Research On Key Technology Of Micro Arc Oxidation Of Aluminum Alloy

Due to its environmental protection characteristics of processing and layers with ceramic feature,micro-arc oxidation technology is widely used in aerospace and automotive industry as a new surface modification technology.6061 aluminum alloy belongs to bestrengthened with heat treatment alloys,and is widely used in aerospace fixtures,communications,automated machinery parts,precision machining,electronics and precision instruments,and so on.Aluminum alloy’s integrated performance is somewhat improved after heat-treatment,but still can’t meet the application of many complicated conditions.Aluminum alloys by micro-arc oxidation treatment possess greatly improved hardness,wear resistance and corrosion resistance,due to its complex forming process and deficient hardness,wear and corrosion performance of micro-arc oxidation film,necessity of study on the micro-arc oxidation process more in-depth and film performance improvement increased.In this paper,experiment is used to improve the film properties by changing the electrical parameters and electrolyte system.Main electrical parameter of the research topic is current density,mainly discussed the impact of the current density pattern on the film properties;REE has a good application in surface modification of materials and surface treatment for its special electronic structure,electrolyte system is improved by adding REE Y,this paper mainly discussed the impact of rare earth element Y on micro-arc oxidation process and the corrosion resistance of the oxide film,thereby detecting the impact of pre-film prepared by the pretreatment method on micro-arc oxidation process.The main work and conclusions as follows:(1)Current density impacts greatly on the structure and properties of micro-arc oxidation ceramic membranes,respectively,a constant current density and ladder current density mode is adopted to prepare micro-arc oxidation ceramic coating,studied the effect of current density on the aluminum alloy micro-arc oxidation ceramic’s coating thickness,surface roughness,hardness and corrosion resistance,while the surface morphology and phase composition of the ceramic membranes were observed and analyzed.(2)REE is a good surface active element.This paper studyed the effects of different concentrations of rare earth elements Y on micro-arc oxidation by the use of heavy rare earth elements Y as an additive system.REE added to electrolyte promoted the micro-arc oxidation process,changed phase composition of the oxide film,refined micro structure of ceramic membrane structure more uniform and dense,while greatly improved the corrosion resistance.(3)In this paper,we get prefabricated aluminum film by the rare earth surface treatment and high temperature oxidation prior to treatment,and then studied their micro-arc oxidation film morphology and phase composition under different current densities,compared to the effect of non-pre-film,high-temperature membrane and rare earth conversion coating on micro-arc oxidation.The study found:pretreatment to rare earth conversion coating promotes the inner structure’s completeness of the oxide film and the full extent of binding between the film and the substrate,and further improves the performance of micro-arc oxidation film.