The Effect of Nitrate on Salt Layers in Pitting Corrosion of 304L Stainless Steel

摘要: Current oscillations were observed during one-dimensional pitting corrosion of 304 L stainless steel in neutral 1 M NaCl solutions with varying NaNO3 concentrations. Synchrotron X-ray diffraction was used to identify the salt layer at front. It found that, although current induced higher concentrations NaNO3, species pit did not change and a nitrate-free present all solutions. At concentrations, crystal morphology detected. Electrochemical seen coincide secondary on surface indicating that two regimes operating parallel. radiography artificial pits measure front material loss situ. Before nitrate added, showed non-uniform across interface when beneath layer. Nitrate addition local region passivation propagated surface. Surface roughness quantified using R-values vary without clear trend until passivation, after which it stayed constant. A mechanism is suggested partial occurs these systems, where passivated areas are undercut as moves, generating surges current. © The Author(s) 2015. Published by ECS. This an open access article distributed under terms Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), permits unrestricted reuse work any