High-entropy Fe–Co–Cr–Ni–(Cu) coatings with enhanced corrosion and tribocorrosion resistance obtained by vacuum electrospark deposition

High-entropy coatings are highly promising for protecting steel parts in coastal and marine infrastructure from corrosion and tribocorrosion. This study examines the properties of medium- and high-entropy Fe–Co–Cr–Ni–(Cu) coatings produced by vacuum electrospark deposition. The coatings, with thicknesses of up to 30 μm and varying copper content, exhibit a single-phase solid solution structure with an FCC lattice and a dense, homogeneous morphology. The addition of 14 at.% Cu was found to enhance corrosion resistance, shifting the corrosion potential to 100 mV. In friction conditions within artificial seawater, the inclusion of copper also improved tribocorrosion properties, raising the corrosion potential during friction to –165 mV. This improvement is attributed to the galvanic deposition of dissolved copper on the worn areas of the coating, which also reduces the friction coefficient from 0.37 to 0.26. The Fe–Co–Cr–Ni–(Cu) coatings demonstrate high wear resistance, ranging from 5.6 to 9.6·10^–6 mm³/(N·m). The findings confirm the potential of these coatings for applications in environments subject to both friction and corrosion.