Tribological performance of nanocomposite materials

Graphene nanopowder was stirred and dispersed into epoxy resins to form graphene-epoxy nanocomposites by sonication and curing. Surface topography was performed on the as-prepared epoxy, 1wt% and 2wt% graphene-epoxy nanocomposite samples before using sessile liquid drop test, microindentation test, thermal stability analysis and tribological test such as the single way pin-on-disk method to investigate their surface characteristics, tribological, mechanical and thermal properties. Surface profilometry was then conducted on the worn nanocomposites samples and counter balls. The counter ball was part of a hemispherical pin and held tightly in a cylindrical holder based on the pin-on-disk method. This counter ball was replaceable with any ball of 6 mm in diameter and the counter balls used in this project were poly methyl methacrylate (PMMA) balls, aluminum oxide (Al2O3) balls and chromium steel (Cr6) balls. Steady state and running-in coefficient of friction was investigated using the pin-on-disk method for the various nanocomposite-ball pairs. The addition of graphene into the composites had some noticeable effects on the steady state and running-in coefficient of friction depending on the nanocomposite-ball pair types. It was found that the wettability, the surface roughness and thermal stability of the samples did not vary significantly with the successive addition of graphene in the nanocomposite. The decrease in hardness of the nanocomposites contradicted with the decrease in wear depth as the amount of graphene added to the nanocomposites increased. The main reason for this contradiction might be due to the random and unpredictable dispersion of graphene in the nanocomposites. After performing tribological tests, the debris from the shearing of the asperity contacts were transferred between mating surfaces and the overlapping of fragments could be observed on the worn tracks.Bachelor of Engineering (Mechanical Engineering