Utilization of the potentiostatic pulse method in the study of corrosion processes

Abstract

INTRODUCTION POTEN~OSTATIC polarization measurements have been extensively utilized in the past decade, in studies of metallic corrosion in electrolyte solutions. This method is divided into two general classes: potential step and potential sweep. In the potential step method, electrode potential is rapidly changed over a finite increment, and current measured after a definite time interval, when the metallic surface reaches a steady state. In the potential sweep (or potentiodynamic) method the electrode potential is continuously changed at a constant rate and the current is recorded simultaneously. Potentiostatic pulse methods derive from the potential step method. In the potentiostatic pulse (or potential step pulse) method the potential is changed over a finite increment, and the transient of the current is recorded over a definite time interval. This method is not so widely utilized in corrosion studies. However, this method is a very common technique in the electrode reaction and adsorption studies. This paper reports the use of a potential step method, in which the number of coulombs passed following application of a potential step is measured as a function of time, for the study of corrosion resistance of Al-Zn and of titanium alloys in alkaline solutions and in presence of halide ions.