Patent US4151235A successfully refreshed from Google Patents.
US4151235A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of beta-alumina
Assignee: Chloride Silent Power Ltd
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Filing: 1977-08-04
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Granted: 1979-04-24
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Expires: 1997-08-04
Abstract
Abstract A method of producing a beta-alumina ceramic article containing a doping addition of magnesium oxide or of magnesium oxide and lithium oxide, comprising the steps of wet-milling a precursor material or emulsification of an already powdered precursor material to form an aqueous slurry, spray-drying the slurry to produce a powder, forming the powder into a green shape and sintering the shape, wherein the precursor material contains at least some of the magnesium oxide in the form of magnesium aluminate.
Inventors
- 👤 Geoffrey J. May
- 👤 Stephen R. Tan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:42
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/113
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
72 words
A method of producing a beta-alumina ceramic article from a precursor material containing a doping addition of magnesium oxide or of magnesium oxide and lithium oxide, comprising the steps of spray-drying an aqueous slurry of the precursor material to produce a powder, forming the powder into a green shape and sintering the shape, and wherein the precursor material contains at least some of the magnesium oxide in the form of magnesium aluminate.
Claim 2
Independent Claim
72 words
A method of producing a beta-alumina ceramic article from a precursor material containing a doping addition of magnesium oxide or of magnesium oxide and lithium oxide, comprising the steps of spray-drying an aqueous slurry of the precursor material to produce a powder, forming the powder into a green shape and sintering the shape, and wherein the precursor material contains at least some of the magnesium oxide in the form of magnesium aluminate.
Claim 3
Independent Claim
79 words
A method of producing a beta-alumina ceramic article containing a doping addition of magnesium oxide, or magnesium oxide and lithium oxide, comprises the steps of wet-milling a precursor material or emulsification of an already powdered precursor material to form an aqueous slurry, spray-drying the slurry to produce a powder, forming the powder into a green shape and sintering the shape, and wherein the precursor material contains at least some of the magnesium oxide in the form of magnesium aluminate.
Claim 4
Independent Claim
79 words
A method of producing a beta-alumina ceramic article containing a doping addition of magnesium oxide, or magnesium oxide and lithium oxide, comprises the steps of wet-milling a precursor material or emulsification of an already powdered precursor material to form an aqueous slurry, spray-drying the slurry to produce a powder, forming the powder into a green shape and sintering the shape, and wherein the precursor material contains at least some of the magnesium oxide in the form of magnesium aluminate.
Claim 5
Dependent Claim
19 words
A method as claimed in claim 1 wherein all the magnesium oxide is in the form of magnesium aluminate.
Claim 6
Dependent Claim
29 words
A method as claimed in claim 3 wherein the precursor material comprises a mixture of magnesium aluminate together with alpha-alumina and sodium oxide or sodium aluminate or sodium hydroxide.
Claim 7
Dependent Claim
31 words
A method as claimed in claim 1 wherein lithium is included in the precursor material in the form of lithium oxide or lithium carbonate or lithium hydroxide or as lithium aluminate.
Claim 8
Dependent Claim
29 words
A method as claimed in claim 1 wherein the precursor material comprises sodium oxide or sodium hydroxide or sodium aluminate and a mixed magnesium lithium aluminate together with alpha-alumina.
Claim 9
Dependent Claim
38 words
A method as claimed in claim 1 wherein the spray-drying is effected using a stream of hot gas into which the slurry or the emulsion is fed and wherein the required powders are separated from the gas stream.
Claim 10
Dependent Claim
20 words
A method as claimed in claim 1 wherein the green shape is produced from the powdered material by isostatic pressing.
Claim 11
Dependent Claim
29 words
A method as claimed in claim 1 wherein the green shape is sintered by a rapid-sintering technique in which the green shape is moved continuously through a sintering furnace.
Claim 12
Dependent Claim
32 words
A method as claimed in claim 9 wherein the green shape is pre-fired at a temperature between 500° and 1000° C. for a period between 10 minutes and 10 hours before sintering.
Claim 13
Dependent Claim
27 words
A method as claimed in claim 9 wherein the prefiring is carried out between 850° and 950° C. for a period of between 4 and 6 hours.
Claim 14
Dependent Claim
36 words
A method as claimed in claim 9 wherein the sintering is effected in a pass-through furnace at temperatures between 1550° and 1800° C. at a speed between 10 mm per minute and 100 mm per minute.
Claim 15
Dependent Claim
21 words
A method as claimed in claim 1 wherein the article is annealed after sintering at a temperature below the sintering temperature.
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) | 1982-04-23 | 1982-10-23 | 1983-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-23 | 1986-10-23 | 1987-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-23 | 1990-10-23 | 1991-04-24 | $7700.00 | Window Closed / Lapsed |