Theoretical prediction of the scan rate dependencies of the pitting potential and the probability distribution in the induction time
- Pennsylvania State Univ., University Park, PA (United States). Center for Advanced Materials
The point defect model (PDM) has been used to derive the dependence of the pitting potential on the voltage scan rate. Relationships derived from the PDM predict that the observed pitting potential is a linear function of the square root of voltage scan rate at low scan rates, which agrees with experimental data reported in the literature. Furthermore, the critical concentration of condensed cation vacancies that give rise to passivity breakdown, as estimated from the sweep rate dependence of the pitting potential, is found to be in good agreement with that estimated from structural considerations. The PDM is also used to predict the probability distribution function in the induction time for pitting (t{sub ind}), that is, the survival probability, by assuming that the maximum diffusivity of the cation vacancy in a population of specimens is log-normally distributed. This calculated external distribution in the induction time is found to be in reasonable agreement with experimental induction time data for passivity breakdown on multiple specimens of single crystal (100) Ni and polycrystalline nickel buffered chloride solutions.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-84ER45164
- OSTI ID:
- 511938
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 5; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Vacancy condensation as the precursor to passivity breakdown
Stochastic theory of pitting corrosion