Revestimento por fricção da liga de alta entropia CoCrFeMnNi: desenvolvimento microestrutural e resistência a corrosão

Abstract

This research addresses the development and characterization of coatings with highentropy alloys (HEAs), with a specific focus on the CoCrFeMnNi alloy, applied to carbon steel and stainless steel substrates by means of the friction surfacing (FS) process in CNC machining centers. The main objective was to improve the FS process in CNC machining centers, aiming at producing CoCrFeMnNi coatings on these substrates. The methodology involved the preparation of alloy samples by arc melting, followed by forging and machining to obtain consumable rods. Friction surfacing was carried out in a CNC machining center, with controlled parameters to ensure coating quality. Microstructural characterization was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD), while penetration resistance was evaluated through Vickers microhardness measurements. The corrosion resistance of the coatings was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 0.5 M H₂SO₄ solution. The results indicated that the CoCrFeMnNi coatings exhibited a homogeneous microstructure with the formation of a face-centered cubic (FCC) phase. Microhardness measurements revealed values lower than those of the as-cast alloy, averaging between 200 and 220 HV. Despite the heterogeneous microstructure reducing the initial corrosion resistance, the CoCrFeMnNi coating exhibited superior passivation in 0.5 M H₂SO₄ compared to 316L steel, suggesting greater potential in passivating environments