Investigation on microhardness and corrosion resistance of ZnO reinforced Ni-P composite coatings at various annealing temperatures

Abstract

ABSTRACT In the process of electroless coatings, mild steel was used as a substrate for the Ni-P-ZnO composite coatings. Present study focused on annealing temperature effect on microhardness and resistance to corrosion of the ZnO reinforced Ni-P coatings. Variation in microhardness and corrosion resistance was observed in Ni-P-ZnO thin film at 200, 400 and 600°C annealing temperatures. Coatings phase transformation behaviour, surface structure and morphological studies were evaluated by X-ray diffraction and scanning electron microscopy (SEM). Chemical composition of the coatings is measured by using Energy dispersive spectroscopy (EDS). Results reveal that annealing temperature significantly affects the properties of the coatings. Increase in annealing temperature from 200 to 400°C improves the microhardness and corrosion resistance of the coatings. At 600°C annealing temperature, formation of coarse structure decreases the properties of the coatings.