Effects of the carbon-to-nitrogen ratio on the microstructure and properties of (CrNbSiTiZr)CxNy high-entropy carbonitride films

Abstract

High hardness, high toughness, high oxidation resistance, and low friction coefficient are key properties of protective coatings. High-entropy alloy (HEA) films have considerable potential as protective hard coatings for tools used for surface milling, turning, and drilling. However, to date, despite their promise, high-entropy alloy carbonitride films (HEACN) have not been studied extensively. Therefore, in this study, we deposited (CrNbSiTiZr)CxNy on Si(100), SiO2, and WC-Co substrates via radio frequency magnetron sputtering and investigated their microstructures, oxidation behavior, and properties. The (CrNbSiTiZr)CxNy film having a carbon content of 71 at% displayed the lowest friction coefficient (0.13) and wear rate (0.4 × 10−7 mm3/N⋅m). Further, as the nitrogen content was increased, the hardness values, oxidation resistances, friction coefficients, and wear rates of the films also increased, reaching their maximum values at 48.2 at%. X-ray diffraction analysis revealed that all the films exhibited a single face-centered cubic (NaCl-type) structure, and the diffraction peaks shifted to higher angles with increase in the nitrogen content, suggesting an increase in the crystalline nitride phase.