Study On Nanofriction Properties Of Two-Dimensional Layered Materials Based On Atomic Force Microscopy

Friction and wear are prevalent in daily life and are one of the major reasons of loss in energy,mechanical fault,inefficiency.Therefore,it is very important to solve the problem of friction and wear.Two-dimensional layered materials have attracted much attention due to their excellent lubrication and anti-wear properties,making them excellent candidates for micro and nano interface lubricants.The in-depth study of the microscopic friction mechanism of two-dimensional materials can better regulate their lubrication performance and reduce friction.So far,most studies have been conducted in dry gas or high vacuum environments,and there is a lack of research on tribological properties in complex systems that are closer to real-world applications.Moreover,there are fewer studies on the influence of material structure on tribological properties.Based on this Status,this thesis relies on atomic force microscopy(AFM)techniques to investigate in depth the nano-frictional properties of four two-dimensional layered materials,2H-TaS2,1T-TaS2,1T-ReS2,and h-BN,as follows:(1)Comparison of nano-friction properties of 2H-TaS2,1T-TaS2 and 1T-ReS2.The results show that the friction law of the three materials is:2H-TaS2>1T-TaS2>1T-ReS2,and the corresponding coefficient of friction(COF)are 0.175,0.125 and 0.115,and the lubrication performance is excellent.By means of Kelvin probe force microscope(KPFM),the mechanisms of lattice configuration and interlayer metal atoms leading to the difference in frictional properties of materials are explained from the perspective of electrostatic force and lattice deformation ability.Our results provide new insights for the regulation of nano friction.(2)Study of nano-frictional behavior of h-BN in liquid environment.In this study,the nano-frictional properties of h-BN in different environment were investigated using AFM.The results show that the layer number dependence of h-BN friction is not affected by the organic solvent environment,and the friction in squalane environment is smaller than that in atmospheric environment,and the lubrication performance is better.By analyzing the adhesion between the tip of the probe and the surface of the sample,it was found that the different test environment would affect the adhesion.In squalane environment,the adhesion was small,so the friction force was small,which realized the explanation of the differences in the friction properties of h-BN in different environments.The results provide guidance for the application of h-BN as solid lubricant and lubricant additive in complex systems.