A potential controlled transient technique for corrosion studies

Abstract

A two-parameter (potential V0 and time constant τ potential controlled relaxation technique is described in this paper. The method consists in applying an exponentially increasing potential input V0(1-exp(−t/τ)) to the system under activation control and measuring the current-time response. The shape of the current-time transient changes in an interesting manner when τ is varied. A theoretical analysis of the transient has been carried out and it is shown that the method can be applied for the measurement of kinetic parameters of electrochemical reactions. The utility of the method for the measurement of polarisation resistance and double layer capacitance of corrosion systems is demonstrated in this paper. The method is applicable only to systems with slow electron transfer where mass transfer effects can be neglected. This, and the problem of eliminating noise in systems with low corrosion rate, are the two chief limitations of this technique.