Improving the corrosion and wear resistance of CoCrNiSi0.3 Medium-Entropy Alloy by magnetron sputtered (CrN/Cr)x multilayer films

In this study, a medium entropy alloy (MEA) system consisting of Co, Cr, and Ni was selected to incorporate Si, resulting in the creation of CoCrNiSi0.3 MEA. The surface was coated with (CrN/Cr)x multilayer films to improve wear and corrosion resistance. The hardness, wear, corrosion, and nanoindentation tests were used to analyze the characteristics of CrN/Cr multilayer films and their protective performance. Low grazing angle X-ray diffraction (GIXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), water contact angle analyzer, and transmission electron microscopy (TEM) were utilized to investigate the composition and structure of (CrN/Cr)x multilayer films. The intermediate Cr layer inhibits the columnar growth of the CrN layers and is progressively refined as the number of CrN/Cr bilayers increases. The Cr layer exhibits superior toughness in the multilayer structure and effectively hinders crack propagation. Therefore, the (CrN/Cr)3 multilayer film has the most outstanding anti-wear performance. The wear rates under 2 N and 4 N loads are 3.331 × 10−6 mm3•m−1•N−1 and 1.124 × 10−5 mm3•m−1•N−1, respectively. The growth of columnar crystals is suppressed and a more compact multilayer film is formed, resulting in a reduction in the defect density and an increase in the water contact angle, which retards the ingress of corrosive liquid and improves corrosion resistance. The corrosion current density of the (CrN/Cr)3 multilayer film is 0.73 μA•cm−2, while the corrosion polarization impedance is 962.35 Ω•cm2.