An Ni/nanodiamond composite coating was deposited on carbon steel in a traditional Watt’s solution without additives via direct current (DC) electroplating. The effects of the nanodiamond concentration and current density in the plating solution on the morphology, grain size, and texture of the Ni/nanodiamond composite coating were observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The distribution of the nanodiamond particles in the composite coating was investigated by Raman spectra and SEM. The mechanical properties of the composite coating, such as its elastic modulus and hardness, were examined using a Nano Indenter XP nanometer mechanical test system. The coefficient of friction was tested using a Universal Micro-Tribotester. The results demonstrated that the preferential orientation of the Ni/nanodiamond composite coating varied from the (111) crystal orientation of the pure nickel coating to the (200) crystal orientation. When the nanodiamond concentration in the plating solution was 8.0 g/L and the current density was 3.0 A/dm², the hardness of the composite coating reached the maximum value of 5.302 GPa and the friction factor was maintained at around 0.1. The average grain size of the composite coating was reduced to 20.4 nm.

A nickel-nanodiamond composite coating was prepared on the surface of annealed 45 carbon steel by double-pulse electrodeposition. The effect of nanodiamond particle content on the surface morphology, grain size and wear and corrosion resistance of the composite coating were investigated. According to the analysis of the test results of X-ray diffractometry and scanning electron microscopy, it was found that the cathodic polarization of the electrodeposition process was enhanced after the addition of nanodiamond particles to the Watts nickel plating solution. The positively charged nanodiamond particles on the surface facilitate the reduction reaction at the cathode. Nanodiamond particles provide crystalline growth sites for the non-spontaneous nucleation of nickel atoms. As the addition of nanodiamond particles increases, the diffusely distributed nanodiamond particles are able to attract more nickel ions to deposit nuclei, and its fine crystallization effect increases, resulting in improved wear resistance and corrosion resistance of the composite plating. Among the results, the polarization potential was the smallest when the nanodiamond content in the plating solution was 10 g/L. The surface of the prepared nickel-nanodiamond composite coating was relatively flat and smooth, with good density and a uniform grain size distribution, and the content of element C on the surface of the composite coating was the largest, reaching 1.99%.

In this study, using 45# carbon steel as the substrate, a first experimental analysis was carried out on the polarisation behaviour of different component wattage plating solutions in order to determine the reasonable content of nanodiamond particles in a nickel/nanodiamond composite plating solution. Secondly, the effect of double-pulse forward and reverse duty cycle and reverse working time on the performance of nickel/nanodiamond composite plating was then investigated by testing the thickness, hardness and surface roughness of the composite plating and observing the surface micromorphology. The experimental results show that, when the content of nanodiamond particles in the plating solution is 5 g/L, the anti-pulse working time, forward and reverse pulse duty cycle of the double-pulse plating parameters are 20 ms, 0.3 and 0.2, respectively, and the composite plating layer prepared by double pulse has good comprehensive performance. This research work provides technical support for the optimisation of process parameters for the preparation of nickel/nanodiamond composite coatings by double-pulse electrodeposition.

The amount of wear is one of the most important indicators for assessing the wear resistance of materials, controlling product quality and studying the mechanisms of frictional wear of materials. Due to the limitations of the friction and wear test equipment currently in use for measuring material wear resistance, it is not possible to accurately compare the wear resistance of two different materials. To solve this problem, this paper proposes a new type of friction and wear tester. With the newly designed friction and wear tester, it is possible to perform friction tests and in situ measurements of wear on two different materials at the same time. This will significantly reduce the measurement errors of currently used friction and wear test equipment that requires adjustment in order to measure the amount of wear; it is particularly suitable for accurately comparing the wear resistance of two different materials. The newly designed friction and wear tester can be used extensively to test and analyse the wear resistance of solid materials such as metals, ceramic materials and engineering plastics.