Non Contacting Corrosion Technique: a New Method for the Polarization Resistance Measurement in Reinforcement

Polarization Resistance is now a routine technique well demonstrated to be able to measure the gravimetric loss due to corrosion in the majority of the electrolyte/ metal systems. Until now the determination of R_p has been made through using direct current or from the low frequency range when determining the electrochemical impedance. In order to measure metal corrosion it is necessary to make physical contact with the metallic piece which acts as working electrode. In present paper the feasibility of using a new method, Non Contacting Corrosion Technique, NCC, for polarizing the metal without the need of physical contact with it, is presented. The polarization is obtained through the induction of a current by means of an external electrical field. The model used for the calculation of the corrosion rate assumes that the current runs in parallel through the electrolyte and the metal and the current electrostatically polarizes the metal. The resistance to the electrostatic polarization is related to the faradaic reaction which has been verified by comparison to the gravimetric losses. This resistance has been called Inductive Polarization Resistance, R_pi, for the sake of equivalence to the traditional Polarization Resistance, R_{p.
Keywords: Corrosion, Induction, Non contacting method, Polarization Resistance.}