Journal of The Electrochemical Society · 2021 · 66 citations · 48 references
Natural SciencesMaterials EngineeringMaterials ScienceCorrosion ScienceMetallic MaterialsSurface ScienceAlloysCorrosion ResistanceCorrosion-resistant MaterialsInorganic MaterialsMetal OxidesX-ray Photoelectron SpectroscopyElectrochemical PassivationNative Oxide FormationNative Oxide LayersNative Oxide PassivationNickel AlloysNickel-based AlloysSecondary Ion Mass SpectrometryTime-of-flight Secondary Ion Mass Spectrometry
X-ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry were combined to characterize the surface oxides (native oxides and passive films) formed on Ni-based alloys containing chromium and molybdenum. Two alloys were studied, Ni-20Cr and Ni-20Cr-10Mo (in wt.%). For Ni-20Cr, both native oxide and passive films formed in acidic medium present a duplex structure comprising a Ni and Cr outer hydroxide layer and a Cr inner oxide layer. The Ni-20Cr-10Mo alloy presents a similar bilayer structure, but with Mo oxide located at the outer layer/inner layer interface. Cr enrichment is observed after passivation for both alloys. The corrosion resistance in acidic solution containing chlorides is enhanced by Mo, and by electrochemical pre-passivation in Cl free solution.
48