TRANSIENT CURRENT RESPONSE OF IRON-NICKEL-CHROMIUM ALLOY ROTATING CYLINDRICAL ELECTRODES SCRIBED WITH A DROPPED STYLUS

The scribing technique was used to investigate dissolution and repassi vation kinetics of three iron-nickel-chromium (Fe-Ni-Cr) electrodes im mersed in a 0.01 M potassium chloride (KCl) + 0.01 M sulfuric acid (H2 SO4) electrolyte. The study related the extent of surface deformation with the electrochemical response, as a result of a Vickers diamond im pacting a rotating cylindrical electrode (RCE). The transient current response and transient impact force (F-imp) of the stylus were measure d simultaneously. For a given alloy, the scratch current density (i(s) ) was observed to remain unchanged with respect to F-imp of the stylus from 44 N to 432 N. Activation charge density (q(act)) was observed t o remain constant with F-imp, whereas the repassivation charge density (q(rep)) increased with increasing F-imp. Surface deformation of the alloys was discussed according to the principles of microindentation o f alloys, which showed that electrochemical responses for the alloys c orresponded with the plastically deformed zone associated with the scr atch Alloy composition affected I-s q(act), and q(rep) for the F-imp v alues measured.