Improving tribological properties of (Zn–Ni)/nano Al2O3 composite coatings produced by ultrasonic assisted pulse plating

• SEM indicated on the elimination of cracks and pores when ultrasounds were used.
• XRD result showed nano sized grains of Zn–Ni matrix was developed in this research.
• Simultaneous pulse plating and ultrasonic conditions improved the properties of the coating.
• A (Zn–Ni)/nano alumina uniform composite coating for especial applications was developed.
• Micro hardness and wear behavior of the coating was modified by intensifying the ultrasound.

In this study pulse electroplating was used to deposit the composite coating of (Zn–Ni) strengthened by Al2O3 nanoparticles on mild steel plate. The effect of Al2O3 fraction and ultrasonic irradiation on the properties of the composite coating was also investigated. Scanning electron microscopy and energy dispersive spectroscopy techniques were employed to characterize the morphology and composition of the coating. Topography and surface roughness were investigated by atomic force microscopy. Also in order to evaluate the mechanical properties of the coating micro hardness and wear tests were conducted. It was found that coating hardness was increased from 538 HV to 750 HV and friction coefficient was decreased from 0.588 to 0.392. Results revealed that tribological properties of coating could be improved significantly by using suitable ultrasonic intensity simultaneously with pulse plating.