Preparation And Tribological Behaviors Of Micro-arc Oxidation Composite Coatings On Titanium

Due to the poor tribological properties of titanium and its alloys,MAO?micro-arc oxidation?composite ceramic coatings with excellent tribological properties were prepared on the surface of TA2 titanium using direct recombination technology and indirect recombination technology of micro-arc oxidation,dipping and sintering treatment.The wear-resistant of TiO₂/SiC composite ceramic coating was prepared by directly adding the wear resistant particles of SiC?0.5⁰.7?m?with various content in the electrolyte.The microstructure and morphology of the single component MAO ceramic coating was changed,and its wear resistance was further improved.Through the combination of dipping and sintering process,a layer of self-lubrication anti-friction PTFE materials was coated on the surface of MAO ceramic coating.MAO-PTFE self-lubricating composite coating with excellent tribological properities was prepared.The morphology and microstructure of composite ceramic coating was investigated using SEM,XRD,EDS and Raman.The tribological properties of composite ceramic coating were measured by means of CSM ball-on-plate reciprocating tribometer,Mahr surface profiler,confocal microscope and SEM.TiO₂/SiC wear-resistant composite coating was fabricated by adding SiC particles in the electrolyte.Results show that adding SiC particles in the electrolyte has no significant influence on the micro-arc oxidation arcing voltage,and the thickness of the ceramic coating was basically the same as that of MAO coating.The SiC particles introduced into the ceramic coating effectively filled the micro-pores on the surface of the MAO coating,making the surface of the MAO coating become smooth and compact.With the increase of the content of SiC particels in the electrolyte,the surface compactness of the composite ceramic coating was improved.According to XRD analysis,MAO composite ceramic coating was mainly composed of anatase TiO₂ phase,rutile TiO₂ phase and SiC phase.The results of friction and wear test show that SiC particles introduced into MAO coating significantly reduced its wear rate.When the content of SiC particles in the electrolyte was12 g/L,the wear rate of the composite ceramic coating was reduced by 1/4.The self-lubricating MAO-PTFE composite coating was successfully fabricated on the titanium surface by the combined methods of micro-arc oxidation,dipping and sintering.Results show that PTFE materials formed a continuous whole through melting diffusing in the process of sintering,and the PTFE coating was evenly distributed on the surface of the MAO ceramic coating.PTFE materials effectively filled the micro-pores of MAO coating,reducing the porosity and surface roughness of the MAO ceramic coating.The friction coefficient of self-lubricating MAO-PTFE composite coating was only 0.1.The fabricated MAO-PTFE composite coating,integrating the advantages of wear-resistace of the MAO ceramic coating and the self-lubricating of PTFE materials,showing excellent anti-friction performance.