Research On Combined Film Fabrication Technology For 6061 Aluminum Alloy Based On Moving Cathode Micro-arc Oxidation

6061 aluminium alloy has good plasticity,high specific strength and specific stiffness,so it is widely used in aviation,aerospace,shipping and other military fields as well as automotive and other industrial fields.Aluminum alloy is prone to wear and corrosion in actual use.Because the naturally generated protective film on aluminium alloys cannot meet the requirements,surface treatment technology is necessary to increase the performance of the surface film.As a result,high performances of the film thickness,hardness,and surface roughness of the substrate material of the components are required.Micro-arc oxidation technology allows for the in-situ formation of ceramic oxide layers on aluminium alloy substrates,satisfying the strict requirements of material wear and corrosion resistance in aviation,aerospace and other fields.The traditional immersion micro-arc oxidation technology has strict requirements on power supply,working environment and other conditions.In this study,a small and portable moving cathode micro-arc oxidation device is used.On this basis,laser is used to assist the dynamic cathode micro-arc oxidation to improve the performance of micro-arc oxidation film.The design of the moving cathodic micro-arc oxidation device was performed using CATIA software.The device is made up of a cathode fixing system,a moving cathode system,an electrolyte recovery and filtration system,a stirring device system,a circulation system,and a cooling system.The feasibility of the device was tested,the micro-arc oxidation experiment was carried out with CNC system,and the moving speed of the moving cathode was optimized using the equivalent time method of fixed-point experiment.The moving cathode micro-arc oxidation experiment was carried out based on the 10minutes fixed-point micro-arc oxidation experiment,and a ceramic oxidation film with the thickness of 30.8?m and the surface roughness of 2.121?m was fabricated.Under the condition of moving cathode,the surface roughness and thickness of the oxide ceramic layer were used as performance indexes in the micro-arc oxidation experiments using 6061 aluminum alloy,and the electrical parameters during the experimental process were studied and optimized using the orthogonal experimental method.The experimental results showed that the electrical parameters affecting the thickness and surface roughness of the oxide ceramic layer were ranked as power supply forward voltage(29)current density(29)positive duty cycle(29)pulse frequency;after comprehensive analysis of the experimental results,the optimized power supply parameters were:power supply forward voltage was 550V,current density was12A/dm~2,forward duty cycle was 20%,and pulse frequency was 300Hz.Under the condition of moving cathode,the response surface curve method was used to study and optimize the electrolyte parameters during the experimental process,using the surface roughness and thickness of the oxide ceramic layer as the performance index for micro-arc oxidation experiments using 6061 aluminum alloy.The experimental results showed that the performance of the film layer was better when the Na₂Si O₃ concentration was 11.77g/L,Na OH concentration was 6.19g/L and Na F concentration was 2.14g/L and it was verified experimentally.Under the condition of moving cathode,based on the optimized experimental parameters,laser pretreatment was performed before the microarc oxidation experiment,and the microarc oxidation ceramic layer was processed on the basis of pretreatment with a scan spacing of 0.05mm,which was compared with the ceramic layer prepared in the conventional way.The thickness of the unprepared film layer was less than that of the composite film layer by about 10?m,and the microhardness was able to reach 2350HV,and the laser pretreatment prepared The thickness and microhardness of the composite layer prepared by laser pretreatment are both superior to those of the ceramic layer prepared by conventional methods.