Nickel/MWCNT-Al2O3 electrochemical co-deposition: Structural properties and mechanistic aspects

In this work, composite coatings were fabricated by electrolytic co-deposition of hybrid MWCNT-Al2O3 particles with Ni matrix from a Watts type bath, with and without the use of the sodium dodecyl sulfate additive, under both direct and pulse current conditions. The surface morphology and structural characteristics of the coatings were investigated for the different types of applied current mode, in the absence and presence of the additive. The mechanism of electrochemical co-deposition of Ni and hybrid particles was investigated by linear sweep voltammetry, electrochemical impedance spectroscopy and quartz crystal microbalance measurements in order to elucidate some aspects of the co-deposition mechanism. It was found that the presence of hybrid MWCNT-Al2O3 particles promotes direct proton discharge as well as hydrogen coverage, thus decreasing the deposition efficiency.