Patent US4952935A successfully refreshed from Google Patents.
US4952935A
Expired / Lapsed
US
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Radiowave absorber and its manufacturing process
Assignee: Shinwa International Co Ltd
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Filing: 1988-10-26
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Granted: 1990-08-28
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Expires: 2008-10-26
Abstract
Abstract A radiowave absorber comprises a porous ceramic matrix combined with carbon, where the carbon is combined on its surface and interior particularly in an amount not exceeding 2.7% by weight. A process for manufacturing a radiowave absorber is also disclosed. At least one kind of ceramic material selected from natural minerals or clay minerals, and artificial ceramic materials, is fired with a pore- or skeleton-forming material which can be burned away, whereby a sintered porous ceramic matrix is prepared. The matrix is fired in a furnace containing a reducing atmosphere and having a uniform temperature, while a gas or mist of hydrocarbon compound is introduced into the furnace.
Inventors
- 👤 Shinnosuke Sawa
- 👤 Shunichi Kumaoka
- 👤 Teruo Ohno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:54
CPC Classifications
H; H05; H05K; H05K9/00; H05K9/0073; H05K9/0081; H05K9/0083
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
87 words
A process for manufacturing a radiowave absorber comprising: the first process of firing at least one kind of ceramic material with a pore- or skeleton-forming material which can be burned away, whereby a sintered porous ceramic matrix is prepared, said ceramic material being selected from natural minerals and clay minerals and artificial ceramic materials; and the second process of firing said matrix in a furnace containing a reducing atmosphere and having a uniform temperature, while introducing a gas or mist of a hydrocarbon compound into said furnace.
Claim 2
Dependent Claim
87 words
A process for manufacturing a radiowave absorber comprising: the first process of firing at least one kind of ceramic material with a pore- or skeleton-forming material which can be burned away, whereby a sintered porous ceramic matrix is prepared, said ceramic material being selected from natural minerals and clay minerals and artificial ceramic materials; and the second process of firing said matrix in a furnace containing a reducing atmosphere and having a uniform temperature, while introducing a gas or mist of a hydrocarbon compound into said furnace.
Claim 3
Dependent Claim
34 words
A process as set forth in claim 1, wherein said hydrocarbon compound is introduced into said furnace for a period of 6 to 65 minutes continuously when said temperature is higher than 500° C.
Claim 4
Dependent Claim
32 words
A process as set forth in claim 1, further including crushing said matrix into a powdery or granular form after combining carbon with porous ceramic matrix in the first and second processes.
Claim 5
Dependent Claim
36 words
A process as set forth in claim 1, further including crushing said matrix into a powdery or granular form after crushing the sintered porous ceramic matrix into a powdery or granular form in the first process.
Claim 6
Dependent Claim
109 words
A process for manufacturing a radiowave absorber comprising: a first process of firing at least one kind of ceramic material with a pore- or skeleton-forming material which can be burned away, whereby a sintered, porous, ceramic matrix is prepared, said ceramic material being selected from the group consisting of natural minerals, clay minerals, and artificial ceramic materials; and a second process of firing said matrix in a furnace containing a reducing atmosphere and having an uniform temperature, while introducing a gas or mist of a hydrocarbon into said furnace for a period of 6 to 65 minutes, substantially continuously, and wherein said furnace temperature is greater than 500° C.
Claim 7
Dependent Claim
109 words
A process for manufacturing a radiowave absorber comprising: a first process of firing at least one kind of ceramic material with a pore- or skeleton-forming material which can be burned away, whereby a sintered, porous, ceramic matrix is prepared, said ceramic material being selected from the group consisting of natural minerals, clay minerals, and artificial ceramic materials; and a second process of firing said matrix in a furnace containing a reducing atmosphere and having an uniform temperature, while introducing a gas or mist of a hydrocarbon into said furnace for a period of 6 to 65 minutes, substantially continuously, and wherein said furnace temperature is greater than 500° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-27 | 1994-02-26 | 1994-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-27 | 1998-02-26 | 1998-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-27 | 2002-02-26 | 2002-08-28 | $7700.00 | Window Closed / Lapsed |