US5099174A
Expired / Lapsed
US
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Arc tube for a discharge lamp
Assignee: EMI Group Ltd
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Filing: 1989-07-12
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Granted: 1992-03-24
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Expires: 2009-07-12
Abstract
Abstract A sealing composition is provided for joining crystalline ceramic or cermet parts, e.g. in an arc tube for a discharge lamp. The sealing composition comprises, as starting materials, a mixture of alumina (Al 2 ,O 3 ), silica (SiO 2 ) and magnesia (MgO), the mixture comprising in the ranges of from 22% to 24.5% by weight of Al 2 O 3 , from 45.5% to 49.5% by weight of SiO 2 , and from 26.0% to 32.5% by weight of MgO. The sealing composition contains less than 40% by weight, of the mixture, of the crystalline phase α-Cordierite when subjected to the following test procedure. (i) sintering the mixture at 1200° C. for 10 hours to produce a friable lump which is crunched and heated at 1550° C. for 2 hours while the glass is in a molten condition; (ii) pouring the resulting material into water to form a brittle frit and, after drying at 160° C., grinding the glass to a powder particle less than 180 μm; (iii) mixing the glass with 4% by weight of a solution in toluene of methyl/butyl methacrylate, and pressing the mixture in a 16 mm diameter die at 100 MPa to produce 1 g samples; (iv) sintering a sample continuously for 6 hours at a temperature equal to or greater than the temperature a seal made from the sealing composition is intended to withstand; and (v) evaluating the proportion by weight of the crystalline phase α-Cordierite in the samples sintered at the sintering temperature.
Inventors
- 👤 George E. Coxon
- 👤 Peter Hing
- 👤 Keith E. Parker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:10
CPC Classifications
C; C04; C04B; C04B37/00; C04B37/02; C04B37/023; C04B37/025; C03; C03C; C03C10/00; C03C10/0036; C03C10/0045; C03C8/00; C03C8/24; C04B2237/00; C04B2237/02; C04B2237/04; C04B2237/06; C04B2237/062; C04B2237/30; C04B2237/32; C04B2237/34; C04B2237/343; C04B2237/40; C04B2237/401; C04B2237/50; C04B2237/76; C04B2237/765
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
306 words
A sealing composition for joining crystalline ceramic or cermet parts, the sealing composition comprising, as starting materials, a mixture of alumina (Al 2 O 3 ), silica (SiO 2 ) and magnesia (MgO), the mixture comprising in the ranges of from 22% to 24.5% by weight of Al 2 O 3 , from 45.5% to 49.5% by weight of SiO 2 , and from 26.0% to 32.5% by weight of MgO; the sealing composition containing less than 40% by weight, expressed as the percentage of the total weight of the mixture, of the crystalline phase α-Cordierite when subjected to a test procedure comprising the following steps: (i) thoroughly mixing the constituents of the sealing composition and sintering the mixture at 1200° C. for 10 hours to produce a friable lump which is crushed, transferred to a platinum crucible with 10% Rhodium, and heated in a muffle furnace at 1550° C. for 2 hours while the glass is in a molten condition; (ii) pouring the contents of the crucible into distilled water to form a brittle frit or cullet and, after drying at 160° C., grinding the glass in an Agate Cone Grinder to form a powder of particle size less than 180 μm; (iii) mixing the powdered glass with 4% by weight of a binder comprising a solution in toluene of methyl/butyl methacrylate, and pressing the mixture in a 16 mm diameter die at 100 MPa to produce lg samples; (iv) sintering a sample continuously for 6 hours at a sintering tempterature equal to or greater than the temperature a seal made from the sealing composition is intended to withstand; and (v) evaluating, by X-ray Diffractometry, the proportion by weight, expressed as a percentage of the total weight of alumina, silica and magnesia, of the crystalline phase α-Cordierite in the sample sintered at the sintering temperature.
Claim 2
Dependent Claim
306 words
A sealing composition for joining crystalline ceramic or cermet parts, the sealing composition comprising, as starting materials, a mixture of alumina (Al 2 O 3 ), silica (SiO 2 ) and magnesia (MgO), the mixture comprising in the ranges of from 22% to 24.5% by weight of Al 2 O 3 , from 45.5% to 49.5% by weight of SiO 2 , and from 26.0% to 32.5% by weight of MgO; the sealing composition containing less than 40% by weight, expressed as the percentage of the total weight of the mixture, of the crystalline phase α-Cordierite when subjected to a test procedure comprising the following steps: (i) thoroughly mixing the constituents of the sealing composition and sintering the mixture at 1200° C. for 10 hours to produce a friable lump which is crushed, transferred to a platinum crucible with 10% Rhodium, and heated in a muffle furnace at 1550° C. for 2 hours while the glass is in a molten condition; (ii) pouring the contents of the crucible into distilled water to form a brittle frit or cullet and, after drying at 160° C., grinding the glass in an Agate Cone Grinder to form a powder of particle size less than 180 μm; (iii) mixing the powdered glass with 4% by weight of a binder comprising a solution in toluene of methyl/butyl methacrylate, and pressing the mixture in a 16 mm diameter die at 100 MPa to produce lg samples; (iv) sintering a sample continuously for 6 hours at a sintering tempterature equal to or greater than the temperature a seal made from the sealing composition is intended to withstand; and (v) evaluating, by X-ray Diffractometry, the proportion by weight, expressed as a percentage of the total weight of alumina, silica and magnesia, of the crystalline phase α-Cordierite in the sample sintered at the sintering temperature.
Claim 3
Dependent Claim
25 words
A sealing composition according to claim 1, the sealing composition consisting only of the mixture of Al 2 O 3 , SiO 2 and MgO.
Claim 4
Dependent Claim
20 words
A sealing composition according to claim 1 the sealing composition consisting of the mixture and up to 5% of additive.
Claim 5
Dependent Claim
15 words
A sealing composition according to claim 3 wherein the additive comprises titania (TiO 2 ).
Claim 6
Dependent Claim
18 words
A sealing composition according to claim 1 wherein the sintering temperature in the test procedure is 1000° C.
Claim 7
Dependent Claim
42 words
A sealing composition according to claim 5 wherein the mixture comprises silica, alumina and magnesia in proportions such that the mixture falls within the region enclosed by line E in the ternary phase diagram shown in FIG. 2 of the accompanying drawings.
Claim 8
Dependent Claim
33 words
A sealing composition according to claim 6 wherein the mixture consists of 22.9% by weight of Al 2 O 3 , 46.3% by weight of SiO 2 and 30.8% by weight of MgO.
Claim 9
Dependent Claim
33 words
A sealing composition according to claim 6 wherein the mixture consists of 24% by weight of Al 2 O 3 , 49.0% by weight of SiO 2 and 27.0% by weight of MgO.
Claim 10
Dependent Claim
33 words
A sealing composition according to claim 6 wherein the mixture consists of 23.0% by weight of Al 2 O 3 , 48.0% by weight of SiO 2 and 29.0% by weight of MgO.
Claim 11
Dependent Claim
40 words
An arc tube for a discharge lamp, the arc tube comprising an envelope of crystalline ceramic material and one or more end closures hermetically sealed to the envelope by a sealing composition according to any one of the preceding claims.
Claim 12
Dependent Claim
27 words
An arc tube according to claim 10 wherein the envelope is made of a material selected from the group consisting of polycrystalline alumina, sapphire and a spinel.
Claim 13
Dependent Claim
65 words
An arc tube for a discharge lamp, the arc tube comprising an envelope of crystalline ceramic material and one or more end closures hermetically sealed to the envelope by a seal formed from a sealing composition comprising, as starting materials, a mixture of Al 2 O 3 , SiO 2 and MgO, the seal containing less than 40% by weight of a crystalline phase α-Cordierite.
Claim 14
Dependent Claim
65 words
An arc tube for a discharge lamp, the arc tube comprising an envelope of crystalline ceramic material and one or more end closures hermetically sealed to the envelope by a seal formed from a sealing composition comprising, as starting materials, a mixture of Al 2 O 3 , SiO 2 and MgO, the seal containing less than 40% by weight of a crystalline phase α-Cordierite.
Claim 15
Dependent Claim
27 words
An arc tube according to claim 12 wherein the envelope is made of a material selected from the group consisting of polycrystalline alumina, sapphire and a spinel.
References Cited (Backward Citations)
GB1109821A
Cited
US3940255A
Cited
GB1544779A
Cited
DE2812859A1
Cited
EP0055049A1
Cited
US4694219A
Cited
JPS59219850A
Cited
EP0220813A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-24 | 1995-09-23 | 1996-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-24 | 1999-09-23 | 2000-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-24 | 2003-09-23 | 2004-03-24 | $7700.00 | Window Closed / Lapsed |