Production of composite structures

• US 6,231,792 B1
• Filed: 08/07/1998
• Issued: 05/15/2001
• Est. Priority Date: 08/08/1997
• Status: Expired due to Term

• Current Assignee: ABB Lummus Global Inc. (ABB Limited)
• Original Assignee: ABB Lummus Global Inc. (ABB Limited)
• Inventors: Tatarchuk, Bruce J., Meffert, Michael W., Chang, Yung-Feng, Murrell, Lawrence L., Overbeek, Rudolf A., Khonsari, Ali M.
• Primary Examiner(s): Fiorilla, Christopher A.
• Application Number:
  US09/131,151
• Time in Patent Office: 1,012 Days
• Field of Search: 264/43, 264/44, 264/628, 264/640, 419/2
• US Class Current: 264/43
• CPC Class Codes: B01J 2208/00884 Means for supporting the bed of particles, e.g. grids, bars, perforated plates
• CPC Class Codes: B01J 35/58 Fabrics or filaments
• CPC Class Codes: B22F 3/002 Manufacture of articles essentially made from metallic fibres
• CPC Class Codes: B22F 3/1121 by using decomposable, meltable or sublimatable fillers
• CPC Class Codes: C04B 14/386 Carbon carbon nanotubes C04B14/026
• CPC Class Codes: C04B 14/46 Rock wool ; Ceramic or silicate fibres C04B14/40, C04B14/42 take precedence
• CPC Class Codes: C04B 14/48 Metal
• CPC Class Codes: C04B 2111/0081 as catalysts or catalyst carriers
• CPC Class Codes: C04B 24/383 Cellulose or derivatives thereof
• CPC Class Codes: C04B 30/02 containing fibrous materials
• CPC Class Codes: C04B 38/0675 Vegetable refuse; Cellulosic materials, e.g. wood chips, cork, peat, paper
• CPC Class Codes: C04B 40/0263 Hardening promoted by a rise in temperature C04B40/024 takes precedence
• CPC Class Codes: C04B 40/0268 Heating up to sintering temperatures C04B41/0072 takes precedence

Abstract

A porous composite product comprised of a network of fibers is produced by forming an unsintered preformed network of fibers and a gasifiable structure forming agent, followed by gasification of the structure forming agent prior to sintering of the fibers at appropriate junction points. The preferred structure forming agent is a cellulosic material.

Claims

1. A process for producing a porous product comprising a network of fibers, comprising:

producing a preform comprising an unsintered network of fibers and a gasifiable structure forming agent;

in a first step, gasifying, in the presence of oxygen and steam, at least 50% of the structure forming agent by heating and maintaining the preform at a gasification temperature for a time sufficient to gasify at least 50% of the structure forming agent, said gasification temperature being a temperature below the temperature at which the fibers are sintered; and

in a second step, sintering fibers of the preform by maintaining the preform resulting from said first step at a sintering temperature for a period of time sufficient to sinter said fibers at at least a portion of junction points of the fibers, said sintering temperature being higher than said gasification temperature.

2. The process of claim 1, wherein the structure forming agent is a cellulosic material.

3. The process of claim 2 wherein the fibers are metal fibers.

4. The process of claim 1 wherein the gasifying is effected at a temperature of less than 400°

C.

5. The process of claim 1 wherein at least 70% of the structure forming agent is gasified at said gasification temperature.

6. The process of claim 5 wherein at least 90% of the structure forming agent is gasified at said gasification temperature.

7. The process of claim 1 wherein the fibers are at least one member selected from the group consisting of metal fibers, ceramic fibers and carbon fibers.

8. A process for producing a porous product comprising a network of metal fibers, comprising:

producing a preform comprising an unsintered network of metal fibers and a gasifiable structure forming agent, said structure forming agent being formed of a cellulosic material, and wherein said preform has particles of a catalyst support retained in the interstices of said fiber network, and wherein said catalyst support supports a catalyst or catalyst precursor;

in a first step, gasifying at least 50% of the structure forming agent by heating and maintaining the preform at a gasification temperature for a time sufficient to gasify at least 50% of the structure forming agent, said gasification temperature being a temperature below the temperature at which the fibers are sintered; and

in a second step, sintering fibers of the preform by maintaining the preform resulting from said first step at a sintering temperature for a period of time sufficient to sinter said fibers at at least a portion of junction points of the fibers, said sintering temperature being higher than said gasification temperature.

9. The process of claim 8 wherein the gasifying is effected in the presence of oxygen and steam.

10. The process of claim 8 wherein the gasifying is effected at a temperature of less than 400°

C.

11. The process of claim 8 wherein at least 70% of the structure forming agent is gasified at said gasification temperature.

12. The process of claim 11 wherein at least 90% of the structure forming agent is gasified at said gasification temperature.