Anodic dissolution of 304 stainless steel using atomic emission spectroelectrochemistry

In this work a new spectroelectrochemical method based on an inductively coupled plasma atomic emission spectrometry has been developed and used to measure the elementary dissolution rates of Fe, Cr, Ni, Mn, Mo, and Cu simultaneously during linear scan voltammetry of a 304 stainless steel in the active region. Simultaneous dissolution was observed For all elements with the exception of copper. which appeared in solution at a potential approximately 100 mV more positive. The Tafel slopes for Fc, Cr, Ni, and Mn partial dissolution rates were measured around the corrosion potential and found to be identical within experimental error, between 59 and 68 mV/decade. The anodic dissolution of copper in acidic chloride and sulfate solutions was used to establish the quantitative relationship between the concentration transients and the dissolution rate. The residence time distribution of the electrochemical flow cell was determined using galvanostatic pulses of copper or stainless steel dissolution. The experimental residence time distribution could be approximated to a high degree of accuracy at both long and short times by a log-normal distribution. The effect of the residence time distribution on the shape of partial elemental current transients during linear scan voltammetry was investigated by numerical simulation. (C) 2000 The Electrochemical Society. S0013-4651(99)10-067-3. All rights reserved.