| 摘要 |
PROBLEM TO BE SOLVED: To obtain particles having a specified compsn. and average particle size and improved in electrical conductivity, corrosion-resistance and migration resistance by composing the particles of a core part essentially consisting of copper and contg. silver and a surface layer essentially consisting of silver, contg. copper and forming a continuous concn. gradient of copper and silver on the side of the core part. SOLUTION: An alkaline earth metal compd., a copper compd. and the powder of a silver raw material are mixed by a ball mill or a beads mill to form a powdery mixture in which the weight ratio of silver to copper is regulated to (1 to 75):(25 to 99). This powder is calcined at 400 to 800 deg.C to form copper and silver into metallic shapes, after that, heating is executed at 700 to 1200 deg.C higher than the roasting temp. to mutually diffuse copper and silver and to enritch the surface layer of the powder particles with silver, and furthermore, an alloy concn. gradient layer in which the content of copper continuously increases from the surface layer to the core part. Next, the alkaline earth metal compd. in the heated material is dissolved away with acid to form into powder with 0.1 to 10μm average particle size contg. 1 to 75 wt.% silver. Preferably, 5 to 40 wt.% Ni is incorporated into the powder.
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