The Preparation And Tribological Properties Of MoS₂(C/Cr/Ti) Composite Films

MoS₂ film was widely used in equipment and mechanical processing because of its low friction in vacuum and inert gas.However,pure MoS₂ film can easily fail in high humid environment due to its high chemical activity of oxygen and low wear resistance durability,which greatly limits the expansion of using scope.The addition of metals or oxides to improve the properties of MoS₂ had made some achievement,and current studies of MoS₂ matrix were mainly focused on the single component,while the system research of the structure and tribological properties of multi-component MoS₂ based films were rarely reported.Hence,studies on MoS₂ based multicomponent films were mainly to improve the performance of MoS₂ film as well as keeping the positive function of doping single element.MoS₂(C/Cr/Ti)composite films were deposited by closed field unbalanced magnetron sputtering system.The content of each elements in composite films was controlled by their target currents.The composition and microstructure of the MoS₂(C/Cr/Ti)composite films were investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),atomic force microscope(AFM),transmission electron microscope(TEM),and X-ray photoelectron spectroscopy(XPS).The microhardness and tribological properties of as-deposited films were characterized by nano-indentation testing and ball-on-disk testing.The effect of different MoS₂ target currents and different Ti target currents of MoS₂(C/Cr/Ti)composite films on the microstructure and tribological behaviors were discussed.The results showed that MoS₂(C/Cr/Ti)composite films with dense structure were periodic layered amorphous nature.Among as-deposited films,MoS₂(C/Cr/Ti)composite film with low MoS₂ target current presented amorphous embedding some Cr₃C₂ nanocrystallites and higher hardness due to its high C content.With the increase of MoS₂ target current,the crystallinity and hardness of the composite films decreased.While the hardness of the composite films increased with the increase of Ti target current,and the hardness of as-deposited films(7.5-11.8 GPa)were higher than pure MoS₂ and MoS₂-Ti films.Additionally,the addition of C,Cr and Ti effectively decreased the roughness of the composite films,and the roughness of films with low Ti content was lower than the ones with high Ti content.MoS₂(C/Cr/Ti)composite films with low friction coefficient would be applied in various humid environment.Especially,the MoS₂(C/Cr/Ti)composite films(IMoS₂=1.8 A,ITi=0.3 A,Ic=2.5 A,Icr=0.2 A)exhibited stable and low friction coefficient(about 0.1)not only in different humidity air conditions but also in oil environment,and no delamination was found in the corresponding wear track after sliding 2500 s,and the wear rate of the film was about 1.5×10-16 m3/Nm.