Effect of chloride ion on the anodic polarization behavior of the Zr65Al7.5Ni10Cu17.5 amorphous alloy in phosphate buffered solution

The corrosion behavior of the Zr65Al7.5Ni10Cu17.5 amorphous alloy was investigated in a phosphate buffered saline solution and in phosphate-citric acid buffered solutions with various chloride-ion concentrations from 0 to 1.0 M, to examine the performance of the alloy as a biomaterial. The surface condition of the non-polarized and polarized alloy in the passive region was characterized using X-ray photoelectron spectroscopy. The susceptibility of this alloy to pitting corrosion was small at a small amount of chloride ion, but it increased with the chloride-ion concentration. Phosphate ion adsorbed on zirconium oxide in the surface raised the susceptibility to the pitting corrosion. On the other hand, phosphate ion is hardly adsorbed by aluminum oxide, so aluminum oxide in the surface diminished the susceptibility to the pitting corrosion. (C) 2000 Elsevier Science Ltd. All rights reserved.