Abstract

© 2019 by the authors.The use of solid lubricants such as graphene, graphene oxide, and other nanoparticles have gained notable attention in the tribological community to reduce friction and wear thus aiming at improved energy efficiency and sustainability. Tribological experiments unify rather extreme conditions such as high contact pressures, small contact areas, relative sliding motion, and rapid heating. This combination leads to mechanically- and/or thermally induced chemical, structural and microstructural modifications of the lubricating nanoparticles during rubbing thus altering their material's properties. Due to the high sensitivity, we propose nanocalorimetry as the method of choice to shed more light on the thermally-induced processes and changes. As a model material for solid lubricants, we explore the transitions of graphene oxide under heating with 1000 °C/s up to 600 °C using quasi-adiabatic nanocalorimetry. We identify a strong exothermic runaway reaction at 317 °C. This runaway is preceded by exothermic reactions between 75-125 °C, which are correlated with the release of intercalated species and the formation of CO and CO2.