Electrochemistry of CoCrMo implant in Hanks’ solution and Mott-Schottky probe of alloy’s passive films M. Metikoš-Huković # , J. Katić Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, P.O. Box 177, 10000 Zagreb, Croatia Z. Grubač, I. Škugor Rončević Department of General and Inorganic Chemistry, Faculty of Chemistry and Technology, University of Split, R. Boskovica 35, 21000 Split, Croatia Abstract CoCrMo alloy has become one of the most important load–bearing materials in orthopedics. The influence of alloying components on the alloy’s electrochemical behavior: passivity, pitting corrosion and transpassivity has been investigated in situ under in vitro conditions in a Hanks’ solution. It was shown that anodic oxidation provides specific alloy’s surface functionalization that imparts high corrosion resistance to the alloy, thus determining material’s biocompatibility and implantation applicability. The deep understanding of the electronic (semiconducting) properties of passive films anodically formed on CoCrMo alloy is needed to predict long–term corrosion resistance of implant materials in simulated body fluids. Mott–Schottky tests were used to probe electronic properties of the passive films formed on the alloy and pure chromium (due to the “chromium like” alloys passivity). Both films were found to behave as p–type semiconductors, exhibiting the same flat band potential, E FB and the acceptor density values, N A corrected for the frequency dispersion. One order of magnitude lower N A for the alloy, which corresponds to the point defects and/or film’s nonstoichiometry, was explained by interaction of cation