Study Of Growth Mechanism And Technology On Micro-Arc Oxidation Of Mg Alloy

In this paper, AZ31 magnesium alloy ceramic coating was studied using home-made WH-1A micro-arc oxidation(MAO) equipment. MAO process and effects on ceramic coating using ultrasonic wave were studied by observeing arcing process and the changing on electrolyte around the sample in an anechoic chamber. Eletrolytes was improved on the base of Corrosion Resistance of MAO ceramic coating for magnesium alloy.The properties variation of MAO eletrolytes was tested by conductivity meter and pH meter. The stablest electrolyte parameters can be prepared based on the difference in property of eletrolytes. SEM, EDS, XRD were used to investigate the construction, morphology, phase composition. Additional agent could improve ceramic coating property. Compared ceramic coating corrosion resistance by immersing experiment and polarization curve measurement, the best MAO processing parameters of corrosion resistance was found,which improved coating property to reveal the action of energy during the micro-arc oxidation process.It was found that transition process had apparently effects on corrosion of MAO coating. Material of MAO discharge sintering were prepared with electrolysis products. Due to solutions on the corrosion rate too quickly or voltage on the discharge sintering too low,thus Metal surface corroding and decreasing coating formation.On the condition of ultrasonic wave, morphology changed,density increased, Laws of different material was all the same. With addition of different Kinds of rareearth salt in eletrolytes,the change of eletrolytes property and MAO process were different. With appropriate rare earth salt addition,MAO process could be stabley,which decreased striking voltage and increased coating growth speed.Addition potassium fluorozirconate introduced Zr element into coating. Introducing F element improved surface roughness and brightness.SEM showed that addition improved surface morphology, decreased hole size, increased density. Polarization curve measurement showed that potassium fluorozirconate improved coating corrosion resistance.