Evaluation And Analysis Of PTFE-based Composites Transfer Film Morphology And Influence Of Tribo-electrification

In this paper,PTFE-based composites were prepared with graphite and MoS₂ as fillers.The transfer film formed on the steel surface was studied when the PTFE-based composites slid against 304 stainless steel.The formation process of the transfer film and its morphology characterization were investigated.At the same time,the law of tribo-electrification of the friction couple was studied.The morphological parameters of the transfer films formed under different conditions were correlated with the tribological properties of the composites.And a quantitative transfer film method was proposed.The friction and wear mechanisms of the transfer film were also analyzed.In addition,the effects of different test conditions and filler content on tribo-electrification were investigated,and the tribo-electrification properties were correlated with the tribological properties of the composites.In our work,the main conclusions are listed below:1.Effect of friction conditions on the transfer filmThe effect of friction time:In the friction process,the coverage of the transfer film formed on the counterface decreased briefly from 15s to 45s,and then increased gradually from 1min to 35min.It reached a relatively stable state in about 20min,after which the coverage did not change much,and finally maintained at about 88%.At the beginning of sliding,the polymer began to wear violently,and a thick transfer film was formed on the surface of the steel plate in a very short time?15s?.Then the transfer film thickness gradually decreased with time,and finally reached a relatively stable stage and fluctuated in a small range.The effect of load and velocity:With the increase of load,the coverage of the transfer film shows an increasing trend on the whole.The thickness of the transfer film under different loads varied little,and the effect of load on the thickness was not obvious.With the increase of the speed,the coverage of the transfer film shows a trend of decreasing first and then increased.The coverage of the transfer film was the lowest when the speed was 0.4m/s,which was only 84.85%.The effect of velocity on the thickness of the transfer film was very obvious,the thickness increased with the increase of velocity and the linear correlation was very strong.Gr and MoS₂ have similar effects on the morphology parameters of the transfer film.The increase of their content was beneficial to increase the coverage of the transfer film,and decrease the thickness of the transfer film.2.Effect of friction conditions on friction coefficient and wear rateWith the increase of load,the friction coefficient decreased and the wear rate increased.With the increase of velocity,the friction coefficient decreased gradually with time and the wear rate increased gradually.But the wear rate increased slowly when the velocity was less than 0.4m/s and increased sharply when the velocity was greater than0.4m/s.The increase of Gr and MoS₂ content can reduced the wear rate of the composites,and the reduction of MoS₂ was more obvious.The friction coefficient of composites decreased with the increase of Gr content,but increased slightly with the increase of MoS₂ content.3.Effect of tribo-electrification on transfer film and tribological propertiesThe transfer film coverage increased with the increase of tribo-electrification voltage,but the thickness of transfer film decreased first and then increased on the whole.The friction coefficient of composites decreased with the increase of tribo-electrification voltage,and the larger the voltage was,the faster the friction coefficient decreased.The wear rate increased with the increase of tribo-electrification voltage.4.Relationship between transfer film morphology parameters and friction coefficient and wear rateThe friction coefficient decreased slowly with the increase of transfer film coverage.There is a good correlation between the wear rate and the transfer film coverage,and the wear rate decreased gradually with the increase of transfer film coverage.The friction coefficient decreased with the increase of transfer film thickness.The wear rate decreased with the decrease of transfer film thickness,and changed rapidly when the transfer film thickness was thick.