ELECTROCHEMICAL AND XPS STUDIES OF TITANIUM FOR BIOMATERIAL APPLICATIONS WITH RESPECT TO THE EFFECT OF HYDROGEN-PEROXIDE

Electrochemical measurements, x-ray photoelectron spectroscopy, and sc anning tunneling microscopy have been used to study the effect of hydr ogen peroxide on the passivity of titanium in a phosphate-buffered sal ine (PBS) solution. The results indicate that the passive film formed in the PBS solution-with and without addition of H2O2-may be described with a two-layer structure model. The inner layer has a structure clo se to TiO2 whereas the outer layer consists of hydroxylated compounds. The introduction of H2O2 in the PBS solution broadens the hydroxylate -rich region, probably due to the formation of a Ti(IV)-H(2)0(2) compl ex. Furthermore, the presence of H2O2 results in enhanced dissolution of titanium and a rougher surface on a microscopic scale. Finally, a d ark pigmentation (blue color) is observed when titanium has been expos ed-for several weeks-to PBS with additions of H2O2. (C) 1994 John Wile y and Sons, Inc.