On the Origin of the Second Anodic Peak During the Polarization of Stainless Steel in Sulfuric Acid

Abstract

The origins of the second anodic current peak in polarization curves of AISI 430 (UNS S43000) stainless steel in deaerated 0.1 M sulfuric acid (H2SO4) have been investigated by potentiodynamic polarization and atomic emission spectroelectrochemistry (AESEC). The elemental dissolution rates of Fe, Cr, Ni, Cu, and Mn were measured in real time during linear potential sweep voltammetry, revealing the formation and dissolution of a copper-rich corrosion product layer. The deposition and subsequent dissolution of this copper layer is proposed to be the main cause of the second anodic current peak. The negative current loop observed after the first anodic peak is attributed to the cathodic reduction of H+ ion on the copper-enriched layer. Other factors such as the oxidation of the adsorbed H atoms on the copper-enriched layer and the presence of chromium-impoverished grain boundaries are shown to have a negligible effect on the second anodic current peak.

Dealloying of Al2Cu, Al7Cu2Fe, and Al2CuMg intermetallic phases to form nanoparticulate copper films

“…During this stage, the selective dissolution of Al leaves behind a residual copper film on the surface. Previous studies have demonstrated that for Al 2 Cu, this film is nearly uniform and it is reasonable to assume that it contributes to the decreasing dissolution rate beyond a1, as has been observed for residual copper films on stainless steel . It is clear that the a2 maximum corresponds to the onset of copper dissolution, j Cu , as a sharp peak, while j Al shows a short plateau on the decreasing edge of the passivation peak.…”

Dissolution and Passivation of a Silicon-Rich Austenitic Stainless Steel during Active-Passive Cycles in Sulfuric and Nitric Acid

“…36,43 X1CrNiSi18-15-4 SS presents a high concentration of Si and Cr while X2CrNiN18-10 SS surface is mainly enriched in Cr. Main differences in the chemical structure of the oxide layer concern Cr and Si.…”

“…It is however not the case in pure HNO 3 , where the X1CrNiSi18-15-4 SS dissolves more rapidly than the X2CrNiN18-10 SS, and this is probably due to the properties of the particular passive layer of the X1CrNiSi18-15-4 SS. This film is composed of a silicon rich oxide, very likely chromium silicate whose stoichiometry and thickness have not been clearly determined, 36 nor observed in situ over the very first seconds of formation. A first attempt of characterization of this oxide layer was made in previous work, 25 through the measurement of the activation potential, which should be directly related to E…”

Atomic Emission Spectroelectrochemistry: Real-Time Rate Measurements of Dissolution, Corrosion, and Passivation

“…76 A typical example of a Type 304 austenitic stainless steel (UNS S30400) in 2 M H 2 SO 4 is shown in Figure 14, redrawn after Ogle, et al 77 Note that the j e vs. E characteristic curve shows two E j = 0 points, defining two cathodic and two anodic domains. The second cathodic domain is referred to as a "cathodic loop," [78][79][80][81] the origin of which has been debated.…”