Characteristics and corrosion behavior of as-deposited and heat-treated Co–Cr/ZrO2 coatings electrodeposited from Cr(III) baths

• Published in: Materials chemistry and physics Vol. 272; p. 125030
• Main Authors: Mahmoudi, E., Mohitfar, S.H., Mahdavi, S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.11.2021; Elsevier BV
• Subjects: Coated electrodes; Cobalt; Corrosion; Corrosion resistance; Cracks; Electrodeposition; Hardness; Heat treatment; Microcracks; Morphology; Nanocomposite; Nanoparticles; Optical microscopes; Protective coatings; Trivalent chromium; Zirconium dioxide; Electrodeposition; Heat treatment; Nanocomposite; Corrosion; Trivalent chromium
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2021.125030

Co–Cr and Co–Cr/ZrO2 coatings were electrodeposited from Cr (III) based baths. The effect of ZrO2 nanoparticles and heat treatment on structure, morphology, cross-section, hardness, and corrosion behavior of the coatings were investigated. The as-deposited Co–Cr coating had an amorphous structure and a nodular morphology that were not changed by the co-deposition of ZrO2 nanoparticles. However, the incorporation of ZrO2 particles decreased the density of micro-cracks within the coatings. According to the optical microscope observations, the micro-cracks were gradually formed within the electrodeposited coatings. The immediate heat treatment after the electrodeposition prevented the formation of micro-cracks and significantly decreased their amount. The results revealed that the composite coatings had a higher hardness and corrosion resistance than the unreinforced Co–Cr coating. The hardness and corrosion resistance of Co–Cr/5 g L−1 ZrO2 coating, as the optimum sample, were 1.2 and 7 times higher than those of the unreinforced electrodeposit. The heat treatment increased the hardness and the polarization resistance of Co–Cr/5 g L−1 ZrO2 coating by 1.5 and 3 times, respectively. •Co–Cr/ZrO2 coatings were successfully electrodeposited from Cr(III) based baths.•ZrO2 nanoparticles decrease the amount of surface defects of Co–Cr films.•Effect of ZrO2 nano-particles on hardness and corrosion of Co–Cr is significant.•Cracks are gradually formed on surface of Co–Cr coatings after electrodeposition.•Heat treatment notably increases the hardness and corrosion resistance of coatings.