MoS₂/Cu Composite Electro-brush Coating Preparation And Vacuum Friction Performance

MoS₂has layer structure, in which the chemical bond between layer and layer isweak van der Waals forces so that it is easy to shear and slip, resulting in the excellentlubricating property. In this thesis, MoS₂/Cu composite coating was successfullyprepared by brush plating technology using the mechanical and chemical dispersionmethods. The phase composition、morphology、structure and chemical constitution ofcomposite coating samples, obtained under different contents of molybdenum disulfideand brush plating voltages, were analyzed by XRD、SEM、energy spectrum analysis（EDS） and transmission electron microscope （TEM）.The bonding strength、microhardness、electrical conductivity of composite coatings under different preparationconditions were evaluated and the friction and wear behaviour was also detected byGTM-3E vacuum tribometer.The results show that MoS₂/Cu composite coating can be successfully preparedusing the brush plating technology. The main phases of the composite coating are Cu andMoS₂. No other phase was observed in the plated coating. The optimal parameters werebrush-plating voltage of8v and the MoS₂concentration of15g/L，respectively. Underthe optimal conditions, the obtained coating is densification and good bonding.Molybdenum disulfide particles were homogeneously distributed and porosity wasapproached to zero. TEM analysis indicated that MoS₂particles in the plated coatingkeep the original morphology, and the interface between Cu and MoS₂particle is clear.Because of the movement of the plating pen on the substrate surface during the brushplating process，molybdenum disulfide displays preferred deposition orientation （002）,which is parallel to the surface of plated coating. The bonding strength andmicrohardness of plated coating decrease as the increase of MoS₂concentration inplating solution. Under the optimal conditions, the microhardness and the bondingstrength are20N and130HV0.05/10, respectively. The maximum electrical conductivity ofplated coating without vacuum heat treatment is55.2%IACS, the average value is43.9%IACS. The study of wear and friction behavior demonstrates that MoS₂/Cu compositecoating has good friction and wear performance in vacuum environment. The frictioncoefficients of plated coating under different experiment conditions is in the range of0.025-0.1, which can be attributed to the formation of MoS₂lubrication transfer filmduring the friction process. The main wear mechanism of composite coating is abrasivewear. With the increase of speed and load, friction coefficient was reduced, however thewear rate was observed increased.