HIPIMS and PVD coatings under sliding contact: Comparative tribological evaluation of dry friction and boundary lubricants enhanced with graphene and fullerene additives

This study investigates the tribological performance of coatings deposited on steel substrates via HIPIMS (DLC, TiAlSiN, TiAlN and CrN) and PVD (TiN and TiCN) techniques under dry friction and lubricated conditions using commercial oil enhanced with graphene and fullerene additives. Graphene- and fullerene-enhanced oils reduced the interfacial temperature by 65–75% and the friction by approximately 40–60% compared to dry sliding. Among all coatings, DLC and TiAlN showed the lowest friction in both dry friction and oil-lubricated conditions. Both nanoadditive-enhanced lubricants reduced frictional heating to below 50 °C, whereas commercial oil maintained temperatures between 50–65 °C and dry sliding generated severe heating, reaching up to 180 °C for CrN. Wear analysis revealed strong coating–lubricant compatibility effects, with graphene and fullerene additives reduced wear volume by up to 70% relative to commercial lubricants. Overall, the findings provide insights into the synergistic effects of HIPIMS coatings and nanoadditive-enhanced boundary lubricants on wear mechanisms, particularly their influence on the onset of sliding temperature and friction.