Effects of physically deposited multilayer graphene platelet and graphite on tribological performance of alumina on alumina contact

Multilayer graphene platelet and expanded graphite were deposited on alumina disk surface and their effects on tribological performance of an alumina–alumina contact in different environments were evaluated using a pin-on-disk tribometer. Experimental results indicate that coefficients of friction at the contact are reduced by deposited particles due to their lubricating effect. It is interesting to find that wear of the contact in dry conditions is less than that under liquid lubrication. Tribofilm plays a key role in the wear reduction performance. In liquid media, however, formation of tribofilm is limited due to fluid flow and formed thin tribofilm is not able to protect the contact from wear. Experimental results show that formation of tribofilm is improved by both multilayer graphene platelet and expanded graphite. This is attributed to the higher adhesion force between graphene and alumina than that between alumina and alumina. The findings demonstrate that deposition of graphene-based materials onto alumina surface hold the promise of providing a new pathway to increase the anti-wear performance of alumina and possibly other ceramics