Impedance Study of Ni-Cr Alloy in Contact with Biologics and Organic Solution using Constant Phase Element

Hilal N, Leguedani N and Ha

Abstract

The electrochemical characterization and the physical parameters of the Ni-Cr dental implant alloy were studiedin contact with two biological (artificial saliva and milk) and organic (vinegar) solutions at Open Circuit Potential(OCP) and at 37°C for one-hour time immersion. In this work we are focused to model the response function of thisbiomaterial using an Electrical Equivalent Circuit (EEC) to analyze data obtained by the Electrochemical ImpedanceSpectroscopy (EIS). The experimental results showed that the Ni-Cr alloy is a passive biomaterial which presents aquiet good resistance to corrosion. A model of electric circuit was proposed to describe the electrochemical behaviorof this biomaterial on the frequency range (0,100 KHz). The Bode diagram indicated the presence of at least onetime constant during the kinetic process. The nature of the film and the study of the morphology of the surface ofthe material are achieved with the present investigation. Other chemical measurements namely the SEM and EDXcan be undertaken to confirm our results. The theoretical form of the proposed response function involved ConstantPhase Elements (CPE) to explain the apparent heterogeneity on the interface Metal/film/Electrolyte. Theoreticalmodel predictions are in good agreement with the experimental data with a best-fit corresponding to a minimumstandard deviation (The Chi-square values χ2 is of 10-4).

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