Research On Technology Of Micro-arc Oxidation Of Ti6Al4V Under Constant Current Condition

In order to improve antifriction and wear resistance of Ti6A14V,the thesis is about micro-arc oxidation of Ti6A14V,based on lots of experiments applying micro-arc oxidation parameter under constant current condition. Infulence of electronic parameters (current density, duty cycle,frequency) and time are studied on Ti6A14V coating thickness,surface and composition of phase in the Na₂Sio₃+Na₃Po₄ solution.Friction measured by abrasion machine, bond strength measured between coating and matrix by scratch tester.Analyzing wear resistance property of Ti6A14V of non-micro-arc oxidation and Ti6A14V after treatment of different electronic parameters and time after concentrated sulfuric acid treated.The result shows,the growth and structure of Ti alloy oxidation coating can be affected obviously by frequency ,duty cycle with constant current and oxidation time, current density influences the impulse voltage and coating thickness, and as current density increases,size of micropore becomes larger.XRD shows the oxidation coating is mainly composed of anatase and rutile TiO₂, the latter increses with the increase of the current density, amorphous phase formed as the entrance of Si and P into the coating. Duty cycle has a similar influence to the the growth and composition of micro-arc oxidation.With the increase of the impulse frequency, thickness turns lower,size of micropore on the coating suface becomes less,but numbers gradully increase .When frequency is lower than 500Hz,influence of impulse frequency is not so obvious to the relative content of anatase and rutile TiO₂,When frequency is more than 500Hz, content of anatase and rutile TiO₂ increase.Under constant current, oxidation time affects the growth and composition of Ti alloy obviously too,coating thickness increases with the extension of oxidation time.At the mean time,content of anatase TiO₂ decreases,while rutile TiO₂ gradually increases .Result of inspection shows, the treated Ti6A14V coating coefficient of friction is about 0.15,much less than the matrix 0.8, thus improves wear resistance property of Ti alloy after micro-arc oxidation. Under constant current condition ,bond between coating and matrix decreases with duty cycle increases; while gradually increase with extension of time and increase of frequency.As a result,the bond between coating and matrix is well. At the same time ,under different constant current condition, wear resistance property of Ti6A14V micro-arc oxidation coating improves obviously, but will decrease with extension of time, decrease of frequency and increase of duty cycle.