Deposition, characterization and electrochemical evaluation of Ni-P-nano diamond composite coatings

Simultaneous electroless deposition of particles between layers of Ni-P depositions can improve their properties, especially general corrosion and erosion-corrosion behavior by means of nano diamond as reinforcing particles. In this study Ni-P/nano-diamond composite deposition were coated on steel substrate. Structure of the coatings and corrosion resistance of them were investigated by scanning electron microscopy (SEM) and electrochemical evaluations in salty media. The nano-sized structure of the composite depositions was obtained without using any surfactants. The results demonstrated higher corrosion resistance and greater hardness as compared to the deposited Ni-P. The optimum concentration of diamond nano-particles was found by study of hardness measurement, linear polarization and electrochemical impedance spectroscopy (EIS).

► Diamond nanometer particles have been co-deposited to Ni-P matrix successfully by electroless process. ► The composite structure of the deposition was evaluated as nano size without using any surfactants. ► Incorporation of diamond nanometer particles significantly increase the hardness of depositions as compared to the Ni-P as deposited matrix. ► Corrosion behavior improves by embedding nano-diamond particles within Ni-P matrix due to decreasing porosity density by the accommodation of nano particles to them. ► It was revealed that 1 g/L concentration of diamond nanometer particles provides the optimum deposition condition for Ni-P/nano-diamond coating.