Effective particle dispersion via high-shear mixing of the electrolyte for electroplating a nickel-molybdenum disulphide composite

The hydrophobic nature of molybdenum disulphide (MoS2) particles is a major challenge for electrodepositing uniform Ni- MoS2 composite coatings due to particle agglomerates present in the aqueous nickel plating bath. In this study, high-shear mixing was shown for the first time as a facile and effective way to achieve a narrow particle-size distribution and stable particle dispersions in the electrolyte, which were characterised by measuring particle-size distributions via dynamic light scattering. The influence of shear mixing duration and speed on particle dispersion in the electrolyte was investigated. The resulting Ni-MoS2 composite coating had a compact structure, showing a lower coefficient of friction and enhanced wear resistance in unlubricated wear tests. In comparison, magnetic stirring was less effective in breaking down particle agglomerates in the bath, which led to a porous and fragile deposit with poor tribological properties.