US4602956A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cermet composites, process for producing them and arc tube incorporating them
Assignee: Philips North America LLC
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Filing: 1984-12-17
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Granted: 1986-07-29
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Expires: 2004-12-17
Abstract
Abstract Composite cermets having a central core of a first cermet composition and one or more surrounding layers of different cermet compositions are formed by a multi-step pressing operation, followed by sintering. A tungsten/alumina or molybdenum/alumina composite cermet is useful as an end closure for alumina arc tubes of metal halide discharge lamps.
Inventors
- 👤 Deborah P. Partlow
- 👤 Shih-Ming Ho
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:54
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/36; H01J61/366; B; B22; B22F; B22F7/00; B22F7/06; C; C22; C22C; C22C29/00; C22C29/12; B22F2998/00; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/12028; Y10T428/12146; Y10T428/12493; Y10T428/12535; Y10T428/12729; Y10T428/12736; Y10T428/12743
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
47 words
A composite sintered cermet body comprising a core portion of a first cermet composition having a central axis, and one or more layers of other cermet compositions surrounding the core and substantially coaxial therewith, the top and bottom surfaces being substantially planar and normal to the axis.
Claim 2
Dependent Claim
47 words
A composite sintered cermet body comprising a core portion of a first cermet composition having a central axis, and one or more layers of other cermet compositions surrounding the core and substantially coaxial therewith, the top and bottom surfaces being substantially planar and normal to the axis.
Claim 3
Dependent Claim
19 words
The body of claim 1 in which the core is cylindrical, and the layers surrounding the core are annular.
Claim 4
Dependent Claim
34 words
The body of claim 1 in which the core and one or more layer compositions each comprise at least one refractory metal selected from the group consisting of tungsten and molybdenum and aluminum oxide.
Claim 5
Dependent Claim
53 words
The body of claim 3 in which the core consists essentially of from about 10 to 30 volume percent of said refractory metal, remainder aluminum oxide, and in which one layer surrounds the core, the layer consisting essentially of from about 5 to 10 volume percent of said refractory metal, remainder aluminum oxide.
Claim 6
Dependent Claim
34 words
The body of claim 4 in which the core consists essentially of about 20 volume percent tungsten, remainder aluminum oxide, and the layer consists essentially of about 71/2 volume percent tungsten, remainder aluminum oxide.
Claim 7
Dependent Claim
47 words
A composite sintered cermet body having a central axis, planar top and bottom surfaces normal to the axis, and an annular outer wall surrounding the axis, characterized in that the composition of the cermet changes substantially continuously, radially outward from the central axis to the outer wall.
Claim 8
Dependent Claim
47 words
A composite sintered cermet body having a central axis, planar top and bottom surfaces normal to the axis, and an annular outer wall surrounding the axis, characterized in that the composition of the cermet changes substantially continuously, radially outward from the central axis to the outer wall.
Claim 9
Dependent Claim
70 words
A process for producing a composite cermet body, comprising the steps of: (1) pressing a first cermet powder composition to form a powder compact having a central cavity opening into the top and bottom surfaces of the compact; (2) filling the cavity with a second cermet powder composition; (3) pressing the powder filled compact to form a green composite; and (4) sintering the composite to form an integral cermet body.
Claim 10
Dependent Claim
70 words
A process for producing a composite cermet body, comprising the steps of: (1) pressing a first cermet powder composition to form a powder compact having a central cavity opening into the top and bottom surfaces of the compact; (2) filling the cavity with a second cermet powder composition; (3) pressing the powder filled compact to form a green composite; and (4) sintering the composite to form an integral cermet body.
Claim 11
Dependent Claim
21 words
The process of claim 7 in which the compact is formed at a pressure of from about 500 to 1000 psi.
Claim 12
Dependent Claim
37 words
The process of claim 8 in which the green composite is formed by a two-step pressing, the first pressing step carried out at a relatively low pressure, and the second step carried out at a higher pressure.
Claim 13
Dependent Claim
40 words
The process of claim 9 in which the first pressing is carried out at a pressure of from about 500 to 1000 psi, and the second pressing is carried out at a pressure of from about 10,000 to 20,000 psi.
Claim 14
Dependent Claim
52 words
The process of claim 7 in which each cermet composition consists essentially of a refractory metal selected from the group consisting of tungsten and molybdenum, and aluminum oxide, and in which sintering is carried out in a non-oxidizing atmosphere at a temperature within the range of about 1500° C. to 1800° C.
Claim 15
Dependent Claim
42 words
The process of claim 8 in which depressions are formed in opposing surfaces of the core during the first pressing, electrical lead wires are embedded in the depressions during the second pressing, and the wires are bonded to the composite during sintering.
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) | 1989-07-28 | 1990-01-27 | 1990-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-28 | 1994-01-27 | 1994-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-28 | 1998-01-27 | 1998-07-29 | $7700.00 | Window Closed / Lapsed |