Surface characterization of the Zn–Ni–Al 2O 3 nanocomposite coating fabricated under ultrasound condition

Abstract

Zn–Ni–Al 2O 3 nanocomposite coating, which was fabricated by eletrodeposition technique with the aid of ultrasound, was investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). The results reveal that 7.2 wt.% nano-alumina particles uniformly dispersed in the matrix of the composite coating. The XPS analyses demonstrate that the outermost layer of Zn–Ni–Al 2O 3 coating was composed of nano-alumina and Zn(OH) 2, while the transition layer between the outermost layer and the Zn–Ni matrix consisted of nano-alumina, metallic Zn, ZnO and metallic Ni. In order to investigate the influences of ultrasonic agitation and the incorporation of nano-alumina on the composition and surface structure of Zn–Ni matrix, the comparison studies of Zn–Ni–Al 2O 3 nanocomposite coating with Zn–Ni coatings fabricated with and without ultrasound were conducted. The results indicate that ultrasonic agitation resulted in a decrease of Ni content in the Zn–Ni matrix and an increase of the thickness of surface oxide layer; while the incorporation of nano-α-Al 2O 3 increased the Ni content in the Zn–Ni matrix.