Patent US4495116A successfully refreshed from Google Patents.
US4495116A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polycrystalline translucent alumina sintered body, a method for producing the same and a high pressure vapor discharge lamp obtained by using said sintered body
Assignee: NGK Insulators Ltd
•
Filing: 1982-10-19
•
Granted: 1985-01-22
•
Expires: 2002-10-19
Abstract
Abstract A polycrystalline translucent alumina sintered body having high in-line transmission, which is suitable for an envelope for a high pressure vapor discharge lamp, is produced by adding to alumina powder having a purity of more than 99.8% MgO or a compound forming MgO in an amount of 0.01-0.1% by weight calculated as MgO, La 2 O 3 or a compound forming La 2 O 3 in an amount of 0.001-0.05% by weight calculated as La 2 O 3 , and Y 2 O 3 or a compound forming Y 2 O 3 in an amount of 0.001-0.05% by weight calculated as Y 2 O 3 , thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under vacuum or either atmosphere of hydrogen gas or dissociated ammonia gas under oxygen concentration of 10 -15 -10 -25 atm.
Inventors
- 👤 Masayuki Kaneno
- 👤 Takehiro Kajihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:56
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/30; H01J61/302; C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/115; Y; Y10; Y10S; Y10S264/00; Y10S264/91
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
206 words
A method for producing a polycrystalline translucent alumina sintered body in which the content of MgO is 0.001-0.04% by weight, the content of each La 2 O 3 and Y 2 O 3 is 0.001-0.01% by weight, a weight ratio of MgO/(La 2 O 3 +Y 2 O 3 ) is 0.5 to 2.0, and the translucent alumina sintered body has an in-line transmission of more than 40% at a wavelength of 0.6 μm, which comprises adding to alumina powder having a purity of more than 99.8%; MgO or a compound forming MgO, wherein a weight percent of MgO is within the range of 0.01-0.1%; La 2 O 3 or a compound forming La 2 O 3 , wherein a weight percent of La 2 O 3 is within the range 0.001-0.01%; and Y 2 O 3 or a compound forming Y 2 O 3 , wherein a weight percent of Y 2 O 3 is within the range 0.001-0.01%; thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under a vacuum or in either an atmosphere of hydrogen gas or dissociated ammonia gas, wherein an oxygen concentration is within a range of 10 -15 -10 -25 atm.
Claim 2
Independent Claim
206 words
A method for producing a polycrystalline translucent alumina sintered body in which the content of MgO is 0.001-0.04% by weight, the content of each La 2 O 3 and Y 2 O 3 is 0.001-0.01% by weight, a weight ratio of MgO/(La 2 O 3 +Y 2 O 3 ) is 0.5 to 2.0, and the translucent alumina sintered body has an in-line transmission of more than 40% at a wavelength of 0.6 μm, which comprises adding to alumina powder having a purity of more than 99.8%; MgO or a compound forming MgO, wherein a weight percent of MgO is within the range of 0.01-0.1%; La 2 O 3 or a compound forming La 2 O 3 , wherein a weight percent of La 2 O 3 is within the range 0.001-0.01%; and Y 2 O 3 or a compound forming Y 2 O 3 , wherein a weight percent of Y 2 O 3 is within the range 0.001-0.01%; thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under a vacuum or in either an atmosphere of hydrogen gas or dissociated ammonia gas, wherein an oxygen concentration is within a range of 10 -15 -10 -25 atm.
Claim 3
Dependent Claim
16 words
The method of claim 1, wherein said alumina powder has a grain size of 0.01-0.1 μm.
Claim 4
Dependent Claim
44 words
The method of claim 1, wherein said firing process is a 2-step firing process, wherein primary firing occurs within a temperature range of 1300°-1500° C. for 2-5 hours and secondary firing occurs within a temperature range of 1650°-1850° C. for at least one hour.
Claim 5
Dependent Claim
54 words
The method of claim 1, wherein said firing process is a 2-step process, wherein primary firing occurs within a temperature range of 1300°-1500° C., whereby temperature is raised at a rate of 25° C./hr within said primary firing and secondary firing occurs within a temperature range of 1650°-1850° C. for at least one hour.
References Cited (Backward Citations)
US3026210A
Cited
US3899560A
Cited
US3875277A
Cited
US4182972A
Cited
US4214666A
Cited
US4222978A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-22 | 1988-07-23 | 1989-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-22 | 1992-07-23 | 1993-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-22 | 1996-07-23 | 1997-01-22 | $7700.00 | Window Closed / Lapsed |