steps of: placing a ceramic, which has been partially reduced throughout its bulk, into a chamber having a non-oxidizing atmosphere; thereafter, heating the said ceramic to a temperature at which stress relief takes place; before cooling removes the stress relief capability, exposing said partially-reduced ceramic to an oxidizing atmosphere until said partially reduced ceramic has been oxidized to the desired degree to form a reoxidized ceramic; controlling the rate at which said partially reduced ceramic is exposed to said oxidizing atmosphere so that said ceramic remains in a stress-balanced state during oxidation.
Claim 11
Independent Claim
100 words
A method of oxidizing a ceramic, comprising the steps of: placing a ceramic, which has been partially reduced throughout its bulk, into a chamber having a non-oxidizing atmosphere; thereafter, heating the said ceramic to a temperature at which stress relief takes place; before cooling removes the stress relief capability, exposing said partially-reduced ceramic to an oxidizing atmosphere until said partially reduced ceramic has been oxidized to the desired degree to form a reoxidized ceramic; controlling the rate at which said partially reduced ceramic is exposed to said oxidizing atmosphere so that said ceramic remains in a stress-balanced state during oxidation.
Claim 12
Dependent Claim
19 words
The method of claim 9 wherein the fully oxidized form of the ceramic is a partially reduced metal oxide.
Claim 13
Dependent Claim
11 words
The method of claim 10 wherein said oxidizing atmosphere is oxygen.
Claim 14
Dependent Claim
17 words
The method of claim 11 wherein the fully-oxidized form of said partially-reduced ceramic comprises ZrO 2 .
Claim 15
Dependent Claim
13 words
The method of claim 12 wherein said fully-oxidized ceramic is ZrO 2 .
Claim 16
Dependent Claim
13 words
The method of claim 10 wherein said fully-oxidized ceramic is CeO 2 .
Claim 17
Dependent Claim
22 words
The method of claim 10 wherein said fully-oxidized ceramic comprises 80 mole percent CeO 2 and 20 mole percent ZrO 2 .
Claim 18
Independent Claim
119 words
A method of reoxidizing a partially-reduced ceramic, comprising the steps of: heating a ceramic body, which has been partially-reduced in a major portion of its bulky, in a non-oxidizing atmosphere to a temperature at which said partially-reduced ceramic obtains a desired degree of stress relief capability; before cooling removes stress relief capability exposing said partially-reduced ceramic to an oxidizing atmosphere until said partially reduced ceramic is oxidized throughout substantially all of its bulk to the desired degree to form a reoxidized ceramic; controlling the rate at which said partially reduced ceramic is exposed to said oxidizing atmosphere so that said ceramic remains in a stress-balanced during oxidation and said reoxidized ceramic does not contain a significant amount of stress.
Claim 19
Independent Claim
119 words
A method of reoxidizing a partially-reduced ceramic, comprising the steps of: heating a ceramic body, which has been partially-reduced in a major portion of its bulky, in a non-oxidizing atmosphere to a temperature at which said partially-reduced ceramic obtains a desired degree of stress relief capability; before cooling removes stress relief capability exposing said partially-reduced ceramic to an oxidizing atmosphere until said partially reduced ceramic is oxidized throughout substantially all of its bulk to the desired degree to form a reoxidized ceramic; controlling the rate at which said partially reduced ceramic is exposed to said oxidizing atmosphere so that said ceramic remains in a stress-balanced during oxidation and said reoxidized ceramic does not contain a significant amount of stress.
Claim 20
Dependent Claim
14 words
The method of claim 16 wherein the ceramic is a partially reduced metal oxide.
Claim 21
Dependent Claim
11 words
The method of claim 17 wherein said oxidizing atmosphere is oxygen.
Claim 22
Dependent Claim
23 words
The method of claim 18 wherein the fully-oxidized form of said partially-reduced ceramic is ZrO 2 , CeO 2 or a mixture thereof.
Claim 23
Dependent Claim
13 words
The method of claim 19 wherein said fully-oxidized ceramic is ZrO 2 .
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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) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |