A Method for Determining the Corrosion Rate of a Metal under a Thin Electrolyte Film

Abstract

Electrochemical impedance spectroscopy (EIS) was applied to evaluate corrosion rates of steels covered with a thin electrolyte film. A two-electrode cell consisting of a pair of identical steel plates embedded in epoxy resin was used for the EIS measurements under the thin electrolyte film. A transmission line type equivalent circuit was employed to describe the EIS behavior. Using this method, a charge transfer resistance was successfully estimated under uneven current distributions. This technique was applied to estimate the corrosion rates of steels under electrolyte film thickness in a range of 5 μm to 1 mm.

Simultaneous Measurements of Polarization Resistance and Hydrogen Permeation Current of Iron in an Aqueous NaCl Droplet

“…In the last stage of the drying, the i corr of Fe should increase due to enhancement of the ORR, 35,36) although our system could not measure the value of R p just before the NaCl droplet dried up completely. This mechanism explains why the E corr increases to a higher value in the last stage of drying, as shown in Fig.…”

“…This suggests that the corrosion reaction proceeded under a diffusion-controlled condition of the ORR, since the electrolyte layer thickness was thicker than the convection layer. 35,36) In this case, the i corr of Fe can be estimated from the limiting current density of the ORR on the Fe. The value of i corr estimated in this study (ca.…”

Observation of Pit Initiation and Growth of Stainless Steel under a Chloride Solution Droplet —Effect of S Content on Pit Initiation, Growth, and Repassivation—

“…On the other hand, our group successfully measured the corrosion rate of iron (Fe) and zinc (Zn) for various droplet thicknesses using electrochemical impedance spectroscopy (EIS); the results showed that the corrosion rates of Fe and Zn depend on the droplet thickness. 19,20) Furthermore, in addition to general corrosion metal (Fe and Zn), EIS was applied to localized corrosion metal (SS), which was exposed to a marine atmospheric environment, the pit initiation was monitored. 21) The surface condition and corrosion rate of SS were continuously measured using impedance at 10 kHz and 10 mHz, respectively.…”

Effect of Environmental Factors on Hydrogen Absorption into Steel Sheet under a Wet-dry Cyclic Corrosion Condition

“…Generally, as the electrolyte film thickness becomes larger than several 10 μm, the corrosion rate of steel decreases. 32) This is because oxygen reduction reaction rate decreases with increasing the electrolyte film thickness. Additionally, the corrosion potential of steel shifts in the less noble direction with increasing the electrolyte film thickness.…”