Corrosion characteristic of pulsed electrodeposition Ni–Co/SiC nanocomposite coating

Abstract

Microstructures, Surface morphology and composition of nanocrystalline Ni–Co alloy coating and Ni–Co/SiC nanocomposite coating synthesised by pulse electrodeposition have been studied by XRD, SEM and EDS. The corrosion characteristics of nanocrystalline Ni–Co alloy coating and Ni–Co/SiC nanocomposite coating were comparatively investigated by immersion corrosion test and electrochemical polarisation method respectively. The experimental results indicate that nanocrystalline Ni–Co alloy coatings and Ni–Co/SiC nanocomposite coatings can be synthesised by pulse electrodeposition. With introducing and increasing nano‐SiC particles, the grain size of Ni–Co/SiC nanocomposite is being decreased while the microhardness is increasing. The Ni–Co/SiC nanocomposite coating exhibited better corrosion resistance in 3·5 wt‐% NaCl solution and 5 wt‐% HCl solution than nanocrystalline Ni–Co alloy. The surface morphology of all samples after corrosion in 3·5 wt‐% NaCl solution show evidences of little corrosion. However, samples corroded in 5 wt‐% HCl solution show uniform corrosion.

Keywords:

• Pulse electrodeposition
• Ni–Co alloy coating
• Nanocomposite coating
• Corrosion resistance

This work was supported by The Natural Science Foundation of Fujian Province (grant no. E0810006). The authors thank Mrs Q. Q. Zhou and Mr Q. M. Huang for their help in the SEM, EDS, and XRD measurements.