Abstract
Nitrided coatings have been used to increase hardness and to improve the wear and corrosion resistance of structural materials. In this work, TiAlN and AlCrN coatings were deposited on Superfer 800H (INCOLOY 800 H) substrate by using Balzer’s rapid coating system (RCS) machine (make Oerlikon Balzers, Swiss) under a reactive nitrogen atmosphere. The coated samples were subjected to optical microscopy (OM), XRD analysis, Field emission scanning electron microscope (FESEM with EDAX attachment), AFM analysis. The corrosion resistance of the substrate, TiAlN-coated and AlCrN-coated samples in a 3 wt% NaCl solution was evaluated and compared by electrochemical potentiodynamic polarization method. It was found that the AlCrN-coating exhibited better corrosion resistance.
Highlights
Superalloys are extensively used in turbine blades of industrial gas turbines and jet engines [1]
aluminum chromium nitride (AlCrN) and titanium aluminum nitride (TiAlN) coatings were deposited on superfer 800H (INCOLOY 800 H) substrate, with a thickness around 4μm
The primary reason was that linear polarization scans were conducted in very small potential range (20mV to + 20mV vs Open Circuit Potential), which does not damage the surface of the sample, unlike Tafel scans, which require scanning over a longer potential range [9]
Summary
Superalloys are extensively used in turbine blades of industrial gas turbines and jet engines [1]. When the superalloys were employed in jet engines, the resistance to pitting corrosion was. Besides the oxidation resistance of superalloys at high temperature, the resistance to pitting corrosion at normal temperature is another important performance of these materials. Chloride ions serve as the catalyzer in accelerating the corrosion process. Plasma assisted physical vapour deposition processes (PAPVD) allow the deposition of metals, alloys, ceramic and polymer thin films onto a wide range of substrate materials. Corrosion performance of nanostructured materials/coatings is a hot topic in corrosion field. The corrosion behavior of the as deposited coatings and substrate in a 3%wt NaCl solution was tested and compared by an electrochemical method i.e. linear polarization resistance (LPR) and potentiodynamic polarization tests. The emphasis is put on the influence of nanostructured coatings on the corrosion behavior of Fe-based superalloy
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