Wear Resistance of Electrodeposited Ni–Mn–SiC Composite Coatings

To improve the wear resistance of type 45 steel surfaces, Ni–Mn alloy coatings are prepared through electrodeposition under different sodium citrate concentrations based on which SiC particles of varying concentrations are added to prepare Ni–Mn–SiC composite coatings. The coatings are characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, microhardness testing, surface roughness meter, composite material surface performance testing, and laser scanning confocal microscopy. The results show that adding an appropriate concentration of sodium citrate into the electrolyte can significantly improve the Mn content in the coatings; however, an excessively high concentration increases the residual stress of the coatings and induces cracks on the surface. When the sodium citrate concentration is 40 g/L, the microhardness and wear resistance of the coatings are optimum. The average microhardness of the Ni–Mn alloy coatings is 522.8 HV0.05, and the minimum scratch area of the wear mark is 9526.26 μm2. The addition of SiC particles improves the surface integrity of the composite coatings and further improves the microhardness and wear resistance of the coatings. The composite coating has a maximum average microhardness value of 648.7 HV0.05 for SiC particle concentration of 4 g/L; this value is nearly 25% higher than that of pure Ni–Mn alloy coatings; the minimum scratch area of the wear mark is reduced to 7160.46 μm2.