关键词: 超低温环境, 固体润滑, 涂层材料, 摩擦磨损

Abstract: The friction characteristics of silver (Ag),polytetrafluoroethylene (PTFE) and molybdenum disulphide (MoS₂) coatings were tested under different contact stresses and different sliding speeds using a high-speed rotary friction and wear tester in an ultra-low temperature liquid nitrogen (LN₂) environment.The shape of the wear marks and the main components of the steel discs were analysed using an XM-200 surface morphometer,a JSM-7800F scanning electron microscope (SEM) and an energy spectrometer (EDS),and the friction factors and wear mechanisms of the three coatings were investigated under ultra-low temperature environment. The results show that the friction factor of the coated steel discs does not vary much under two speeds (high sliding speed of 2 m/s and low sliding speed of 0.4 m/s),while the friction factor of the uncoated steel discs is influenced by the sliding speed,with MoS₂ and PTFE having the best friction reduction effect.The wear of the three coatings increases with increasing load for the same operating conditions.The wear resistance of PTFE in the ultra-low temperature environment is poor and the wear amount is higher,while the wear amount of steel/MoS₂ coating is the smallest and steel/Ag coating is the second,indicating that both Ag and MoS₂ show good wear resistance in the ultra-low temperature environment and the wear amount is smaller.

Key words: cryogenic environments, solid lubrication, coating materials, frictional wear