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Corrosion Behavior of Multilayer PVD Coatings on Inconel Alloy 718

Thursday, 4 October 2018: 10:20
Universal 1 (Expo Center)
F. Almeraya (universidad Autónoma de Nuevo León), C. G. Tiburcio (Universidad Autónoma de Nuevo León), D. Perez Ortiz (Universidad Autonoma de Nuevo Leon), J. A. Cabral, P. Zambrano (Universidad Autónoma de Nuevo León), and M. Montoya (Universidad Autonoma de Nuevo Leon)
The multilayer PVD coatings are used in the aeronautics industry due to high resistance of pitting and crevice corrosion. In this study, the corrosion behavior of multilayers AlCrN/TiSi (85/15), AlCrN/Ti + CrSi and AlCrN/AlCr (70/30) + Cr coatings deposited by Physical Vapor Deposition (PVD) technique were studied. The first layer was deposited from high purity targets of Al and Cr in an N atmosphere at a temperature of 450 °C on 100x100x5 mm plates of Inconel 718 substrate. The second layer was deposited at different temperatures in an inert atmosphere. The multilayer PVD coatings were evaluated by Scanning Electron Microscope (SEM) and potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) measurements were performed in NaCl and H2SO4 solutions. The SEM results showed an adequate distribution of the coatings on the substrate. For the anodic region of the potentiodynamic polarization curves showed that Inconel 718 alloy and PVD coating exhibited a tendency to pseudopasivation behavior in the different corrosive environments. It is observed that some curves have positive hysteresis could be interpreted as susceptibility to pitting corrosion and the Nyquist diagrams two semicircles corresponding to the coatings and the substrate are observed. In general, multilayer PVD coating have a higher corrosion rate in H2SO4, and both multilayers PVD AlCrN/TiSi (85/15) and AlCrN/AlCr (70/30) + Cr coating present pitting corrosion in NaCl and H2SO4, respectively.