Effect of albumin and peroxide in on corrosion of Zr and Ti alloys in physiological saline

摘要

It is known that the corrosion of Ti alloys is increased in the presence of peroxide species. This is a concern for metal implants in the body, since inflammatory processes can generate reactive oxygen species such as peroxide. However, there has been very little work investigating the effect of peroxide on corrosion of Ti alloys in the presence of proteins, which are a major constituent of extracellular fluid. Recent work has shown that the combination of peroxide and albumin, the most prevalent protein in relevant environments, can lead to increase release of metal ions over longer periods of time. This is surprising since albumin can act as a cathodic corrosion inhibitor. In the present work we show that the synergistic effect is a time-dependent process, giving opposite effects for periods of hours and days. The adverse effect of peroxide on corrosion of titanium can be mitigated by alloying with zirconium which prevents dissolution of the Ti passive oxide film. However, if the level of Zr is too high in the alloy, it can become susceptible to pitting corrosion. Preliminary work using synchrotron X-ray methods to investigate artificial pits in pure Zr has shown the release of Zr metal fragments during pitting corrosion, showing how electrochemical processes in the absence of mechanical effects can lead to metal fragments in tissue.