Characteristics of copper corrosion in simulated uterine fluid in the presence of protein

In order to acquire more knowledge of the performance of copper-bearing int rauterine devices (Cu-IUDs), corrosion behavior of copper in a simulated ut erine fluid was investigated in the presence of proteins. The proteins stud ied included serum albumin, gamma-globulin and hemoglobin. Electrochemical polarization resistance measurements indicated that, in all cases under stu dy, the corrosion rate of copper declined with time and the proteins always increased the rate. Moreover, different kinds of protein showed different dependence of copper corrosion rate on protein level. Addition of serum alb umin initially raised the copper corrosion rate; however, the higher albumi n concentration resulted in less promotion of the corrosion. X-ray diffract ion (XRD) of the specimen surface showed that, both in the presence and abs ence of serum albumin, cuprous oxide was the only corrosion product, even t hough at higher concentrations of albumin less cuprous oxide was formed. Th is implies that serum albumin does not alter the corrosion mechanism. Elect rochemical cathodic reduction of the oxide film and chemical analysis of so lution after corrosion testing proved that the proportion of soluble ionic copper in the whole corrosion products varied with the albumin level. The c opper corrosion rate in the presence of gamma-globulin or hemoglobin increa sed monotonically with increasing concentration of the protein. These three proteins shifted the corrosion potential of copper towards negative. It co uld be inferred that the proteins accelerated the anodic dissolution proces s of copper and hence enhanced its corrosion.