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.