Studies show that two dimensional(2D)nanomaterial and its hybrid have a great promise in tribology for the special laminar microstructure.However,the majority of performed investigations about 2D graphitic carbon nitride(g-C_(3)N_(4))nanosheets are most focused on energy storage,catalysis,adsorption,rarely tribology.In the present study,g-C_(3)N_(4) supporting mono-dispersed Ag nanoparticle hybrid(g-C_(3)N_(4)/Ag)is prepared,and its microstructure and chemical composition are determined.More specifically,the tribological performance as the lubricating additive of poly phthalazinone ether sulfone ketone(PPESK)composite is investigated using the ball-on-disc friction tester.Moreover,the corresponding enhancement mechanism is well proposed based on the experimental analysis and theoretical simulation.Obtained results show that Ag nanoparticles with a size of about 10-20 nm are homogeneously anchored on g-C_(3)N_(4) nanosheets,favoring for good compatibility between g-C_(3)N_(4)/Ag and PPESK.It is found that when 0.3 wt%of g-C_(3)N_(4)/Ag is added to PPESK,the friction coefficient and wear rate of PPESK decrease by 68.9%and 97.1%,respectively.These reductions are mainly attributed to the synergistic self-lubricating effect of Ag nanoparticles and g-C_(3)N_(4) nanosheet,the formation of transfer film,as well as the limited effect of g-C_(3)N_(4)/Ag on the shear deformation of PPESK composite film.Furthermore,it is found that the proposed g-C_(3)N_(4)/Ag-PPESK composite still keeps reasonable friction-reducing and wear-resistant properties under heavy loads and high rotating speeds.The present study demonstrates that the proposed g-C_(3)N_(4)/Ag hybrid is an excellent lubricating additive for polymer composites.
