EFFECT OF ELECTROPLATING PARAMETERS ON "HER" CURRENT DENSITY IN Ni-MoS₂ COMPOSITE PLATING

Abstract

Nickel composites with co-deposited insoluble, solid lubricant particles such as MoS2 have been reported to reduce friction. It is known that hydrogen evolution reaction (HER), competes with nickel deposition. The influence of the electroplating parameters and their interaction effects on the peak current density for HER were studied by fractional factorial design. The parameters and their ranges were; MoS2 concentration (0-30 g/l), temperature (30-50 degrees C), pH (2-4) and surfactants (0-1 g/l). Electrodeposition processes were carried out from a typical Watts bath containing leveler, wetting agent and brightener by using a potentiostat. The peak currents (I-p) were extended to higher values and the peaks on linear sweep voltammograms became noticeable by increasing the scan rate from 20 mV/s to 100 mV/s over the range 0 to 2.5 V. The peak current densities (i(p)) for each experimental route were determined by fractional factorial design for three types of mineral processing surfactants; sodiumlignosulfonate (SLS), depramin-C (DC) and ammoniumlignosulfonate (ALS) using Minitab program [1]. Adding MoS2, decreasing temperature and increasing pH has decreasing effect on peak current density for all surfactants. ALS and DC have increasing effect whereas SLS has descending effect on peak current.