Study On The Triboelectrification And Tribological Properties Of PTFE-based Composites With Various Fillers

In this thesis,the triboelectrification and tribological properties of PTFE-based composites with various fillers sliding against 45 steel were studied.We experimentally studied the charges in triboelectrification voltage,the friction coefficient and wear of PTFE-based composites with various fillers under different conditions.The relationships between charges in triboelectrification voltage and friction coefficient,wear amount and friction transfer were analyzed.The wear mechanisms were also analyzed by using optical microscope and scanning electron microscope.It is of great theoretical and practical significance to explore the law of triboelectrification and tribological properties in order to control and optimize tribological properties of the composites.The main conclusions of this study are as follows:1.Effect of working conditions on triboelectrification of PTFE-based composites with various fillerThe charges in average triboelectrification voltage of the composites increased with the increase of load and velocity as a whole.Under the same speed,load and filler content,the charges in average triboelectrification voltage of the composites increased from low to high were:?Gr,MoS₂,CF?/PTFE,Gr/PTFE,?Gr,MoS₂,CF,GF?/PTFE,?Gr,MoS₂,CF,SiO₂?/PTFE,?Gr,MoS₂,GF?/PTFE?Notes:Gr refers to Graphite,CF refers to Carbon Fiber,GF refers to Glass Fiber?.In the?Gr,MoS₂,CF,GF?/PTFE composites,the charges in average triboelectrification voltage of the composites first increased and then decreased with the increase of GF content;in the?Gr,MoS₂,CF,GF?/PTFE composites,the charges in average triboelectrification voltage of the composites decreased with the increase of the CF content;in the?Gr,MoS₂,CF,SiO₂?/PTFE composites,the charges in average triboelectrification voltage of composites tended to increase with the increase of SiO₂content.In the case of the same total volume of the fillers,the charges in average triboelectrification voltage of the composites with a higher carbon content were lower than that of the composites with a low carbon content;furthermore,the charges in average triboelectrification voltage of composites containing more particulate fillers were generally higher than that of the composites containing fibrous fillers.2.Effect of working conditions on tribological properties of PTFE-based composites with various fillersThe average friction coefficients of the composites decreased with the increase of load or velocity,and their wear losses gradually increased with the increase of load or speed.In the?Gr,MoS₂,CF,GF?/PTFE composites,the average friction coefficient of the composites gradually increased with the increase of GF content,but the increase is lower,the wear loss decreased with the increase of GF content.In the?Gr,MoS₂,CF,GF?/PTFE composites,with the CF content increases,the average friction coefficient of the composites decreased and then increased gradually,the wear loss decreased with the increase of CF content,and suddenly increased when the CF content reached 10vol%.In the?Gr,MoS₂,CF,SiO₂?/PTFE composites,with the increase of SiO₂ content,the average friction coefficient of the composites gradually decreased first and then gradually increased,the wear loss with the increase of SiO₂ content first slightly decreased and then gradually increased.3.Correlation between triboelectrification and tribological properties of PTFE-based composites with various fillersAs a whole,the friction coefficient of the composites decreased with the increase of charges in triboelectrification voltage,their wear loss increased with the charges in triboelectrification voltage.The thickness of the transfer film on the counterfaces gradually increased as the charges in triboelectrification voltage increased;the weight percentages and atomic percentages of C,O,F and Si in the transfer film increased with the increase of the charges in triboelectrification voltage to some extent.