Preparation And Tribological Properties Of Microarc Oxidation-electrophoresis-electroplating Composite Films

Titanium and its alloys are important lightweight structural materials,but their poor tribological properties severely limit their application range.Although micro arc oxidation(MAO)treatment can significantly improve the wear resistance of titanium metal,the surface of MAO film is porous and has high friction coefficient,which needs to be improved.Therefore,in this study,three kinds of antifriction and wear resistant composite coatings,namely,MAO-G,MAO-G-CEP and MAO-G-Ni,were prepared on the surface of titanium metal by using micro arc oxidation,electrophoretic deposition and electroplating technologies.The micro structure and tribological properties of the prepared composite coatings were systematically studied,providing a reference for the application of micro arc oxidation coatings and graphite materials in the field of tribology.Firstly,MAO-G composite film were prepared by micro arc oxidation and electrophoretic deposition techniques,and their microstructure and tribological properties were studied.The results indicate that with the increase of graphite coverage on the MAO surface,the anti-friction performance of the MAO-G composite film improves.When the coverage reaches 100%,the friction coefficient is the lowest.However,due to the weak adhesion between graphite particles and films,the wear resistance of the composite film is poor.Secondly,a MAO-G-CEP composite film was prepared by using cathodic electrophoretic paint to assist in the electrophoretic deposition and fixation of graphite particles on the MAO film,and its microstructure and tribological properties were studied.The results showed that the bonding strength of the MAO-G-CEP composite film was improved compared to the MAO-G film,and the friction coefficient of the MAO-G-CEP composite film was more stable over a long friction distance,maintaining between0.15～025,and the service life was significantly increased.In addition,the tribological properties of composite films prepared under different concentrations of graphite particles,MAO time,and electrophoretic deposition time were investigated.Among them,the concentration of graphite particles has the greatest impact on the friction coefficient of the composite film.As the particle concentration increases,the friction coefficient first decreases and then increases.When the particle concentration is 6g/L,the friction coefficient of the film is the lowest.Finally,the MAO-G-Ni composite film was prepared in two steps using electrophoretic deposition of graphite and nickel electroplating technology,and its microstructure and tribological properties were studied.The results indicate that the electroplating time has a significant impact on the microstructure morphology of the nickel film and the tribological properties of the MAO-G-Ni composite film.With the increase of electroplating time,microsphere like metallic nickel gradually forms a continuous cellular nickel film on the surface of graphite particles.The friction test results show that the friction coefficient of the MAO-G-Ni composite film electroplated with nickel for 10 minutes is the lowest,maintaining between 0.1～0.2.Furthermore,the friction coefficient of the MAO-G-Ni composite film is lower than that of the MAO-G-CEP composite film.