Oxygen Reduction on Stainless Steel in Concentrated Chloride Media

Abstract

In this work, a rotating disk electrode was used to measure the cathodic kinetics on stainless steel as a function of diffusion layer thickness (6 to 60 μm) and chloride concentration (0.6 to 5.3 M NaCl). It was found that, while the cathodic kinetics followed the Levich equation for large diffusion layer thicknesses, the Levich equation overpredicts the mass-transfer limited current density for diffusion layer thicknesses less than 20 μm. Also, an unusual transitory response between the activation and mass-transfer controlled regions was observed for small diffusion layer thicknesses that was more apparent in lower concentration solutions. The presence and reduction of an oxide film and a transition in the oxygen reduction mechanism were identified as possible reasons for this response. The implications of these results on atmospheric corrosion kinetics under thin electrolyte layers is discussed.

Erosion–Corrosion of AISI 304L Stainless Steel Affected by Industrial Copper Tailings

“…Concerning the variational patterns of |b O2 | values, while higher values were observed for the filtrate solution (≡242 mV/dec) in comparison with the NaCl solution (≡146 mV/dec), there was no significant changes with the rotation rates. These |b O2 | values for the NaCl solution were similar to those reported in literature for stainless steel samples, which ranged between 140 mV/dec [37][38][39]. The ORR kinetics showed an uneven i 0,O2 change with rotation rate (Table 1) characterized by lower and higher i 0,O2 values at higher rotation rates for the NaCl and filtrate solution, respectively.…”

Stress-Affected Oxygen Reduction Reaction Rates on UNS S13800 Stainless Steel

“…ORR in this potential window is considered to proceed at rates faster than transport occurs, which should not be influenced by sample stress. However, previous efforts have demonstrated hysteresis in cyclic polarization experiments with discernible current difference between −0.6 and −0.8 V SCE that were attributed to oxide reduction during the tail end of the cathodic sweep ( Alexander et al, 2018 ).…”

“…ORR on stainless steels and iron is generally recognized as proceeding with adsorption of molecular oxygen onto the surface followed by reduction steps and product dissociation ( Jovancicevic and Bockris, 1986 ; Calvo and Schiffrin, 1988 ; Ng et al, 2020 ). ORR on oxide covered stainless steels in chloride electrolytes has been shown to follow the four electron pathway as well as a mix of two and four electron pathways ( Le Bozec et al, 2001 ; Alexander et al, 2018 ). Pre-reduced stainless steels were shown to follow the four electron pathway, while polished and passivated surfaces include a mix of 2 and 4 electron pathways.…”

“…Pre-reduced stainless steels were shown to follow the four electron pathway, while polished and passivated surfaces include a mix of 2 and 4 electron pathways. Recent work has also shown that transport limitations can impact reaction pathway, shifting from the four-electron pathway to mixed response as the diffusion layer decreases ( Alexander et al, 2018 ). These reaction pathways imply a shift in adsorbed species as well as their reactivity.…”

“…They range from amorphous to polycrystalline; typically falling within a nanocrystalline regime over alloy grains and have less order over intergranular regions ( Maurice and Marcus, 2018 ). As a result, stress has multiple mechanistic routes to impact corrosion reaction kinetics ( Chen et al, 2008 ; Thébault et al, 2011 ; Wang et al, 2014 ; Van den Steen et al, 2016 ; Hangarter C. and Policastro S. A., 2017 ; Hangarter C. M. and Policastro S. A., 2017 ; Liu et al, 2017 ; Palani et al, 2017 ; Alexander et al, 2018 ). Strain on pristine semiconductors induces density of states shifts that have been shown to impact charge carrier mobility ( Sun et al, 2007 ).…”