Metal Dissolution and Repassivation of Ti-6Al-4V Alloy during Rapid Elongation in Simulated Body Fluid including Osteoblast-like Cells

The dissolution and repassivation of Ti-6Al-4V alloy in simulated body environment were examined using a straining electrode test. Samples were elongated with rapid straining rate of 0.67 s-1 in a-MEM+10 % FBS including proteins and osteoblast-like cells. The transient of current was recorded during and after elongation. For the charge density after elongation, the larger charge density was recognized on the sample immersed longer in simulated body fluid and the sample covered with cells. This result indicates that the proteins and cells adhered on the sample surface hinder the repassivation. When proteins or cells absorb on the sample surface, an occluded space is formed between proteins and cells and metal surface. Since the diffusion is blocked and the pH becomes low in this space, the repassivation is hindered. In addition, the current stagnation occurred during repassivation and a localized corrosion occasionally occurred along slip step on samples with cells.