Enhanced tribological properties of polyimide composite with carbon fiber/graphitic-carbon nitride nanosheets

Developing polymer self-lubricating composites is of great significance for reducing mechanical friction and wear. In this study, a hybrid of graphitic carbon nitride (g-C3N4) nanosheets anchored carbon fiber (CF) was constructed through one-step calcination method to enhance the tribological performance of polyimide (PI). The presence of g-C3N4 improved the interfacial interaction of CF/PI composite by endowing CF surface with active sites and rough microstructure. Tribological test results demonstrated that CF/g-C3N4/PI composite had outstanding antifriction and wear resistance, with friction coefficient and wear rate of 0.209 and 2.23 x 10(-7) mm(3)/Nm, which were reduced by 21% and 73.52% compared to pure PI, respectively. This was mainly attributed to the enhanced interfacial interaction, which was conducive to the stress transferring from PI to CF/g-C3N4 in sliding process. At the same time, the g-C3N4 nanosheets could give the composite excellent self-lubrication property by promoting the formation of transfer film. More importantly, the as-proposed CF/g-C3N4/PI composite still maintained good self-lubricating performance in different sliding environment, with a friction coefficient of 0.132 in water environment and 0.049 in oil environment, suggesting it had a broad prospect in polymer self-lubricating composite. In addition, the corresponding mechanism was discussed based on the analysis of worn surface of the composite and counterpart.