The effect of graphite particle size on the corrosion and wear behaviour of the PEO-EPD coating fabricated on commercially pure zirconium

The practical importance and intricacy in the application of zirconium and its alloys have triggered widespread attention towards the enhancement of its mechanical and corrosion resistance properties. Composite coatings were fabricated on zirconium metal by integrating Plasma electrolytic oxidation (PEO) and Electrophoretic deposition process (EPD). The effect of particle size on the PEO-EPD coating characteristics were studied by comparing the properties of the coatings produced in micro and nano sized graphite particle containing electrolytes. The surface morphology, topography was studied using scanning electron microscope (SEM) and optical profilometer, and the phase analysis was done using X-Ray diffraction (XRD). The diffraction peaks corresponding to graphite indicate the successful incorporation of graphite particles in the coating fabricated in the particles containing electrolyte. The electrochemical corrosion studies by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) reveals the superior corrosion resistance of nano graphite incorporated zirconia coating. The increase in wear resistance and scratch resistance was also observed for the nano graphite incorporated coating. Thus, incorporation of the nano graphite particle into the zirconia layer proved to be beneficial for improving wear, friction resistance, scratch resistance and electrochemical corrosion resistance.