In this study, FeCrMnWMoSi amorphous/nanocrystalline coating was prepared on stainless steel by high-velocity oxygen fuel (HVOF) spraying. In order to thoroughly evaluate this novel material, the corrosion behaviors and corrosive film characteristics of the amorphous/nanocrystalline coating in NaCl corrosive media were studied using electrochemical measurement technologies such as potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). It was found that the corrosion resistance of Fe-based amorphous/nanocrystalline coating could be attributed to the passive film formed, which consisted of Fe, Cr, Mo, and W oxides. pH has an important influence on the corrosion resistance of amorphous/nanocrystalline coating by changing the pitting corrosion mechanism. Under neutral and acidic conditions, the corrosion mechanism of Fe-based amorphous/nanocrystalline coating was mainly local pitting corrosion. However, under strong alkaline conditions, the amorphous/nanocrystalline coating not only had pitting corrosion, but also had the active dissolution of the passive film. Therefore, the anti-corrosion performance of Fe-based amorphous/nanocrystalline coating under alkaline conditions was not as good as neutral and acidic corrosive medium.

Iridium (Ir) coating was electrodeposited on tungsten (W) substrate for resistance to high-temperature oxidation. The reduction of iridium was studied using an electrochemical cyclic voltammetry (CV) measurement technique. The structure characterization and performance testing were carried out by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a high-temperature oxidation test. The results showed that the reduction of tetravalent iridium ions to metallic iridium included three reduction steps. The deposited iridium coating had a fine polycrystalline + amorphous structure, no grain orientation phenomenon was observed after electrodeposition, and the microstructure was isotropic. The iridium-coated tungsten metal had excellent resistance to high temperatures at 1300 K, which was attributed to the better chemical stability of the oxide film generated on the surface of the iridium coating.