Effect of ultrasonic power on corrosion resistance and hardness of Ni-Co- Al2O3 nanocomposite coatings

The Ni - Co - Al2O3 composite coatings were prepared by electroplating under ultrasound condition. The influence of ultrasonic power on micro hardness and corrosion resistance was investigated. Studied by Scanning Electron Microscope (SEM), Energy Disperse Spectroscopy (EDS) and X - Ray Diffraction (XRD), under the cavitation effect of ultrasound condition, the nano Al2O3 was dispersed in the coating, and the composite coatings had refiner grains. The surface morphology of coating was uniform and compact. With the increasing of ultrasonic power, the micro hardness of Ni - Co - Al2O3 composite coatings increased first and then decreased. When ultrasonic power was 240W, the composite coatings has the highest hardness and the best the corrosion resistance.