Study On Micro-arc Oxidation Process And Properties Of Ti6A14V Titanium Alloy

The effects of electrolyte composition, voltage, and oxidation time on the surfacemorphology and performance of Ti6Al4V alloy were studied by micro-arc oxidation （MAO）processes,using DC power supply and the electrolyte system which were composed ofNa₂SiO₃, Na₃PO₄and NaOH. The morphology and phase, binding force, roughness, oxidation,sulfuric acid corrosion resistance were investigated by using scanning electron microscope,X-ray diffraction, coating adhesion nick, roughness, anti-oxidation and sulfuric acid corrosionresistant analysis.With the increase of MAO time and voltage, the amount of pore decreased, the porediameter increased, the thickness and surface roughness of the coatings increased. Thebinding force of the coatings and the substrate increased with the increase of MAO voltageand time, the binding force increased from41.55N to119.65N when the voltage increasedfrom210V to300V. When the contant of NaOH （1g L）, the average friction coefficient wasthe lowest, it was only0.27215, while the friction coefficient of the Ti6Al4V alloy withoutmicro-arc oxidation treatment was up to0.6145.After cyclic oxidation for100h, the oxidation increasing weight of the alloy withoutMAO treatment was30.51mg/cm², while it was only3.7mg/cm²when MAO at60min for300V. The high temperature oxidation resistance increased with the increase of MAO timeand voltage. The increasing weight of oxidation decreased from7.56mg/cm²to3.7mg/cm²when the MAO time increased from10min to60min at300V, it was14.82mg/cm²when thesample was treated by MAO at60min for250V, while it was only3.7mg/cm²when thesample was treated by MAO at60min for300V. The result indicated that the anti-oxidationproperties of Ti6Al4V alloy was the best when the sample was treated by MAO at60min for300V.After soaking in sulfuric acid （30%） for36h, the weight loss of the specimen MAO at60min for300V was only3mg, while it was up to42mg in the specimen without treatment,the latter is14times of the former. When the treatment time increased from5min to60min,the weight loss of the coatings decreased from36mg to3mg, which decreased11times. Thecorrosion resistance of the coatings which was treated by using NaOH （1g L） was2times of the alloy without treatment, and the treatment specimen was superior to which was treatedwithout adding NaOH. The result indicated that the sulfuric acid corrosion resistance was thebest when the electrolyte contains NaOH （1g L） for60min.