A comparative study of the effects of saccharin and β-SiC nano-particles on the properties of Ni and Ni-Co alloy coatings

The effects of saccharin and SiC nano-particles on the properties of Ni and Ni-Co based coatings electrodeposited in modified Watt's baths by sediment co-deposition (SCD) technique were studied. Surface morphologies of Ni and Ni-Co coatings were changed by using saccharin and SiC nano-particles. X-ray diffraction (XRD) results revealed that peak positions and the phase structure of the studied coatings did not change appreciably while the crystallite size and preferred orientation were significantly varied by using SiC nano-particles and particularly saccharin. Although the incorporation of SiC nano-particles had a slight influence on the microhardness of Ni based coatings, using saccharin enhanced their microhardness. However, there was no noticeable difference between the microhardness of Ni-45Co and Ni-45Co/saccharin coatings (containing 45 wt.% Co) while the microhardness of Ni-55Co/SiC nanocomposite coatings (containing 55 wt.% Co) was higher than Ni-45Co and Ni-45Co/saccharin coatings. The potentiodynamic polarization measurements indicated that the corrosion resistance of Ni/saccharin and Ni-45Co/saccharin coatings was better than pure Ni and Ni-45Co coatings. Additionally, the corrosion properties of Ni/SiC and Ni-55Co/SiC nanocomposite coatings were markedly higher than other coatings. Ni-55Co/SiC nanocomposite coatings showed the highest microhardness and corrosion resistance compared to all studied coatings. The unique properties of Ni-55Co/SiC nanocomposite coatings were linked to their alloy matrix and the amount of SiC nano-particles (8.1 vol.%).