Study On The Preparation Process Optimizations And The Properties Of LY12 Aluminum Alloy Micro-arc Oxidation Coating

Aluminum alloy has many good physical and chemistry properties,and is applied widely in all fields,but its low pole potential makes aluminum alloy bad anti-erode property,especially contacted with metals of high pole potential,it is easily eroded through spot-erosion.Although the natural oxide film on the aluminum has good anti-erosion property,because the natural film is very thin,and its rigidity is very low,It could not to prevent corrosion under adverse circumstances and could not prevent the destruction caused by friction.Surface treatment to improve its anti-erosion property is necessary in practical industrial appliance.Micro～arc oxidation is a new surface treatment Technology.Recently micro-arc oxidation is the technology of the surface treatment that has been developed in home and abroad,which can treat Aluminum alloy,Magnesium alloy and Titanium alloy.Because of the simple technical process and the predominant performance of treated surface,the applying prospect is very fine at home and abroad,SO the MAO study on Aluminum alloy has its important theoretical and practical significance.In this paper,the oxidation coating by MAO in single component electrolyte solution is investigated,reviewing the effects of every electrolyte concentration on the thickness,hardness,anti-erosion of oxidation coating,In the basis of Single component electrolyte experiment, using L₉(3⁴)orthogonal experiment,a good MAO composition of the electrolyte system for LY12 Aluminum alloy is found out:Na₂SiO₃:10g/L; H₃BO₃:4.5g/L;KOH:1g/L;H₂O₂:2g/L;temperature:25℃～50℃etc.Various processing parameters(including current density,Voltage,oxidation time,Electrical parameters etc.)are studied,and the best technical parameters is found:electric current density 10A/dm²,oxidation time 45min,electrolyte temperature＜45℃,Frequency 800Hz etc.This paper has analyzed the surface and cross-section morphology and the phase composition of the ceramic coatings by using XRD,SEM.The results show that coating mainly contain Al₂O₃,and is composed of the three-layer structure with transition layer,compact layer and loose layer. The substrate and coating penetrate each other,presenting metallurgy combination.At the same time inspected micro-oxidation of the ceramic film thickness,the bond strength etc.,Also inspected the micro-oxidation film properties before and after the change,and give the theoretical analysis.