Study On Friction Self-organizing Behavior Regulation And Ultra-low Friction Of Diamond-like Films

Diamond like carbon?DLC?films are widely used as solid lubricants,which have excellent mechanical properties and tribological properties.In this paper,diamond-like carbon?DLC?films were prepared by plasma enhanced chemical vapor deposition?PECVD?.The structure and properties of DLC films were investigated,and the effect and mechanism of different temperature and load on the friction of DLC films were discussed.The main results are as follows:1.As the premise and basis of the research work,the structure of the coating equipment and the preparation process of the film are described.DLC films were prepared by PECVD.The microstructure,morphology,roughness,adhesion and tribological properties of DLC films were investigated.2.The effect and mechanism of different temperature on the friction process of DLC were studied.Using high resolution transmission electron microscope and Raman spectrum,we studied the structure evolution of debris and wear.In the temperature range below 150?,the increase of temperature promotes graphitization,accelerates the formation of graphene nanostructures,and reduces the friction coefficient.At 150?,there are more regular nanoscroll like graphene nanostructures in the debris,and the lowest frict ion coefficient is0.012.At 200?,the nanoscroll structure is disordered and the angle is sharp,which leads to the failure of ultra-low friction state.The results show that the temperature can change the fine structure of the graphene nanoscrolls,which ultimately determines the tribological behavior of DLC film.3.The effect and mechanism of different loads on the friction process of DLC film were studied.Through the influence of different loads on the friction process of Al₂O₃-DLC system,we found that the different loads mainly affect the contact area of the dual ball and DLC film.It is found that graphitization is the main reason for the decrease of friction coefficient.Through HRTEM observation and analysis of the micro morphology of the wear debris,it is found that graphitization also occurs at 20 N load,but the microstructure of the wear debris is not as regular as that at 5 N,which explains the reason why the super sliding can not be realized at 20 N.Through this experiment,we also get that the best suitable load of the film is5 N,at this time,the friction coefficient can be less than 0.01.