Effects of dissolved Ca2+ and Mg2+ on passivity of UNS N08800 alloy in simulated crevice chemistries with and without Pb contamination at 300 °C

The effects of Ca2+ and Mg2+ on passivity of UNS N08800 alloy at 300 °C are experimentally investigated in simulated crevice chemistries. In the Pb-free solutions, the impacts of Ca2+ and/or Mg2+ are similarly detrimental, but less in extent, as those caused by Pb-contamination, as indicated by the increased passive current density, the lower breakdown potential, the promoted incorporation of hydrogen into the passive films and the formation of the films with highly defective structures containing more MOH bonds. However, when Ca2+ and/or Mg2+ are/is concurrently present with Pb cation, they mitigate the detrimental impact of lead on the passivity.