Manganese phosphate is an industrial coating material used to reduce friction and improve lubrication in sliding components. In this study, the morphology and tribological properties of uncoated carbon steel and carbon steel coated with only manganese phosphate and with manganese phosphate with nano-MoS2 were investigated. This work shows the effects of nano- MoS2 on the formation of manganese phosphate coatings on steel. The manganese phosphate composite conversion coatings are created by chemical treatment, and the main component of the layer is hureaulite (Mn,Fe)5H2(PO4)4·4H2O. With regard to the effects of nano-MoS2 on the surface of composite coatings, it is obvious that the crystals of coatings formed more compactly with an increase in the nano-MoS2 content from 0 to 5 g/L. The surface microstructure of the coatings formed in a bath with nano-MoS2 was more uniform than that formed in a bath without nano-MoS2. It can be seen that there is a decrease in the size of the domed structure and in the surface roughness as the content of MoS2 increased in the nanocomposite coatings. The effect of MoS2 on the friction and wear behaviors of composite conversion coatings at 3 g can be a very effective deterrent for tribological of decrease.

Keywords: Manganese phosphate coating, Nano-MoS2, Carbon steel, Morphology, Composite chemical treatment