Preparation of Flake Silver Coated over Copper Powder

Abstract

Flake copper powder is coated with silver by using a solution containing [Ag (NH3)]+. Factors such as copper particle size distribution, [Ag (NH3)]+ concentrations and the dispersing agent are studied and correlated with the silver content of coated copper and electric conductivity. At the condition of silver concentration of 0.8 mol/L and dispersing agent of 1.0g/L a powder of copper coated with silver with electric conductivity of 0.8×10-3Ω·cm is obtained. XRD patterns indicate that the powder consists of only the Cu and Ag phases without other intermediate phases. SEM results with different silver contents reveal that when Ag content rises, its surface topography transforms through the steps: individual particles → small islands → continuous 2D layers → multi-layers.