Hsiao J Cheng

US Patent:

44394683, Mar 27, 1984

Filed:

Aug 25, 1982

Appl. No.:

6/412366

Inventors:

Anthony Liang - Belmont CA
Hsiao L. Cheng - Sunnyvale CA

Assignee:

GTE Products Corporation - Stamford CT

International Classification:

C09D 524
C23C 302
B22F 102

US Classification:

427216

Abstract:

A metallic powder having a core of silver and an outer layer of platinum wherein the silver is from about 90 to about 99. 5% by weight of the total composition. A process for producing such a powder comprising forming a first aqueous slurry of silver powder, an appropriate amount of lignosulfonate ammonia and water, forming a second slurry of platinum as a platinum-ammonium complex dispersed in a water soluble alkanol, mixing the first and second slurry, adjusting the pH of the mixture to a range of from about 8 to about 10, adding an appropriate amount of hydrazine to the mixture maintaining the resultant slurry at about 40. degree. C. to 60. degree. C. for an appropriate time to coat the platinum onto the silver, then separating the platinum-coated silver powder from the remainder of the slurry.