TRIBOLOGICAL BEHAVIOUR AND CORROSION IMPROVEMENT OF THE CHROMIUM COATED PISTON RINGS BY GRAPHENE OXIDE

Corrosion and wear protection of metal surfaces is an important phenomenon in industrial applications in order to prevent material losses from the surfaces. Graphene is a material which synthesized from the graphite or growth via chemical vapor deposition (CVD) as a single layer of carbon atoms with hexagonal lattice structure and sp2 covalent bonding. Graphene oxide (GO) is one form of the graphenebased materials and is highly promising for corrosion inhibition. To date, corrosion protection of this material has been widely investigated as a sheet on copper or nickel surface. However, to the best of our knowledge, anti-wear reduction of this material has not been investigated especially under lubricated condition. In this paper, chromium coated piston ring was coated GO by CVD at ambient pressure furnace. Optical microscope, scanning electron microscope (SEM/EDX), atomic force microscope (AFM) and Raman analysis were used to characterize the GO coatings. Corrosion resistance of the coatings was evaluated by SP-150 potentiostat galvanostat with 0.5 and 1 M sulphuric acid solutions and wear behaviour of the coating was evaluated by tribometer tests under lubricated condition. Results showed that GO significantly reduced the corrosion rate of ring at extreme corrosive media when compared to chromium ring. Furthermore, GO reacted with ZDDP and form tribofilm to provide wear resistance to ring, which resulted in very effective wear protection because of no wear scar observation on the ring surface.