Method of making flowable tungsten/copper composite powder

• US 5,439,638 A
• Filed: 07/16/1993
• Issued: 08/08/1995
• Est. Priority Date: 07/16/1993
• Status: Expired due to Term

• Current Assignee: Cytosorbents Corporation
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Sampath, Sanjay, Houck, David L., Paliwal, Muktesh, Kopatz, Nelson
• Primary Examiner(s): Walsh, Donald P.
• Assistant Examiner(s): BLUNI, SCOTT
• Application Number:
  US08/092,727
• Time in Patent Office: 753 Days
• Field of Search: 419/30, 419/33, 75/343
• US Class Current: 419/30
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 9/026 Spray drying of solutions or suspensions
• CPC Class Codes: C22C 1/045 Alloys based on refractory metals
• CPC Class Codes: H01H 1/025 having copper as the basic material
• CPC Class Codes: H01L 23/3736 Metallic materials H01L23/3732, H01L23/3733, H01L23/3735, H01L23/3737, H01L23/3738 take precedence
• CPC Class Codes: H01L 23/4924 characterised by the materials
• CPC Class Codes: H01L 23/49883 the conductive materials containing organic materials or pastes, e.g. for thick films for printed circuits H05K1/092
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method of making flowable tungsten/copper composite powder by milling an aqueous slurry of a mixture of the desired weight ratio of tungsten powder and copper oxide powder and, optionally, a small amount of cobalt powder, spray-drying the slurry to form spherical, flowable agglomerates, and reducing the agglomerates in a hydrogen atmosphere.

Claims

1. A method of making a flowable tungsten/copper composite powder suitable for pressing and sintering and containing between 5 and 60 weight percent copper and the balance tungsten, comprising the steps of:

a) forming a uniform mixture of a desired weight ratio of tungsten powder, copper oxide powder and, optionally, less than 0.5 weight percent cobalt powder;

b) milling said mixture in an aqueous medium to cause an exothermic reaction between said aqueous medium, said tungsten powder and said copper oxide powder, said milling further acting to form a slurry in which said tungsten and copper oxide powders are intimately mixed, said slurry being maintained at a temperature between about 25°

C. to about 35°

C. to control said exothermic reaction;

c) removing the liquid from said slurry to form spherical, flowable agglomerates; and

d) subjecting said spherical, flowable agglomerates to a reducing atmosphere to form said flowable tungsten/copper composite powder.

2. A method according to claim 1 wherein said flowable tungsten/copper composite powder contains 15 weight percent copper and the balance tungsten.

3. A method according to claim 1 wherein said mixture is attritor milled in water for 6 hours at a temperature of 30°

C.

4. A method according to claim 1 wherein said liquid is removed from said slurry by spray drying said slurry.

5. A method according to claim 1 wherein said spherical, flowable agglomerates are reduced in a hydrogen atmosphere at 715°

C. for 1 hour.