Polarization behavior of bulk Zr-base amorphous alloy immersed in cell culture medium

Effects of amino acids and proteins on polarization behavior of Zr-base amorphous alloy were examined using Hanks' solution, minimum essential medium (MEM), and cell culture medium (MEM+FBS) consisting with MEM and fetal bovine serum (FBS), respectively. Amorphous powder consolidated Zr₅₅Al₁₀Ni₁₀Cu₁₅ alloy was cathodically and anodically polarized at the beginning of (after 1.8 ks) immersion and after a long-term (605 ks) immersion in each solution. Parameters on the anodic polarization curve; open-circuit potential (E_open), polarization resistance (R_p), and pitting potential (E_pit), were obtained for the examination of corrosion resistance. In the presence of amino acids and proteins, R_p and E_pit increased, indicating that resistance to both general and pitting corrosion was raised with those biomolecules. Thus, the adsorbed biomolecules probably work as a diffusion barrier to molecules and ions such as dissolved oxygen and phosphate and chloride ions. During immersion, the surface oxide film grew, leading to the increase in E_open, average E_pit, and R_p although the parameters showed wide variance of deviation probably caused by the defects in alloy structure. The lowest values of E_pit after the long-time immersion were not lower than those at the beginning of immersion, indicating that the sensitivity of defects to chloride ion was not enhanced during immersion. However, the pitting corrosion resistance decreased during immersion because the potential difference between E_open and E_pit decreased.