Analysis of the Wear-Assisted Corrosion of a Super-Duplex Stainless-Steel Using an Interface Film Growth Model

Abstract

The wear-assisted corrosion response of a super-duplex stainless-steel alloy from a single asperity contact was measured using the contact mode of an atomic force microscope (AFM). The AFM tip, as illustrated in the figure below, applied increasing loads to an isolated surface region that was polarized to two different static potentials in a 0.6 M NaCl solution. The AFM tip was swept across the isolated, exposed, surface region of the alloy while the alloy response was measured by a potentiostat. The wear-assisted corrosion response was modeled using an interfacial film growth model (IFM) that was used to estimate kinetics parameters for the response of the alloy as a function of the applied loads and polarization potentials.The average response values from the IFM were then approximated using an Arrhenius expression that incorporated the peak applied stress and activation volume for the reaction as modifiers to the energy barrier for oxide film formation. This Arrhenius model suggested that the stress fields from the single asperity contact induced damage in the protective oxide and also disrupted other oxide-formation processes at the oxide-electrolyte interface. The induced damage and the disruption of the oxide-formation processes, as a function of the applied stress, slowed repassivation and allowed increasingly high corrosion currents as the stress fields increased.AcknowledgmentsThe U.S. Naval Research Laboratory sponsored this work under work unit 1E19 as part of its Basic Research Program. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Office of Naval Research, the U.S. Navy, the Department of Defense, or the U.S. government.Figure CaptionSchematic diagram of experimental setup of the AFM tip loading the isolated region on the super-duplex stainless-steel alloy surface while the potentiostat is used to both polarize the alloy and measure its response to the load. Figure 1