In recent years graphene platelets due to their unique structure and remarkable properties have been the focus of interest in studies on practical applications. However, a relatively low number of studies on the tribological applications of graphene platelets have been reported so far. Several researchers have reported that graphite [1] and some graphite derivatives [2, 3] as well as other lubricant materials [4-6] together have the above desirable properties. Zhang et al. [7] investigated the tribological properties of graphene nanosheets. These materials are characterized by weak interatomic interactions between their layers as Van der Waals forces, low-strength shearing [8]. The results indicated that the presence of fullerene was able to increase the load-carrying ability and decrease the friction coefficient and wear. In the present study the tribological behaviour of graphene nanosheets and a more common graphite powder in a mineral base oil were investigated in wide spectrum of contact operating conditions, i.e. from boundary and mixed lubrication to the elastohydrodynamic regimes. Ball on flat setup has been used for tribological characterization. Raman analysis on the steel ball worn surfaces was performed to investigate the presence of graphitic material on the mating surfaces after performing a certain tribological pattern in order to verify the formation of a protective film on the rubbing surfaces due to this additive. Furthermore, the increasing focus toward the loss of mass compensation operated by nanoparticles, has stimulated the investigation about the so-called ‘‘mending effect’’. In fact, the surface mending effect holds a fundamental position in the theory of tribology with nanomaterials; therefore, the involved mechanism has been explored in detail through more specifically designed investigations.
ON THE FRICTION REDUCTION MECHANISM INTRODUCED BY GRAPHENE NANOSHEETS AS ADDITIVE IN OIL LUBRICATED CONTACTS
D'AGOSTINO, Vincenzo;SENATORE, ADOLFO;PETRONE, VINCENZO;CIAMBELLI, Paolo;SARNO, Maria;CIRILLO, CLAUDIA
2013-01-01
Abstract
In recent years graphene platelets due to their unique structure and remarkable properties have been the focus of interest in studies on practical applications. However, a relatively low number of studies on the tribological applications of graphene platelets have been reported so far. Several researchers have reported that graphite [1] and some graphite derivatives [2, 3] as well as other lubricant materials [4-6] together have the above desirable properties. Zhang et al. [7] investigated the tribological properties of graphene nanosheets. These materials are characterized by weak interatomic interactions between their layers as Van der Waals forces, low-strength shearing [8]. The results indicated that the presence of fullerene was able to increase the load-carrying ability and decrease the friction coefficient and wear. In the present study the tribological behaviour of graphene nanosheets and a more common graphite powder in a mineral base oil were investigated in wide spectrum of contact operating conditions, i.e. from boundary and mixed lubrication to the elastohydrodynamic regimes. Ball on flat setup has been used for tribological characterization. Raman analysis on the steel ball worn surfaces was performed to investigate the presence of graphitic material on the mating surfaces after performing a certain tribological pattern in order to verify the formation of a protective film on the rubbing surfaces due to this additive. Furthermore, the increasing focus toward the loss of mass compensation operated by nanoparticles, has stimulated the investigation about the so-called ‘‘mending effect’’. In fact, the surface mending effect holds a fundamental position in the theory of tribology with nanomaterials; therefore, the involved mechanism has been explored in detail through more specifically designed investigations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
