Study On Self-lubricating Properties And Tribological Mechanism Of Friction Interface Based On Lightweight Alloy

For improving the tribological behaviors of lightweight alloy substrate materials and prolonging service life of their components,based on light alloy base material as the research object,the composite solid lubricants and light alloy base self-lubricating materials were prepared;the types and mass fraction of solid lubricants,loads and temperatures on the influences of tribological properties of lightweight alloy base self-lubricating material interface were studied;the lubricating film formation on the influence mechanism of lubrication behavior of lightweight alloy base self-lubricating materials was explored.The conclusions are as follows:（1）Spherical graphene-silver solid lubricant was prepared by using flame spray welding;Ti-Al self-lubricating materials with graphene-silver were fabricated by applying spark plasma sintering;Ti-Al self-lubricating materials were characterized via using field emission scanning electron microscope,energy dispersive X-ray spectrometer,X-ray diffractometer,electron probe;the influence of temperature on tribological properties of Ti-Al self-lubricating materials was studied.The results showed that silver-coated graphene at 450℃was beneficial to the coordination of graphene and silver during lubrication.Low hardness lubrication film in grain refining layer was beneficial to the improvement of friction and wear performance.（2）Spherical Sn Ag Cu-Al₂O₃solid lubricant was fabricated by flame spray welding,and Ti-based self-lubricating materials containing Sn Ag Cu and Al₂O₃were prepared using spark plasma sintering.The Ti-based self-lubricating materials were characterized through field emission scanning electron microscopy,energy dispersive X-ray spectrometer,electron probe,and the effects of lubricant types and mass fractions on their tribological properties were studied.The results indicated that Ti-based self-lubricating materials exhibited excellent friction and wear behaviors under the co-lubrication of 12.0wt%Al₂O₃and15.0wt%Sn Ag Cu.Owing to the low strength of Sn Ag Cu,the lubrication film was prone to plastic deformation,which reduced the bonding force between Al₂O₃and friction surface and accelerated rotating motion of Al₂O₃particles,thus reducing the friction coefficients and wear rates.（3）Sinusoidal micropores were prepared on the titanium alloy surface.The Mg Al,Mg Al-graphite,Mg Al-graphene,and Mg Al-carbon nanotubes were filled with micropores at high temperature for preparing microchannels.The microchannels were characterized by employing Field emission scanning electron microscope,energy dispersive X-ray spectrometer,X-ray diffractometer,electron probe,three-dimensional morphometer,and the tribological behaviors of the microchannels at high temperature were studied.The results showed that the self-healing behavior and adjustment function of Ti-Mg Al were improved,and the friction coefficient and wear rate were reduced at 420℃compared to pure Ti alloy.Compared with Ti-Mg Al alloy,Ti-Mg Al-graphite,Ti-Mg Al-graphene,and Ti-Mg Al-carbon nanotubes had synergistic function and improved the friction and wear behaviors.Among which,the Ti-Mg Al-carbon nanotubes exhibited the best tribological properties.During wear,carbon nanotubes enhanced the enrichment degree of Mg Al,repaired surface cracks,and improved the self-healing function of the friction interface,thus improving the tribological behavior.（4）Spherical Sn Ag Cu-Al₂O₃solid lubricant was prepared using flame spray welding,and Ti base coatings containing Sn Ag Cu and Al₂O₃were fabricated by spark plasma sintering.The Ti base coatings were characterized by field emission scanning electron microscope,energy dispersive X-ray spectrometer,electron probe,transmission electron microscope,and the effects of loads and temperatures on tribological properties of the Ti base coatings were studied.The results showed that Ti base coatings containing spherical Sn Ag Cu-Al₂O₃had low friction coefficient and wear rate under a load of 16 N.Al₂O₃was closely coated with Sn Ag Cu,and a Sn Ag Cu enrichment film was formed between Al₂O₃and matrix.Sn Ag Cu produced plastic deformation and promoted friction rolling of Al₂O₃,which rendered the coating to exhibit excellent tribological properties.Additionally,at 235℃,the Ti base coating with spherical Sn Ag Cu-Al₂O₃exhibited small friction coefficient and wear rate.The 235℃was close to the melting point of Sn Ag Cu（240℃）,which led to the formation of a Sn Ag Cu enrichment film with plastic deformation ability,and made Al₂O₃produce good friction rolling,thereby resulting in an excellent lubrication ability of coating.