Study of the electroplating mechanism and physicochemical proprieties of deposited Ni-W-Silicate composite alloy

In this work, layers based on Nickel-Tungsten (Ni-W) were electroplated from citrate-ammonia bath with and without silicate addition. Firstly, Electrochemical Quartz Crystal Microbalance (EQCM) and Global Discharge Optical Emission Spectroscopy (GDOES) were used to investigate the electroplating mechanism of both coatings. The gain mass was 14 and 4.13 mu g cmaZ(-2) for Ni-W-SiI and Ni-W coatings, respectively Secondly, the morphology of the composite alloy shows a smooth and homogenous surface with compact cauliflower like-structure identified as silicate incorporation. Finally, after a long immersion into chloride solution, Ni-W-SiI composite film showed a good surface stability and a remarkable mechanical hardness. These proprieties enhanced the electrochemical behavior of the composite alloy. (C) 2013 Elsevier Ltd. All rights reserved.