Influence of Laser Remelting on the Corrosion Resistance of Fe-Based Amorphous Composite Coatings

The microstructure and corrosion resistance of Fe-based amorphous coatings prepared by laser remelting after arc spraying were studied. The laser remelting process was carried out under different energy inputs, and the processing parameters varied with the different currents, pulse widths and scanning speeds. The corrosion behavior of the coatings in 1 mol/L NaCl solution was studied through potentiodynamic and potentiostatic polarization test. The morphology and microstructure of the coatings were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical analyzer. A Vickers hardness tester was also used to measure the microhardness of the coatings. The analysis of the microstructure shows that the amorphous coatings are composed of amorphous matrix and nanocrystalline phases. The diffusion of elements indicates a metallurgical bonding between the coating and substrate. The electrochemical corrosion results obtained from the Tafel polarization curves verify that the amorphous composite coatings prepared by different methods show no significant differences in their corrosion resistance, while the microhardness of laser remelting coatings increase obviously with the increase of laser currents. The corrosion resistance of laser remelting coatings is improved extensively due to the amorphous matrix and embedded nanocrystals, which popularizes the applications of amorphous coatings to a large extent.