| Titanium alloy are widely used in fields such as aerospace,shipbuilding,and health care due to their excellent comprehensive performance.However,the performance of titanium alloy materials facing complex wear and corrosion issues in complex marine environments is not ideal,which restricts the wider application of titanium alloy in marine environments.Micro-arc oxidation(MAO)technology is a solution environmentally friendly,simple to operate,and can in-situ grow a coating of high-hardness and dense metal oxide coating with porous morphology on metal surface,which helps to improve the corrosion resistance?and wear resistance of metals.Fluorocarbon resin(FEVE)has good corrosion resistance and stain resistance,and also has a good barrier effect on the penetration of some gases and liquids.In order to further improve the wear resistance and corrosion resistance of titanium alloy in marine environments,micro-arc oxidation layer was prepared on the surface of titanium alloy and orthogonal experimental was used to study the morphological variation law of micro-arc oxidation coating under different electrical parameters,and the micro-arc oxidation/fluorocarbon resin composite coating was prepared based on micro-arc oxidation coating.With the help of scanning electron microscopy(SEM),energy spectrometer(EDS),eddy current thickness gauge,friction and wear experiment in simulated seawater,immersion corrosion experiment,polarization curve and electrochemical impedance experiment,the micromorphology,element composition,thickness,wear resistance and corrosion resistance of micro-arc oxidation/fluorocarbon resin composite coating in simulated seawater were studied,and the following main conclusions were drawn:(1)In the silicate solution system,voltage is the biggest influencing factor for the parameters of titanium alloy micro-arc oxidation surface morphology,as the voltage increases from 350 V to 500 V,the average porosity of the micro-arc oxidation coating increases from13.79%to 38.43%,the average pore size increases from 1.00μm to 4.25μm,the number of micropores is reduced from 0.056/μm~2 to 0.012/μm~2,and the thickness of the coating is increased from 3.37μm to 15.16μm.The micro-arc oxidation time has a great influence on the average pore size of the coating,and its range is 1.40,and the average pore size of the film layer increases from 1.791μm to 3.191μm with time.The duty cycle and frequency have a certain influence on the number of micropores and the thickness of the film layer,respectively,but do not occupy a major influence compared to the voltage.(2)The fluorocarbon resin coating in the micro-arc oxidation/fluorocarbon resin composite coating completely covers the microporous structure on the micro-arc oxidation coating,and a fluorocarbon resin coating of about 13μm is formed on the surface of the micro-arc oxidation coating,so that the surface of the composite coating presents a dense fluorocarbon resin layer with a smooth and flat surface.With the increase of the pore size of the micro-arc oxidation coating,fluorocarbon resin is easier to penetrate into the micro-arc oxidation coating to form a mechanical interlocking structure,which can effectively improve the bonding force between fluorocarbon resin and micro-arc oxidation coating,and the micro-arc oxidation sample prepared by 500V,400Hz,3%,13min electrical parameters has the best composite film adhesion force of grade 0 adhesion by the delineation method.The addition of fluorocarbon resin can effectively reduce the friction coefficient and improve corrosion resistance,and the micro-arc oxidation coating can significantly improve the bonding ability with titanium alloy and fluorocarbon resin.The immersion experiment of micro-arc oxidation/fluorocarbon resin composite coating shows that the adhesion between the fluorocarbon resin film layer and the micro-arc oxidation coating is an important factor affecting the corrosion resistance of the composite film layer in the presence of scratches in the film layer.(3)The preparation of silane coating on the surface of the micro-arc oxide coating can effectively improve the barrier ability of the composite coating to the corrosive medium and thus improve the corrosion resistance of the substrate.The silane coating penetrates and completely covers the surface of the micro-arc oxide coating and forms a dense and flat silane coating on it,and presents a good adhesion with the micro-arc oxide layer.However,due to the poor physical properties of the silane itself,it will crumble or even peel off because of external mechanical forces.Base on the good adhesion of the Silane between both micro-arc oxide coating and fluorocarbon resin coating,it can be used as an intermediate layer to prepare the composite coating of micro-arc oxide/silane/fluorocarbon resin to effectively avoid the shortcomings of the Silane layer and improve the corrosion resistance of the composite coating. |
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