Microstructural and tribological evaluation of potential self-lubricating coatings with additions produced by the plasma transferred arc technique

Metal matrix composite coatings with potential self-lubricating properties were produced on plain steel substrates using the plasma transferred arc technique (PTA). Layers of approximately 1 mm thickness and with various compositions were obtained with additions of MoS2 and MnS compounds, which are known to act as solid lubricants in a number of applications. Following the microstructural characterization, the tribological behavior of the coatings was investigated using pin-on-disk experiments. Experimental results indicated that the addition of MnS was effective in reducing the friction coefficient and the wear rate of the coatings in comparison to the steel substrate, whereas the MoS2 was ineffective, due to its instability and subsequent redistribution of Mo and S elements during the solidification process.