In-situ  observation and measurement of graphene layer cross-linking induced  tribological behavior of nanocrystalline carbon films

Grant Number：51305332

Aiming at the scientific problem of “Principle of nano-scale  tribological behavior for nanocrystalline carbon films induced by graphene sheets cross-linking”, in-situ transmission electronic microscopy (TEM) observation and measurement on the nano-scale contact, friction and wear of nanocrystalline carbon film (NCF) against diamond tip are performed. The NCF consists of graphene sheets cross-linkings with different sizes. Nanoindentation tests are carried out in the TEM to measure the critical loads for displacement pop-in of NCFs with different graphene sheets cross-linking sizes. By in-situ observing the degree of cross-linking break down when displacement pop-in happens, the trigger of displacement pop-in of NCF by cross-linking breaking down is clarified. Sliding friction with a normal load is conducted in the TEM to evaluate the friction force-sliding distance curves of NCFs with different graphene sheets cross-linking sizes. The break down and regeneration of cross-linking during friction are in-situ observed to elucidate the accommodation effect of cross-linking structural transition on the frictional shear. Reciprocating wear with a normal load is performed in the TEM to test the critical sliding cycle for the generation of wear of NCFs with different graphene sheets cross-linking sizes. The differences of wear mode and cross-linking status are in-situ observed to reveal the mechanism of cross-linking status difference effect on the wear mode. The achievement of this project will build up the nano-scale tribological behavior system of nanocrystalline carbon films induced by graphene sheets cross-linking, providing research basis for realizing the tribological behavior control of nanocrystalline carbon films in nano-scale.