51316-7443-Corrosion Behavior in Saline Solution of Pulsed Electrodeposited Nanocomposite Zn-Ni/CeO2 Coatings

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Product Number: 51316-7443-SG

ISBN: 7443 2016 CP

Author: Juan CREUS

Publication Date: 2016

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coatings combining mechanical and tribological properties with improved corrosion resistance are strongly developed since recent years. Among potential alternatives metal matrix composite coatings give rise to special interests. Indeed incorporation of ceramic nanoparticles may allow to increase mechanical properties of the metal matrix but the influence on this further phase on the surface reactivity remains controversial.We studied the influence of the incorporation of nanoparticles of ceria on morphological and microstructural characteristics of a Zn- 15wt. % Ni coating. Coatings were synthesized by electrodeposition from a conventional chloride acidic bath without commercial additives. Coatings were deposited at 25°C by direct and pulse (simple and reverse) plating modes. Electrodeposited Zn-Ni coatings are characterized by a g-Zn-Ni single phase that was reported as the most corrosion resistant phase in saline solution [1-3].Incorporation of ceria nanoparticles does not drastically change the morphology of Zn-Ni deposits contrary to observations carried out on pure Zn matrix nanocomposite coatings [4]. In the study of Exbrayat & al [45} it was denoted that the typical morphology consisting in superposition of hexagonal platelets characteristic of electrodeposited Zn coatings without additives limited the amount of CeO2 introducted into the matrix. The particles were mainly located at grain boundaries or in defects like pores or voids. Morphology of Zn-Ni alloys seems to be more appropriated for an enrichment of nanoparticles and the use of pulse plating conditions permits to easily control this morphology preserving the single-phased nature of the coating.Corrosion behavior of nanocomposite coatings is discussed in relation to the different metallurgical states and particle amount Moreover atomic absorption spectroscopy is used to follow the release kinetics of metallic ions towards the saline environment. These results will be compared to a model Zn/CeO2 system in order to understand how particles may influence reactivity of the coating.[1] K.R. Baldwin M.J. Robinson C.J.E. Smith. Corros. Sci. 35 (1993) 1267-1272.[2] G. Barceló J. García M. Sarret C. Müller J. Pregonas. J. Appl. Electrochem. 24 (1994) 1249-1255[3] K.R. Sriraman S. Brahimi J.A. Szpunar J.H. Osborne S. Yue. Electrochim. Acta 105 (2013) 314-323.[4] L. Exbrayat P. Steyer C. Rébéré C. Berziou C. Savall P. Ayraut E. Tertre; G.L. Joly Pottuz J. Creus. J. Solid State Electrochem. 18 (2014) 223-233.[5] L. Exbrayat E Calvié T. Douillard G. Marcos C. Savall C. Berziou J. Creus P. Steyer. ECS Electrochem. Lett. 3 (2014) D33-D35.