Développement et applications des biocéramiques

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

Abstract

Hilal N, Leguedani N and Hafid MM*

The electrochemical characterization and the physical parameters of the Ni-Cr dental implant alloy were studied
in 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 this
biomaterial using an Electrical Equivalent Circuit (EEC) to analyze data obtained by the Electrochemical Impedance
Spectroscopy (EIS). The experimental results showed that the Ni-Cr alloy is a passive biomaterial which presents a
quiet good resistance to corrosion. A model of electric circuit was proposed to describe the electrochemical behavior
of this biomaterial on the frequency range (0,100 KHz). The Bode diagram indicated the presence of at least one
time constant during the kinetic process. The nature of the film and the study of the morphology of the surface of
the material are achieved with the present investigation. Other chemical measurements namely the SEM and EDX
can be undertaken to confirm our results. The theoretical form of the proposed response function involved Constant
Phase Elements (CPE) to explain the apparent heterogeneity on the interface Metal/film/Electrolyte. Theoretical
model predictions are in good agreement with the experimental data with a best-fit corresponding to a minimum
standard deviation (The Chi-square values χ2 is of 10-4).