Study on the passivation properties of austenitic stainless steel 316LN based on the point defect model.

The Point Defect Model was successfully developed to study the passivation of 316LN. Steel's passive film exhibits n-type semi-conductivity with interstitial cations as the dominant point defect. The transfer coefficients α i and rate constants k i are independent of the applied potential but vary with temperature. The electronic structure of the barrier layer (bl) is discussed as a degenerate defect semiconductor in which the bl comprises essentially the depletion zone with the electronic charge and the electron-hole charge being concentrated at the metal/bl and the bl/solution interfaces, respectively. The closest classical analog is postulated to be a tunnel diode. • The Point defect model (PDM) is successfully applied to studying the passivation of 316LN in synthetic seawater. • The dominant point defect within the passive film of 316LN is the interstitial cation. • The rate constants of defect reactions for 316LN are independent of the applied potential. • The near-normal distribution of breakdown potential of 316LN is consistent with the PDM calculation. [ABSTRACT FROM AUTHOR]