Comparison of Corrosion Behavior of ZincBased Nanocomposite Coatings Reinforced With SiC and TiO۲ Particles Fabricated Through Pulse Electroplating Process

In this research, pure zinc, Zn-SiC and Zn-TiO۲ nanocomposite coatings were fabricated through pulse electroplating process from a sulphate bath. While pulse electroplating, the effect of several parameters like maximum current density (ip), frequency and duty cycle were investigated. In order to characterize the obtained coatings, surface morphology of the coatings was investigated by scanning electron microscopy (SEM & FESEM), composition of the coatings by elemental energy dispersive spectroscopy (EDS) analysis,  microstructure by means of X-ray (XRD) method, corrosion measurement by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), surface topography by the use of atomic force microscopy (AFM) and also microhardness of  the coatings were investigated. The highest amount of incorporated SiC nanoparticles was ۸.۷۳ Vol. % and for TiO۲ nanoparticles was ۷.۱۲ Vol. %. Also, minimum corrosion current density for pure zinc coating was ۷.۱, for Zn-SiC nanocomposite coating was ۴.۴۹ and for Zn-TiO۲ nanocomposite coating was ۴.۵۳ µA/cm۲. It was observed that utilization of simultaneous of composite coating system and also pulse electroplating process leads to significant increase in corrosion resistance. XRD analysis also showed that preferred orientation for pure zinc coating is through (۰۰۲) plane. By incorporation of SiC and TiO۲ nanoparticles into the zinc matrix, the intensity for (۰۰۲) plane decreases and (۱۰۱) plane intensity increases. Average roughness for three samples of Zn, Zn-SiC and Zn-TiO۲ coatings was ۵۲۸.۱۱, ۶۲۷.۳۲ and ۸۱۵.۴۱ nm respectively. The microhardness of the coatings was also improved after SiC and TiO۲ incorporation.