Research On Key Technology Of Tribology System Of The Attitude Control Flywheel

To achieve longer life, better performance and higher reliability of the tribological system in demanding increasing more higher requirement of the attitude control flywheel for satellite, and furthermore to improve the life and the control precision of the satellite, the key factors and which influence the performance of the axle of the attitude control flywheel be studied in this paper.Aiming at the problem of the poor performance at low speed, the narrow range of the rotator when the flywheel lubricated with liquid lubricants, and the short lubrication life and poor antifriction while that lubricated with solid lubricant, for improve the performance of the fly wheel when work at start-up and low speed, and realize the low friction, wide speed range and accurate control, the solid lubrication coatings using with liquid lubricants simultaneously is proposed.Based on the theory of liquid lubrication and solid lubrication, and combined with the tribology and the surface and interface chemistry principles, the feasibility of solid lubricating coatings-oil composite lubrication was analyzed, and the performance and mechanism of solid lubrication film used with liquid lubricants was studied with experiment and theoretic based on the knowledge of material mechanics, tribology, surface and interface chemistry and hydrodynamic. First, the tribological modal of solid lubricating coatings-oil composite lubrication were established when the friction couples work at start-up, boundary lubrication, mixed lubrication and hydrodynamic lubrication, and antifriction mechanism of each model was analyzed. Then the tribological experiment were carried out on magnetron sputtered MoS2 coatings and chemical vapor deposited hydrogenated diamond-like carbon (DLC) films against Si3N4 ball using a ball-on-disk tribo-tester under the conditions of room temperature and different lubrication condition, and the influence of lubrication condition, speed and load to the tribology performance of solid coatings was analyze from the results of experiment, at the same time, the antifriction mechanism and antiwear property be studied too based on surface morphology of coatings, investigated by atom force microscope (AFM), and so as to provide theoretical and experimental basis for the applications of solid - liquid composite lubrication in flywheel.The results of theoretical analysis and experiment both showed that: The performance of friction couples be improved greatly when the solid lubrication film used with liquid lubricants simultaneously, the friction of the couple at start-up, boundary lubrication, mix lubrication and hydrodynamic lubrication be improved effectively, the improvement of the tribological performance at start-up and low speed could improve the reliability and control precision of the attitude control flywheel, and the decrease of the friction at high speed could reduce the power and prolong the life the satellite effectively. For the anti-friction performance of MoS2 better than DLC, the effect of MoS2 film to improve the zero-speed reversing and control precision at low speed of the flywheel better than DLC, but the anti-wear performance of MoS2 film be reduced by the liquid lubricants. While the anti-wear performance of DLC film be improved evidently and which could exert the advantage of solid lubricating coatings-oil composite lubrication chronically, and that is important to reduce the motor's power and increase the life of the flywheel.In order to analyze the loss of lubrication oil vapor in space and the influence of the oil loss to the lubrication life of attitude control Flywheel, the physical mode of the lubrication was established and the transfer of the oil molecule via by the seal gap was studied, and experimental of the selected oil volatilized in a simulant vacuum room, and the way to reduce the flow conductance of the shafting and the loss of oil vapor molecule was given through the comparative study of theoretical and experimental investigation, and then improve the lubrication life of the flywheel effectivly.To investigate the properties of critical failure of the Si3N4 hybrid ceramic ball bearing when the lubrication got worse, the characteristic of currents of driver motor and the wear surface morphology was analyzed after the tribology experiment of the test bearing rotating at the high speed to failure without lubrication was completed, the research would be useful to the critical performance of flywheel.