Electrodeposition of Ni-Al2O3 composite coatings employing supercritical CO2 baths

Abstract The co-deposition of Ni and Al 2 O 3 by electrodeposition in supercritical CO 2 (sc-CO 2 ) baths with and without emulsification was studied. The material characteristics of the Ni-Al 2 O 3 composite coatings, including its crystal structure, surface morphology, chemical composition, micro-hardness, wear resistance, and corrosion resistance, were all examined and compared with those of pure deposited Ni. Although a reduction in electrodeposition rate and a lower solid Al 2 O 3 particle content in the composite coatings were obtained incorporating sc-CO 2 bath, substantial increases in the micro-hardness and wear resistance of the coatings were observed comparing with those formed in conventional bath. The advantages of sc-CO 2 electrodeposition, with and without surfactant addition, over the conventional electrodeposition of composite coatings, are addressed.