Diffusivity of Point Defects in the Passive Film on Stainless Steel

Abstract

The semiconductor properties of passive films formed on AISI 316 stainless steel in sulfuric acid solution were studied by employing Mott-Schottky analysis in conjunction with the point defect model. The donor density of the passive films, which can be estimated by the Mott-Schottky plots, changes depending on the film formation potentials. Based on the Mott-Schottky analysis, an exponential relationship between donor density and the film formation potentials of the passive films was developed. The results showed that the donor densities evaluated from Mott-Schottky plots are in the range 2-3 × 10 21 cm −3 and decreased with the film formation potential. By assuming that the donors are oxygen ion vacancies and/or cation interstitials, the diffusion coefficient of the donors, (D O ), is calculated to be approximately 3.12 × 10 −16 cm 2 /s.

Electrochemical Studies on the Corrosion Behaviour of Laser Alloyed Zn-Sn Coatings on UNS G10150 Steel in 1M HCl Solution

“…This is seen in the reduction of polarization resistances of the B 1 sample from R p (75133 .cm 2 ) to R p (72598 .cm 2 ) at scanning speeds of 0.6 m/min and 0.8 m/min respectively. This agrees well with established studies to the effect that passive film structure is dynamic [41]. With regard to the effect of chloride ion, its aggressiveness stems from it being a relatively small anion which confers on it a rather high diffusivity.…”

Tree branch-shaped cupric oxide for highly effective photoelectrochemical water reduction

“…The Cu + sites become centres for charge recombination by trapping photogenerated holes, and thus inhibit charge transfer in CuO instead of promoting it. 31,32 On the other hand, Cu + defects are removed by further oxidation during the HMA treatment to produce an impurity free-CuO phase.…”

Bulk Diffusion of Cl through O Vacancies in α-Cr2O3: A Density Functional Theory Study

“…34,35 The hypothesis for Cl diffusion through oxygen vacancies is based on the presence of oxygen vacancies in the passive film during the passivation process at the metal/film z E-mail: liney.arnadottir@oregonstate.edu interface. 21,36 Oxygen vacancies also dominate the point defects that remain on the surface and in the bulk of the passive film after passivation and are possible pathways for Cl diffusion in the bulk. 37 Several DFT investigations have focused on bulk diffusion of O in oxides to predict their activation energies for diffusion and the most favorable diffusion pathways.…”