Incombustible honeycomb radio absorptive material and radio absorber using the same

• US 6,217,978 B1
• Filed: 08/27/1999
• Issued: 04/17/2001
• Est. Priority Date: 08/28/1998
• Status: Expired due to Term

• Current Assignee: TDK Corporation, Tokiwa Electric, Co.
• Original Assignee: TDK Corporation, Tokiwa Electric, Co.
• Inventors: Kurihara, Hiroshi, Sato, Naoyoshi, Murase, Taku, Hayashi, Kozo, Fujimoto, Kyoichi, Yanagawa, Motonari, Saitoh, Toshifumi
• Primary Examiner(s): Lorin, Francis J.
• Application Number:
  US09/384,383
• Time in Patent Office: 599 Days
• Field of Search: 428/116, 428/118, 342/1
• US Class Current: 428/116
• CPC Class Codes: H01Q 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• CPC Class Codes: H01Q 17/008 with a particular shape H01Q17/007 takes precedence
• CPC Class Codes: H05K 9/0003 Shielded walls, floors, ceilings, e.g. wallpaper, wall panel, electro-conductive plaster, concrete, cement, mortar
• CPC Class Codes: Y10T 428/24149 Honeycomb-like

Abstract

An incombustible honeycomb radio absorptive material is disclosed, forming a honeycomb structure that is an aggregate of many cells, wherein (i) the honeycomb structure contains a hydrated inorganic compound and an electrically conductive material, or (ii) the honeycomb structure contains a hydrated inorganic compound and has an electrically conductive layer made of an electrically conductive material being formed on the surface of the structure. A radio absorber is also disclosed, wherein a large number of the incombustible honeycomb radio absorptive materials are disposed on a shield panel or a ferrite tile covering he shield panel is provided. The incombustible honeycomb radio absorptive material and the radio absorber using it according to the invention are suitably used for an anechoic chamber and are excellent in the fire resistance and the radio absorption effect.

Claims

1. An incombustible honeycomb radio absorptive material forming a honeycomb structure that is an aggregate of many cells, wherein said honeycomb structure contains a hydrated inorganic compound and an electrically conductive material.

2. The incombustible honeycomb radio absorptive material according to claim 1, wherein the content of the electrically conductive material is 0.5-30 g/l in the total volume (the total volume including cell spaces) of the honeycomb structure.

3. The incombustible honeycomb radio absorptive material according to claim 1, wherein the content of the hydrated inorganic compound is 50-90 wt % in the total weight of the honeycomb structure.

4. The incombustible honeycomb radio absorptive material according to claim 1, wherein the size of each cell is 5-60 mm and a thickness of the honeycomb structure is 10-50 mm.

5. The incombustible honeycomb radio absorptive material according to claim 1, wherein the incombustible honeycomb radio absorptive material is obtainable by manufacturing wet sheets from a slurry containing the hydrated inorganic compound and the electrically conductive material, then drying and solidifying the wet sheets to form sheets, followed by laminating said sheets in a honeycomb form.

6. The incombustible honeycomb radio absorptive material according to claim 5, wherein the slurry further contains inorganic fibers as a reinforcing material.

7. The incombustible honeycomb radio absorptive material according to claim 5, wherein the sheets are plural-layered, and a glass cloth is sandwiched between each sheet layers.

8. The incombustible honeycomb radio absorptive material according to claim 1, wherein the hydrated inorganic compound is at least one member selected from sepiolite;

a hydrate of aluminum hydroxide, magnesium hydroxide, or calcium hydroxide;

gypsum dihydrate, calcium aluminate hydrate, and wollastonite.

9. The incombustible honeycomb radio absorptive material according to claim 8, wherein the hydrated inorganic compound is sepiolite.

10. The incombustible honeycomb radio absorptive material according to claim 1, wherein an incombustible sheet material is stuck to at least one surface of the honeycomb structure.

21. A radio absorber wherein a large number of the incombustible honeycomb radio absorptive materials as recited in either claim 1 or claim 11 are disposed on a shield panel or a ferrite tile covering the shield panel.

22. The radio absorber according to claim 21, wherein the incombustible honeycomb radio absorptive material each is formed in a hollowed square pyramid form or a hollowed wedge form, and the thusly formed materials are disposed on a shield panel or a ferrite tile covering the shield panel.

11. An incombustible honeycomb radio absorptive material forming a honeycomb structure that is an aggregate of many cells, wherein said honeycomb structure contains a hydrated inorganic compound, and has an electrically conductive layer made of an electrically conductive material formed on the surface of the honeycomb structure.

12. The incombustible honeycomb radio absorptive material according to claim 11, wherein the content of the electrically conductive material is 0.5-30 g/l in the total volume (the total volume including cell spaces) of the honeycomb structure.

13. The incombustible honeycomb radio absorptive material according to claim 11, wherein the content of the hydrated inorganic compound is 50-90 wt % in the total weight of the honeycomb structure.

14. The incombustible honeycomb radio absorptive material according to claim 11, wherein the size of each cell is 5-60 mm and a thickness of the honeycomb structure is 10-50 mm.

15. The incombustible honeycomb radio absorptive material according to claim 11, wherein the incombustible honeycomb radio absorptive materila is obtainable by manufacturing wet sheets from a slurry containing the hydrated inorganic compound, then drying and solidifying the wet sheets to form sheets, followed by laminating said sheets in a honeycomb form.

16. The incombustible honeycomb radio absorptive material according to claim 11, wherein the slurry further contains inorganic fibers as a reinforcing material.

17. The incombustible honeycomb radio absorptive material according to claim 11, wherein the sheets are plural-layered, and a glass cloth is sandwiched between each sheet layers.

18. The incombustible honeycomb radio absorptive material according to claim 11, wherein the hydrated inorganic compound is at least one member selected from sepiolite;

a hydrate of aluminum hydroxide, magnesium hydroxide, or calcium hydroxide;

gypsum dihydrate, calcium aluminate hydrate, and wollastonite.

19. The incombustible honeycomb radio absorptive material according to claim 18, wherein the hydrated inorganic compound is sepiolite.

20. The incombustible honeycomb radio absorptive material according to claim 11, wherein an incombustible sheet material is stuck to at least one surface of the honeycomb structure.