High-frequency pulse electrodeposition and characterization of Ni–Co/ZrO2 nanocomposite coatings

Abstract

Ni–Co/ZrO2 nanocomposite coatings were produced by high-frequency pulse electrodeposition in a modified Watt’s bath containing ZrO2 particles. The surface morphology, microstructure, and high temperature oxidation resistance of the coatings were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, and isothermal oxidation tests. It was found that the presence of ZrO2 particles resulted in changes in the morphology and structure of the coatings. The results also confirmed the nanostructure and uniform distribution of ZrO2 particles of Ni–Co/ZrO2 nanocomposite coatings. The addition of ZrO2 did not change the preferred orientation (200), but remarkably affected the relative intensity of planes of Ni–Co alloy. The influence of duty cycle, average current density, and frequency on the amount of incorporated ZrO2 particles in the Ni–Co/ZrO2 nanocomposite has been also investigated. The Ni–Co/ZrO2 nanocomposite coatings with highest ZrO2 content (11.6 wt%) were prepared under the condition of duty cycle of 40 %, average current density of 5 A dm−2, and frequency of 100 kHz. Moreover, the embedded ZrO2 particles significantly improved the high temperature oxidation resistance of Ni–Co alloy coatings. The oxidation rate of Ni–Co/ZrO2 nanocomposite coatings decreased with increasing the ZrO2 content of the coatings.