Ni-Cr-P composite co-deposition on the surface of 65Mn alloy steel

Abstract

65Mn alloy steel, as a promising raw material for the manufacture of knitting needles, requires in-depth study in order to enhance its surface hardness and wear-corrosion resistance. This study focused on the chemical deposition and properties of Ni-Cr-P composite co-deposition on the surface of 65Mn alloy steel. The effects of plating solution composition, process parameters, and their effects on coating deposition rate, surface hardness, and other indicators were also analyzed. The results showed that, under conditions of 12 g/L CrCl3·6H2O, 5 g/L C6H8O7·H2O, 20 g/L C3H6O3, pH 5.5, and a temperature of 70°C, the coating obtained exhibited optimal performance, with a deposition rate of 3.292 µm/h, a microhardness reaching 627.28 HV0.2, and P and Cr elemental contents of 9.16 and 0.127 wt%, respectively. The coating structure was dense, with good adhesion and minimal porosity. To further enhance the wear resistance, a Ni-Cr-P coating was prepared using the aforementioned process parameters, followed by heat treatment. The effects of heat treatment temperature on the microstructure, microhardness, X-ray diffraction (XRD) spectra, and other characteristics were analyzed. The results indicated an optimal heat treatment temperature for the coating of 200°C. Following heat treatment, the microhardness of the coating remained relatively unchanged, and there was a tendency for the coating structure to become more crystalline, leading to improved wear and corrosion resistance.