US4929574A
Expired / Lapsed
US
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Electromagnetic wave absorbers comprised of barium titanate powders
Assignee: Rhodia Chimie SAS
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Filing: 1989-03-30
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Granted: 1990-05-29
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Expires: 2009-03-30
Abstract
Abstract Novel compositions containing finely divided barium titanate particulates homogeneously dispersed in a solid organic matrix material, the barium titanate particles having a mean diameter of at least 1 micron, are well adopted for the production of electromagnetic wave absorbers, e.g., seals for microwave ovens.
Inventors
- 👤 Alain Iltis
- 👤 Patrick Maestro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:22
CPC Classifications
C; C08; C08K; C08K3/00; C08K3/18; C08K3/24; C09; C09C; C09C1/00; C09C1/36; H; H01; H01Q; H01Q17/00; H01Q17/004; H05; H05B; H05B6/00; H05B6/64; H05B6/76; C01; C01P; C01P2004/00; C01P2004/60; C01P2004/61
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
56 words
A composition of matter comprising an electromagnetic wave absorbing amount of finely divided barium titanate particulates homogeneously dispersed in a solid organic matrix material, the mean diameter of such barium titanate particulates being equal to or greater than 1 micron at least 50% by volume of such barium titanate particulates being in the quadratic crystalline state.
Claim 2
Dependent Claim
56 words
A composition of matter comprising an electromagnetic wave absorbing amount of finely divided barium titanate particulates homogeneously dispersed in a solid organic matrix material, the mean diameter of such barium titanate particulates being equal to or greater than 1 micron at least 50% by volume of such barium titanate particulates being in the quadratic crystalline state.
Claim 3
Dependent Claim
26 words
The composition of matter as defined by claim 1, wherein the mean diameter of such barium titanate particulates is equal to or greater than 10 microns.
Claim 4
Dependent Claim
26 words
The composition of matter as defined by claim 2, wherein the mean diameter of such barium titanate particulates is equal to or greater than 100 microns.
Claim 5
Dependent Claim
29 words
The composition of matter as defined by claim 2, said barium titanate particulates comprising aggregates of elementary crystals having a mean diameter equal to or greater than 1 micron.
Claim 6
Dependent Claim
26 words
The composition of matter as defined by claim 1, wherein at least 90% by volume of such barium titanate particulates being in the quadratic crystalline state.
Claim 7
Dependent Claim
24 words
The composition of matter as defined by claim 1, wherein the molar Ba/Ti ratio in such barium titanate particulates is slightly greater than 1.
Claim 8
Dependent Claim
26 words
The composition of matter as defined by claim 1, wherein the barium titanate particulates comprise less than or equal to 1% by weight of strontium values.
Claim 9
Dependent Claim
23 words
The composition of matter as defined by claim 7, wherein the barium titanate particulates comprise less than 0.1% by weight of strontium values.
Claim 10
Dependent Claim
31 words
The composition of matter as defined by claim 1, wherein the ratio by volume of the barium titanate particulates to the total volume of the composition ranges from 15% to 60%.
Claim 11
Dependent Claim
16 words
The composition of matter as defined by claim 9, said ratio ranging from 15% to 35%.
Claim 12
Dependent Claim
37 words
A process for the preparation of finely divided barium titanate particulates having a mean diameter of at least 1 micron, comprising heat treating a submicronic barium titanate powder at a temperature of from 1,100° to 1,600° C.
Claim 13
Dependent Claim
37 words
A process for the preparation of finely divided barium titanate particulates having a mean diameter of at least 1 micron, comprising heat treating a submicronic barium titanate powder at a temperature of from 1,100° to 1,600° C.
Claim 14
Dependent Claim
18 words
The process as defined by claim 11, carried out at a temperature of from 1,150° to 1,350° C.
Claim 15
Dependent Claim
16 words
The process as defined by claim 12, carried out at a temperature of about 1,250° C.
Claim 16
Dependent Claim
14 words
The process as defined by claim 11, further carried out in an air atmosphere.
Claim 17
Dependent Claim
31 words
The process as defined by claim 11, carried out in the presence of an affective amount of a lithium salt additive to promote the crystalline growth of the barium titanate particulates.
Claim 18
Dependent Claim
13 words
The process as defined by claim 15, said lithium salt comprising lithium fluoride.
Claim 19
Dependent Claim
14 words
An electromagnetic wave absorber comprising the composition of matter as defined by claim 1.
Claim 20
Dependent Claim
15 words
The electromagnetic wave absorber as defined by claim 17, comprising a seal for microwave ovens.
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) | 1993-05-28 | 1993-11-27 | 1994-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-28 | 1997-11-27 | 1998-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-28 | 2001-11-27 | 2002-05-29 | $7700.00 | Window Closed / Lapsed |