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Corrosion Properties of Heterostructured [8YSZ/Al<inf>2</inf>O<inf>3</inf>]N Coatings as a Function of the Bilayer Number

Abstract:

This study presents a detailed analysis of the wear presented in [8YSZ/α-Al2O3] multilayer coatings as a function of the bilayer number when exposed to a corro-erosive environment. In this study, the roughness and grain size decreased by 58 and 30%, respectively when comparing the 70 bilayers system with the 1 bilayer system. The surface factors and the higher bilayer number of the n = 70 system, influenced the 67.33% decrease in corrosion rate compared to the 1 bilayer system. Subsequently, by means of SEM and optical microscopy, the degradation of the coatings due to the impact of abrasive particles and the generation of oxides on the substrate surface caused by a partial delamination of the coating was evidenced. This wear was calculated by means of the mass loss after the corro-erosive test, obtaining a decrease of 55.25% for the system with 70 bilayers with respect to the system with 1 bilayer. The results obtained showed that the system with 70 bilayers presented the best set of electrochemical properties and lower wear in corrosive environments, which makes it the best candidate to be used as a protective coating.