The Effect of Organic Additives on the Microstructure, Microhardness and Friction Coefficient of Ni/WS 2 Composite Coatings

Composite electroplating enables the production of a wide range of coatings with improved tribological properties. One of the most perspective composite coatings due to its lubricating properties are the Ni/WS2 coatings. The aim of this study was to investigate the effect of organic additives to Watts bath on the microstructure and mechanical properties of Ni/WS2 composite coatings produced by the electrochemical method. The study included the composite coatings deposited in a Watts bath modified by saccharine, polyethylene glycol (PEG), sodium dodecyl sulfate (SDS) and 2-butyne-1,4-diol with disperse phase of WS2 in the form of triturated powder. The particular component was used to obtain a good-quality coating and to enable the proper wettability of tungsten disulfide. The coatings were deposited with direct current. The proper stability of the suspension was ensured by application of the mechanical stirring (400 rpm). The use of the properly selected organic additive in the electrodeposition process results in a significant improvement of the coatings homogeneity, smoothness and the higher microhardness in comparison with composite coatings deposited without additives. The coatings are characterized by increased adhesion to the substrate (low acoustic emission) as well as the lower value of the friction coefficient.