Dispersion strengthened silver

Abstract

The invention provides a fully dense compacted metal composite comprising silver alloy matrix having uniformly dispersed therein discrete microparticles of a refractory metal oxide, and further comprising discrete macroparticles of metal oxides. This composition can be used for electrical contacts which have greater mechanical strength, welding resistance and arc erosion resistance than previously known electrical contacts.

What is claimed:  
     
         1 . A fully dense compacted powdered silver composite comprising (a) a silver or silver alloy matrix having uniformly dispersed therein discrete microparticles of a refractory metal oxide and (b) discrete macroparticles of a metal oxide selected from the group consisting of tin oxide (SnO 2 ), cobalt oxide (Co 3 O 4 ), molybdenum oxide (MO 3 ), tungsten oxide (WO 3 ) and zinc oxide (ZnO).  
     
     
         2 . The metal composite of  claim 1  wherein the refractory metal oxide is aluminum oxide.  
     
     
         3 . The metal composite of  claim 1  wherein the metal oxides are selected from the group of tin oxide, cobalt oxide, molybdenum oxide, tungsten oxide and zinc oxide.  
     
     
         4 . The metal composite of  claim 2  wherein the concentration of aluminum oxide in the matrix is in the weight range of from 0.2% to about 1.1%  
     
     
         5 . The metal composite of  claim 1  wherein the concentration of the metal oxide is in the weight range of from 1% to 15%.  
     
     
         6 . A method of making a dispersion strengthened silver composite containing macroparticles of a metal oxide comprising the steps of: 
 a. providing a powdered metal alloy of silver and a refractory oxide forming solute metal;    b. internally oxidizing said solute metal by heating said alloy in air or in the presence of a suitable oxidant;    c. combining the oxidized alloy with macroparticles of a metal oxide;    d. thermally coalescing said internally oxidized alloy and said metal oxide into dispersion strengthened composite stock.    
     
     
         7 . Electrical contacts made by using the composition of claim  1 .