Effect Of Ion Beam Bombardment And Annealing Temperature On Nanotribological Behavior Of Tungsten Disulfide

In the production and application of two-dimensional transition metal chalcogenides,the presence of defects is often difficult to avoid.Therefore,the influence of defects on its surface friction performance has also received widespread attention.In recent years,research on nanoscale friction of two-dimensional materials based on graphene has made great progress.Researchers have found that the friction properties of two-dimensional materials are easily affected by material morphology,chemical structure and molecular defects.Therefore,this paper mainly studies the modification of multilayer and bilayer WS₂ surface by low-energy Ar ion beam bombardment,and then studies the surface friction behavior of WS₂ with defects and the frictional properties of the surface after annealing repair defects.The results of the study are as follows:?1?Without bombardment of bilayer and multilayer WS₂,friction and friction coefficient have a layer-dependent dependence,that is,gradually decrease with the increase of the number of layers;After low energy?30-400eV?Ar⁺bombardment,friction and friction coefficient none of them have the number of layers,showing the same trend,that is,increasing with the increase of bombardment energy?30-70eV?,and finally stabilizing?100-400eV?,the friction coefficient is linear with the bombardment energy.The reason for the increase in friction here may be that when the ion energy is higher than the minimum penetration energy,the S atom is first excited out,and a small amount of S atom vacancies are generated on the surface to increase the friction;as the energy further increases,The atomic vacancies gradually expand,and the surface introduces more defects,so the friction gradually increases;?2?After the bombardment,the bilayer and multilayer surfaces have different degrees of damage.With the increase of energy,there are more and more defects on the surface,resulting in the friction increasing gradually and the energy value of the double layer?70eV?is more than that of the multilayer.The height?100eV?is due to the thinner the number of layers,the weaker van der Waals force,the easier surface damage,and the easier introduction of defects on the surface,so bilayer tungsten disulfide is more likely to cause increased friction at low energy;?3?The untreated multilayer and bilayer tungsten disulfide have a significant decrease in friction and friction coefficient after annealing at 350°C and 500°C.The reason for the decrease may be that some organic molecules have been removed from the surface;?4?After the multilayer and bilayer samples with defects are annealed at 350°C and 500°C,the frictional force increases with the increase of annealing temperature,indicating that the temperature has little effect on the repair of defects,and the temperature is too high.Aggravation of surface modification of tungsten disulfide containing defects,resulting in increased friction and ultimately friction failure.