The effect of co-electrodeposited ZrO2 particles on the microstructure and corrosion resistance of Ni coatings

Abstract

Pure Ni and Ni–ZrO2 composite coatings were electroplated using a Watt’s bath containing different amounts of ZrO2 to be co-deposited. Surface morphology and microstructure of the samples and particle distribution in the coatings were studied using optical microscope, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The results showed that the electroplated sample in the bath containing 90 g l−1 ZrO2 has the maximum particle content and the best particle distribution. Evaluation of microstructure and corrosion behavior demonstrated that with increasing ZrO2 content in the coating, the corrosion potential shifted toward noble and positive values. This is probably due to diminishing of the metallic surface area exposed to the solution. Higher ZrO2 contents in the coating results in lower corrosion current densities probably due to the changing of the microstructure from coarse-grained columnar to fine-grained granular structure. The results revealed that the electroplated sample in the bath containing 90 g l−1 ZrO2 has the best corrosion resistance.