hrvatski

Istraživanje biokompatibilnih modificiranih površina slitina u fiziološkoj otopini

CoCrMo alloy has been widely used as biomaterials to assist with the repair or replacement of bone tissue in the human's body. In this work the influence of alloying elements on the properties of passive films that have the main role in the alloy biocompatibility was studied. In vitro investigation was performed in the physiological-Hank's solution, pH 6.8. Electrochemical techniques were used to study oxido-reduction processes, while the structural properties of electrified interfaces and solid state processes (changes) inside the oxide films were studied by electrochemical impedance spectroscopy. The quantitative analysis of metallic ions produced during the prolonged immersion of the investigated materials in Hank's solution was carried out by coupled plasma mass spectrometry of high resolution (HR ICP-MS). The passivation of both CoCrMo alloy and pure metals take place spontaneously in Hank's solution. The oxide layer on the alloy has a duplex structure ; the inner layer is mainly Cr(III) oxide, and it plays a decisive role in corrosion stability of the alloy. Co(II) and Mo(IV) oxides are the main components of the outer part of the passive layer. The charge transfer occurs via cationic vacancies and electrons. The complexation of mobile cationic chromium vacancies with Mo(VI) species inside the inner layer is the main reason for an increased corrosion stability of alloy in comparison with the pure chromium. The corrosion stability of investigated materials determined by measuring the concentration of metallic ions during their prolong immersion in Hunk's solution agree well with the results obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The release of cobalt ions from the pure Co was much greater than that release from the alloy.

CoCrMo slitina; Pasivitet; Fiziološka otopina; Ciklička voltametrija; Impedancijska spektroskopija; Masena spektroskopija

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