Optimization Of Preparation Process And Wear Resistance Of Micro-arc Oxidation Coatings On Titanium Alloy

Titanium and its alloys are widely used in aerospace,shipbuilding and other fields,but their low surface hardness and poor wear resistance limit their applications in the field of mechanical transmission.In order to expand the scope of its application,micro-arc oxidation coatings with good wear resistance was prepared on the surface of the TA2substrate by changing the electrolyte system and optimizing the micro-arc oxidation process parameters,and the wear resistance of the micro-arc oxidation coating under boundary lubrication conditions was explored.The performance of micro-arc oxidation coatings prepared in different electrolyte systems is quite different.Firstly,the wear resistance of micro-arc oxidation coatings prepared in single electrolytic system was studied.In the aluminate electrolyte system,the growth of the micro-arc oxidation coating consists of the oxidation of the substrate and the deposition of the electrolyte.The coating is composed of aluminum titanate,rutile and alumina,and the thickness and surface roughness of the coating are the smallest.But its hardness is maximum and wear rate is minimum.In the phosphate electrolyte system,the growth of the micro-arc oxidation coating is mainly the oxidation of the substrate,and the coating is composed of anatase and rutile.In the silicate electrolyte system,the growth of the micro-arc oxidation coating is mainly the deposition of the electrolyte.The coating is composed of amorphous silica,anatase and rutile.But its hardness is minimum and wear rate is maximum.Secondly,the wear resistance of the micro-arc oxide coatings prepared in the composite electrolyte system of aluminate and phosphate was explored.As the concentration of sodium phosphate increases,the thickness of the micro-arc oxidation coating increase,but the hardness decreases,and the wear rate increases.The micro-arc oxidation coating prepared in the aluminate electrolyte system has the best wear resistance.The optimal process of micro-arc oxidation was obtained by orthogonal experiment:voltage is 470 V,electrolyte concentration is 10 g/L,and oxidation time is 10 min.The thickness of the micro-arc oxidation coating prepared under the optimal process parameters is about 5.8?m,which is mainly composed of aluminum titanate,rutile and alumina.Under the condition of dry friction,the micro-arc oxidation coating mainly produces abrasive wear and adhesive wear,and its wear rate is 6.52×10^-6mm3N-1m-1.The effect of oil lubrication conditions on the friction and wear resistance of micro-arc oxidation coating was explored.The results show that when the micro-arc oxidation coating is in the boundary lubrication state,the friction coefficient of the coating is stable at about 0.13.When the grinding ball material is GCr15,the wear rate of the micro-arc oxidation coating under dry friction and boundary lubrication conditions is small.When the material of the grinding ball is Al₂O₃,under the condition of dry friction,the micro-arc oxidation coating quickly fails,and the wear rate is large.Under the condition of boundary lubrication,the service life of the micro-arc oxidation coating is improved,and the wear rate of the coating is small.