Nonwoven metal fabric and method of making same

• US 6,585,794 B2
• Filed: 10/26/2001
• Issued: 07/01/2003
• Est. Priority Date: 11/07/2000
• Status: Expired due to Term

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Tsubouchi, Toshiyasu, Shimoda, Kohei
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): Pham, Minh Chau Thi
• Application Number:
  US09/983,872
• Publication Number:
  US 20020078669A1
• Time in Patent Office: 613 Days
• Field of Search: 555/22, 555/25, 555/27, 555/28, 55D/IG.5, 553/853, 264/DIG.48, 210/500.25, 428/608, 428/613, 123/198.E, 442/117, 442/376, 442/377, 442/378, 442/379
• US Class Current: 55/527
• CPC Class Codes: B01D 39/2086 sintered or bonded by inorganic agents
• CPC Class Codes: B22F 1/062 Fibrous particles
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/002 Manufacture of articles essentially made from metallic fibres
• CPC Class Codes: B22F 9/16 using chemical processes
• CPC Class Codes: C25D 1/08 Perforated or foraminous objects, e.g. sieves C25D1/10 takes precedence
• CPC Class Codes: C25D 5/50 by heat-treatment
• CPC Class Codes: C25D 7/00 Electroplating characterised by the article coated
• CPC Class Codes: D04H 1/4234 Metal fibres
• CPC Class Codes: D04H 1/43838 Ultrafine fibres, e.g. microfibres
• CPC Class Codes: D04H 1/43912 fibres with noncircular cross-sections
• CPC Class Codes: D04H 1/70 characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
• CPC Class Codes: F01N 2330/12 Metallic wire mesh fabric or knitting
• CPC Class Codes: F01N 3/022 characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10S 264/48 Processes of making filters
• CPC Class Codes: Y10S 55/05 Methods of making filter
• CPC Class Codes: Y10T 428/12444 Embodying fibers interengaged or between layers [e.g., paper, etc.]
• CPC Class Codes: Y10T 428/12479 Porous [e.g., foamed, spongy, cracked, etc.]
• CPC Class Codes: Y10T 442/2475 Coating or impregnation is electrical insulation-providing, -improving, or -increasing, or conductivity-reducing
• CPC Class Codes: Y10T 442/654 : Including a free metal or alloy constituent
• CPC Class Codes: Y10T 442/655 : Metal or metal-coated strand or fiber material
• CPC Class Codes: Y10T 442/656 : Preformed metallic film or foil or sheet [film or foil or sheet had structural integrity prior to association with the nonwoven fabric]
• CPC Class Codes: Y10T 442/657 : Vapor, chemical, or spray deposited metal layer

Abstract

The present invention provides a nonwoven metal fabric for various uses, such as a filter used for purification of exhaust gas from automobiles or semiconductor manufacturing gas, a catalyst carrier of fuel cell, and so forth, in which the corrosion resistance is improved without compromising the property in terms of pressure loss. The nonwoven metal fabric of the present invention is formed with the metal fibers wherein the relation of the fiber diameter Da at the surface part of the gas inlet side and the fiber diameter Db at the central part of the thickness direction is expressed as the equation Da≧1.5×Db and the fiber diameter Da at the surface part of the gas inlet side is not less than 15 μm and not more than 60 μm.

Claims

1. A nonwoven metal fabric formed with mainly metal fibers, wherein:

the fiber diameter Da at the surface part of the gas inlet side and the fiber diameter Db at the central part of the thickness direction satisfy the equation Da≧

1.5×

Db;

and the fiber diameter Da at the surface part of the gas inlet side is not less than 15 μ

m and not more than 60 μ

m.

2. A nonwoven metal fabric according to claim 1, wherein the fiber diameter Db at the central part of the thickness direction is not less than 35 μ

m.

3. A nonwoven metal fabric according to claim 1, wherein the cross-section of the metal fiber is not angular.

4. A nonwoven metal fabric according to claim 1, wherein the main composition of the metal fiber is Fe or Ni, or both.

5. A method of making a nonwoven metal fabric, comprising the steps of:

electroplating the surface of a conductive nonwoven fabric with metal under the conditions where the maximum current density is not less than 10 A/dm² and the metal concentration in a plate bath is not more than 120 g/L,; and

sintering the resultant product in a reducing atmosphere, thereby removing the conductive nonwoven fabric therefrom.

6. A method of making a nonwoven metal fabric according to claim 5, wherein said conductive nonwoven fabric is a carbon nonwoven fabric or an organic fiber nonwoven fabric whose surface is treated to have conductivity.

7. A method of making a nonwoven metal fabric according to claim 5, wherein the thickness of said conductive nonwoven fabric is not less than 0.3 mm.