Research On Preparation And Sealing Treatment Of Micro-arc Oxidation Layer On 6061 Aluminum Alloy

Micro arc oxidation can effectively improve the wear resistance of aluminum alloy,but the micropores on the layer surface limit its application in long-term corrosion environment.In order to further improve the compactness and corrosion resistance of the micro arc oxidation layer,6061 aluminum alloy was used to prepare the micro arc oxidation layer and seal treatment.The micro arc oxidation layer was treated by adding cerium nitrate in electrolyte,post laser remelting and LDH in situ growth methods.The effects of cerium concentration,laser remelting power,LDH reaction concentration,temperature and time on the microstructure,phase composition,porosity and corrosion resistance of the coating were studied by means of metallographic microscope,SEM,XRD and electrochemical workstation.The main resultsare as follows:?1?Cerium nitrate can effectively reduce the porosity of the micro-arc oxide film and improve the compactness.The microporous micro-arc oxidation film layer is mainly composed of?-Al₂O₃,?-Al₂O₃and a small amount of Al₂Si O₅;Ce element is distributed in the film layer as Ce?OH?₄and Ce O₂.0.25g/L cerium nitrate micro-arc oxidation reduces pores and cracks,minimizes porosity and roughness,and has the best corrosion resistance.?2?With the increase of laser remelting power,the porosity of the micro-arc oxide film decreases.900W laser power remelts the micropores and cracks of the micro-arc oxide layer,effectively seals the defects in the film layer,and has the best corrosion resistance;the 1000W laser power micro-arc oxide film has a lower?-Al₂O₃content and an increased?-Al₂O₃content,which results in poor film and stress crack resistance.?3?As the concentration of Zn?NO₃?₂solution increases,the content and density of the Zn Al-LDH film layer first increases and then decreases;as the reaction temperature increases,the Zn Al-LDH film layer becomes more uniform and dense,with better crystallinity,The LDH at 100°C is a large sheet-like network loose distribution;with the increase of the reaction time,the uniform and dense Zn Al-LDH film layer is improved.When LDH is grown at 32 hours,the surface agglomeration phenomenon appears.0.05mol/L Zn?NO₃?₂,reaction temperature 80°C,reaction time 32h,Zn Al-LDH grows evenly and densely on the surface of micro-arc oxidation,effectively seals the micropores and cracks of the micro-arc oxidation film layer,achieves the effect of sealing,and resists corrosion Best performance.