Tribological Evaluation of a UHMWPE Hybrid Nanocomposite Coating Reinforced with Nanoclay and Carbon Nanotubes under Dry Conditions

A novel hybrid polymer nanocomposite coating of ultrahigh molecular weight polyethylene (UHMWPE) reinforced with nanoclay (C15A) and carbon nanotubes (CNTs) has been developed to protect metallic mating surfaces in tribological applications. The hybrid nanocomposite coatings were deposited on aluminum substrates using an electrostatic spraying technique. Ball-on-disk wear tests using a 440C stainless steel ball as the counterface were conducted on the coatings under dry conditions to determine the optimum amount of the loadings of the nanofillers and evaluate their tribological performance at different normal loads and linear velocities. Micro-indentation, raman spectroscopy, scanning electron microscopy (SEM), and optical profilometry techniques were used to characterize the coatings in terms of hardness, dispersion of the nanofillers, morphology, and wear mechanisms, respectively. Results showed that the UHMWPE hybrid nanocomposite coating reinforced with 1.5 wt % of C15A nanoclay and 1.5 wt % of CNTs did not fail even until 100,000 cycles at a normal load of 12 N and a linear speed of 0.1 m/s showing a significant improvement in wear resistance as compared to all other coatings evaluated in this study.