Effects of Process Parameters on the Morphologies and Composition of Pulse Electrodeposition of Nickel-Rich Co-Ni Alloys

Nickel-cobalt alloys have broad application prospect for their excellent properties (i.e. high microhardness, strength, abrasion, corrosion resistance and magnetic properties.etc). Nickel-rich Ni-Co coatings were produced on SUS304 substrates by pulse electrodeposition from sulfamate electrolytes with different average current density, pulse frequency, duty cycle and different bath temperature. It is clearly observed that the content of cobalt in the nickel-rich deposits gradually increases from 4.29 % to 25.47 % as the Co2+/Ni2+ concentration ratio increasing from 0.022 to 0.1(the current density applied was 2 A/dm2,bath temperature 25 °C). The Co content increases from 16.98 % to 25.47 % to 30.06 % when the duty cycle ranged from 20 % to 50 % to 60 %.The Co content seems to hardly change when pulse frequency changed from 500 Hz to 1000 Hz. The cobalt content decreases as the growth of the current density. The formation of good Ni-Co deposits with high cobalt content and smooth morphologies can be obtained by reducing current density, increasing bath temperature and pulse duty cycle.