Metal composite powder and method for producing same

Abstract

There is prepared a silver-coated copper powder wherein the surface of a copper powder having an average particle diameter of 0.1 to 100 μm is coated with 5% by weight or more of silver, and the silver-coated copper powder is sprayed into the tail flame region of a thermal plasma to cause silver on the surface of the copper powder to diffuse in the grain boundaries of copper on the inside of the copper powder to produce a metal composite powder wherein the percentage of the area occupied by silver on a cross section of the metal composite powder is 3 to 20%.

What is claimed is: 
     
         1 . A method for producing a metal composite powder, the method comprising the steps of:
 preparing a silver-coated copper powder wherein the surface of a copper powder is coated with silver; and   spraying the silver-coated copper powder into a tail flame region of a thermal plasma to cause silver on the surface of the copper powder to diffuse in a grain boundary of copper on the inside of the copper powder.   
     
     
         2 . A method for producing a metal composite powder as set forth in  claim 1 , wherein said tail flame region of the thermal plasma has a temperature of 2000 to 5000 K. 
     
     
         3 . A method for producing a metal composite powder as set forth in  claim 1 , wherein said copper powder is produced by atomizing. 
     
     
         4 . A method for producing a metal composite powder as set forth in  claim 1 , wherein said copper powder has an average particle diameter of 0.1 to 100 μm. 
     
     
         5 . A method for producing a metal composite powder as set forth in  claim 1 , wherein the content of silver with respect to said silver-coated copper powder is not less than 5% by weight. 
     
     
         6 . A metal composite powder comprising:
 a copper powder; and   silver diffusing in a grain boundary of copper on the inside of the copper powder.   
     
     
         7 . A metal composite powder as set forth in  claim 6 , wherein said copper powder has an average particle diameter of 0.1 to 100 μm. 
     
     
         8 . A metal composite powder as set forth in  claim 6 , wherein the content of silver with respect to said metal composite powder is not less than 5% by weight. 
     
     
         9 . A metal composite powder as set forth in  claim 6 , wherein the percentage of an area occupied by silver on a cross section of said metal composite powder is 3 to 20%.