Characterization of silver-coated copper particles synthesized by mechanical activation and electroless plating

The effects of mechanical activation on the characteristics of copper and synthesized silver-coated copper powders were investigated. The characterization was carried out using particle size analysis, XRD, BET, SEM, AAS, EDS-map analyses, and electrical resistivity measurements. The obtained results showed that d80 of copper powder changes from 60 to 200 µm as the milling time increases from 0 to 1 h. Meanwhile, by expanding the milling time to more than 2 h, the d80 of the powders decreased to about 50 µm. The specific surface area of copper powder increased from 0.04 to 0.21 m²/g for milling duration of 0.5–1 h. The specific surface area reached to a maximum value of 0.3 m²/g for the milling duration of 16 h. Morphological examination of the core–shell particles produced from 4 to 16 h ball-milled copper powder revealed that surface of the copper particles is completely covered with silver. Studies showed that the apparent density of the samples prepared from Cu–Ag core–shell powder and copper powder decreased from 7.2 to 5.8 g/cm³ and from 6.2 to 5.8 g/cm³, respectively, by increasing the ball milling time from 0 to 16 h. The electrical resistivity of the core–shell bulk samples is always constant (0.25 Ω-cm), but the resistivity of copper bulk samples increased (1–5 Ω-cm) with longer milling time (0–16 h).