微弧氧化钛合金的电化学腐蚀行为

采用微弧氧化技术在TC4钛合金表面制备了多孔陶瓷层,研究了其在Hank′s模拟体液中的电化学腐蚀行为,利用SEM和XRD分析了其表面形貌和物相组成。结果表明,微弧氧化合金的自腐蚀电位升高约0.3V,提高了TC4钛合金在生物体液环境下的化学稳定性。在钛合金植入体电位范围内,微弧氧化处理可明显提高极化电阻,减少腐蚀电流1~2个数量级。随腐蚀时间的延长,TC4钛合金表面钝化膜逐渐发生腐蚀,而微弧氧化膜浸泡初期HA的形核及生长是电极反应中最活跃部分,2周后表面形成均匀的HA薄膜,表现出良好的抗电化学腐蚀性能。

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.