Structure and properties of super-hard (MoSiTiVZr)N high-entropy nitride coatings regulated by substrate bias

MoSiTiVZr high-entropy alloy coating is rich in strong nitride forming elements, and its nitride coatings have been proved to have super-high hardness, excellent wear resistance, and corrosion resistance. The energy of sputtered particles shows significant influence on properties of (MoSiTiVZr)N high-entropy nitride coatings. In this work, substrate bias of different power is applied to the sputtering deposition process of (MoSiTiVZr)N high-entropy nitride coatings to obtain deposited ions of different energies. The microstructure, hardness, fracture toughness, adhesive force, friction and corrosion resistance of the coating were investigated. The growth mode of the coating changes from columnar to granular with a raised substrate bias power (P_b). All coatings exhibit a crystal structure similar to NaCl-type face-centered cubic (FCC). The hardness changes like a parabola with the increase of the P_b, reaching a super-hard value of 48.4 GPa, which is 2.6 times that of the coating without the bias, while the fracture toughness decreases. The hardness and toughness have a combined effect to the coating adhesive force and wear resistance. The regulation mechanism of substrate bias to hardness, fracture toughness， wear resistance, adhesive force, and corrosion resistance of the coating is discussed in detail. In this study, (MoSiTiVZr)N high-entropy nitride coating synthesized with P_b of 50 W has the best comprehensive properties and is suitable for use as a protective coating.