Study On Tribological Properties Of PTFE Matrix Composites In Sand-dust Environment

The bearing is usually lubricated with grease,but under special circumstances?ultra-low temperature,liquid nitrogen?the conventional lubrication method cannot be used,so the conventional lubrication method can only be replaced by the solid lubrication method with the self-lubricating cage.At the same time,China is a vast territory,is also one of the world's most desert or desertification land.Sand-dust particles will invade the internal system of the machine,destroy the stable operation of the machine system,causing a lot of losses.Therefore,it is of great value and significance to study the tribological properties of self-lubricating materials for makeself-lubricating cage in sand-dust environment.In this study,polytetrafluoroethylene?PTFE?matrix composites were prepared by adding nano-Serpentine and nano-La₂O₃.The effect of nano-Serpentine,nano-La₂O₃;and environmental factors;on the tribological properties of PTFE composites was investigated by orthogonal test.The mechanical properties of PTFE matrix composites were tested.The self-made sand-dust simulation device was used to improve the existing MMU-5G friction and wear tester,and the tribological experiment was performed using the improved test machine.The wear surface and transfer film morphology of the sample were observed by SEM and the wear mechanism was analyzed.The optimum matching of PTFE matrix composites was determined.The tribological properties of the composites with the optimal matching under different working conditions in the sand-dust environment were explored,and the best suitable working conditions were determined.The results show that the nano-Serpentine content has the greatest influence on the wear rate,hardness and elastic modulus of PTFE matrix composites.The friction coefficient of PTFE matrix composites is greatly influenced by the environmental factors.The wear mechanism of dry friction is mainly adhesive wear,and the wear mechanism in sand-dust environment is mainly abrasive wear.The tribological properties of PTFE matrix composites in two kinds of sand-dust environments,weak sandstorm and medium-intensity sandstorm,showed the same trend with different speed and loads,and the wear mechanism also changes from abrasive wear to adhesive wear with the increase of load and speed.When the load is 6.21 MPa and the speed is 0.24 m/s in the weak sandstorm environment,and when the load is 4.66 MPa and the speed is 0.48 m/s in the medium-intensity sandstorm environment,the PTFE matrix composites have the best tribological properties.