Study On Friction And Wear Mechanism Of PTFE Composites With Circular Texture Surface

Surface texture has been widely used in the field of tribology for its exceptional performance such as reducing friction,alleviating wear,improving lubrication and increasing bearing capacity,making it become an effective way to solve the problems of friction and wear of materials.However,for the frictional pairs which are composed of polymer materials and metals,the effect mechanism of surface texture on their tribological properties is still unclear.Intensively studying the effect of the counterpart surface micro-texture on the friction transfer properties and transfer film formation of polymer composites can provide a basis for the development of friction pairs with excellent performance.In this paper,circular textures with different parameters were prepared on the surface of 304 stainless steel by laser surface processing technology.The effect of circular texture on the tribological properties of PEEK and nano-SiO₂ filled modified PTFE composites under dry friction conditions was studied by LSR-2M reciprocating friction and wear tester.The surface of friction,morphology of transfer film,distribution of elements and morphology of wear debris of the composites were characterized.The effect of the interaction of test parameters on the tribological properties of circular texture friction pairs was studied by response surface method.The action mechanism of micro-texture on the counterpart surface of friction pair is deeply explored from the microscopic perspective,and the main conclusions are as follows:（1）The tribological properties of PTFE composites can be effectively improved by filling both PEEK and nano-SiO₂ alone,and the tribological properties of PTFE composites can be synergistically improved by combining the two fillers,so that the friction coefficient of the composites can reach a stable stage quickly.The roughness of the counterpart surface has a significant impact on the tribological properties of the composite.On the relatively rough counterpart surface,nano-SiO₂ is conducive to promoting the formation of the transfer film and making the surface of the transfer film smoother.（2）The friction and wear properties of PTFE composites can be effectively improved by selecting appropriate counterpart surface texture parameters.The pit texture with a diameter of 600μm,a depth of 5μm and a density of 20%has the best wear reduction effect,and the volume wear rate of the composite is 6.66×10^-6mm³/（N·m）,which is 35.7%lower than that of the untextured surface.The surface texture reduces the size of wear debris and improves the retention rate of debris.The larger,shallower and rarer texture is more conducive to the formation of uniform and complete transfer film on the counterpart surface,thus effectively reducing the wear of composite materials.（3）The friction and wear of composites are correlateed but relatively independent,and it is difficult to minimize the friction coefficient and volume wear rate at the same time under one test condition.The interaction among load,speed and sliding distance affects the friction and wear properties of PTFE composites on the textured surface of the pair.The larger load and speed will increase the wear of the composite in a short time.However,with the continues friction process,the larger load and speed can bring the debris collected in the pits out of the friction interface more effectively,and promote the formation of a uniform,complete and high coverage transfer film on the counterpart surface,which effectively improves the friction and wear performance of the composite materials.