Electrochemical Corrosion Behaviors of Micro-arc Oxidation Titanium Alloy

The porous ceramic layer was prepared on the surface of Ti6Al4V (TC4) alloy by a micro-arc oxidation (MAO) method. The electrochemical corrosion behaviors were investigated in the condition of Hank's simulated body fluid. The surface morphologies and phases were analyzed by SEM and XRD. The experimental results show that the free corrosion potential of MAO TC4 alloy increases by about 0.3 V, resulting in improving the chemical stability of TC4 alloy in the biological fluid environments. In the potential range of the titanium alloy implants, the MAO treatment can increase the polarization resistance and reduce the corrosion current by one to two orders-of-magnitude. With the increasing of the corrosion time, the passive film on the surface of TC4 alloy is gradually corroded in Hank's simulated body fluid. The nucleation and growth of HA is the most active part of the electrode reactions for MAO layer at the early immersion. After two weeks, the uniform HA film will form on the surface of MAO TC4 alloy, which shows the good electrochemical corrosion resistance.