Formation characteristics of calcium phosphate deposits on a metal surface by H2O2-electrolysis reaction under various conditions

Kazuaki Kanamoto, Koreyoshi Imamura, Nobuhide Kataoka, Jun Oshitani, Hiroyuki Imanaka, Kazuhiro Nakanishi

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The cathodic electrolysis of H2O2 (H2O2 + e- → OH- + {radical dot}OH) on a metal surface in the presence of calcium and phosphate ions results in the formation of calcium phosphate deposits on the metal surface. In this study, the deposits formed under various treatment conditions (pHs, concentrations and ratios of calcium/phosphate ions, and so on) were characterized by scanning electron spectroscopy (SEM), and X-ray diffractometry. The exclusive formation of hydroxyapatite, HAP, was observed under comparatively narrow conditions (pH 3-4, [Ca+]/[PO43-] = 25 mM/15 mM), which is clearly different from the reported conditions for the deposition of HAP on titanium substrates. HAP was deposited in the form of a layer, comprised of morphologically amorphous HAP flakes that were less than 20 nm thick. SEM and FTIR analyses of the deposit at different stages of H2O2-electrolysis revealed that a few dozen nanometer-sized spheres of amorphous calcium phosphate were formed in the first step and then fused with each other to form ribbon-like flakes of HAP or broken glass-like brushite, depending on the pH. The pH for HAP formation on a stainless steel surface was markedly lower than that used for titanium, and the observed process by which amorphous calcium phosphate is converted to HAP was markedly different from that for the electrochemical deposition (electrolysis of water) of HAP on a titanium substrate.

Original languageEnglish
Pages (from-to)79-86
Number of pages8
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume350
Issue number1-3
DOIs
Publication statusPublished - Oct 20 2009

Keywords

  • Amorphous
  • Calcium phosphate
  • Cathodic electrolysis
  • Hydrogen peroxide
  • Hydroxyapatite
  • Stainless steel

ASJC Scopus subject areas

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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