Design,Preparation And Simulation Space Application Of MoS₂-C Composite Films

With the implementation of projects such as deep space exploration,grease lubricants are prone to evaporation,decomposition,or cross-linking under the harsh environmental factors of space,making it difficult to be competent for the lubrication of space machinery.For those with high precision,high stability,low vibration,low noise,and high transmission efficiency,as well as new space application superlubricity solid film materials and technologies with extremely low friction coefficient(10^-3magnitude)and ultra long wear life（>10⁷rpm）,there is an urgent need.Based on the research of graphene/molybdenum disulfide super-lubrication system in our group,this paper explores and designs MoS₂-C heterogeneous composite films to improve their tribological properties in vacuum environment,which guides the application direction of carbon-based composite films in vacuum and explores the influence of low temperature on the properties of MoS₂-C composite films,and discusses the low-temperature wear mechanism of the films in depth,which provides guidance for the application of MoS₂-C composite films in space.The main research content is as follows:1.By regulating parameters such as speed,Argon gas flow,graphite target current,the MoS₂-C composite film with optimal performance is prepared,and the film shows a dense"nano crystal/amorphous"structure.2.MoS₂-C composite film has excellent tribological properties in vacuum,and maintained ultra-low friction coefficient（0.006～0.009）and wear rate(1.026×10^-7mm³/N·m),reaching a super-lubricated state.During the friction process,carbon is selectively transferred to the surface of the steel ball to form an amorphous carbon transfer layer,and an ordered MoS₂（002）crystal surface is formed on the surface of the film wear mark,and friction occurs between the MoS₂ordered crystal and the amorphous carbon transfer film,forming non-public heterogeneous contact,reducing the friction coefficient to achieve superlubrication.3.The tribological properties of MoS₂-C films in different temperature environments of 50K,100K,200K and 300K were studied,and the influence of low temperature on the structural changes,mechanical properties and tribological properties of the films was discussed.The results show that the friction properties of the composite film gradually deteriorate with the decrease of temperature（the friction coefficient increases from 0.01 to 0.07,and the wear rate increases by 1.9 times）.During the friction process,the film hardens under 50K conditions,and there is a thick（about 60nm）friction layer composed of highly ordered crystalline MoS₂on the surface of the wear scar,and the internal MoS₂crystal changes from a highly ordered orientation parallel to the sliding direction to a random orientation,which inhibits the formation of a transfer film,while there is only a thin（about 5nm）friction layer on the surface of the wear mark under the condition of 300K,which makes it easy to generate a transfer film dominated by MoS₂and C on the dual sphere under the action of low shear force.The results show that the influence of low temperature on the tribological properties of MoS₂-C composite film is unfavorable.