2022 Volume 34 Issue 3 Pages 53-58
Hydroxyapatite (HAp) prepared from baked livestock bone as fine solid powder efficiently inhibited the release of iron ions from the metallic iron plate in a 3% sodium chloride solution. The effects of fine powder HAp on Tafel measurement and anodic polarization using iron electrodes were examined. The response current density in the active region significantly increased depending on the potential on the iron electrode surface without HAp. On the other hand, on the iron electrode surface installed with fine powder HAp, the response current density increased in the active range up to about -0.2 V, and then, the increase in response current density was completely suppressed up to about 0.5V. Next, the surface of the iron electrode contacted with the fine powder HAp after the anodic polarization measurement was analyzed by TEM. As a result, the formation of iron hydroxide layer mainly containing Fe(OH)3 with a thickness of approximately 1.3 μm between the iron electrode and HAp was confirmed. It was suggested that fine powder HAp strongly suppressed the release of iron ions and electrons with protection of the passivation iron hydroxide layer.
