Direct observation by in situ transmission electron microscopy of the behaviour of IF-MoS sub(2) nanoparticles during sliding tests: influence of the crystal structure

Direct observation of the behaviour of individual inorganic fullerenes (IF)-MoS sub(2) nanoparticles in a sliding interface is essential for the understanding of the influence of the intrinsic characteristics of the nanoparticles on their lubrication mechanisms, when they are used as additives in lubricant oil. In this work, in situ transmission electron microscopy sliding tests were performed on two different types of MoS sub(2) nanoparticles synthesised by two different methods. It is shown that the IF-MoS sub(2) nanoparticles having perfect structure with a high crystalline order and without defects are able to roll and to slide under the combined effect of pressure and shear stress, whereas the IF-MoS sub(2) nanoparticles containing many defects exfoliate immediately in the same conditions to deliver MoS sub(2) layers covering the mating surfaces. A link between these results, the lubrication mechanisms of the nanoparticles and their tribological properties at the macro-scale was established, proving that the lubrication mechanisms of fullerenes depend on their intrinsic characteristics. Copyright copyright 2013 John Wiley & Sons, Ltd.