Stochastic theory of pitting corrosion
Statistical variation of pitting potential and induction time for pit generation has been studied based on a stochastic theory which had been developed for the fracture of solid materials caused by applied stress. In order to obtain a large number of data, a multichannel pitting corrosion testing apparatus was developed, which can measure the pitting potential, or the induction time for 12 specimens in 1 experiment using 1 potentiostat. Analysis of experimental data for Type 304 stainless steel in 3.5 percent NaCl solution clarifies that the pitting process at a constant potential consists of 3 successive processes, each of which has a different pit generation rate depending on the potential and time. Only the first process is detected by the pitting potential determined by the potential sweep method. Experiment proves the prediction given by the theory that the pitting potential increases with the square root of the potential sweep velocity. Linear dependence of the pit generation rate on the potential suggests that the pitting process is controlled not by an electrochemical reaction, but by an electromechanical breakdown of the passive film.
- Research Organization:
- Hokkaido Univ., Sapporo
- OSTI ID:
- 7091971
- Journal Information:
- Corrosion; (United States), Journal Name: Corrosion; (United States) Vol. 33:7; ISSN CORRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360105* -- Metals & Alloys-- Corrosion & Erosion
ALKALI METAL COMPOUNDS
ALLOYS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION
CORROSION RESISTANT ALLOYS
CORROSIVE EFFECTS
HALIDES
HALOGEN COMPOUNDS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MATHEMATICAL MODELS
NICKEL ALLOYS
PITTING CORROSION
SODIUM CHLORIDES
SODIUM COMPOUNDS
STAINLESS STEEL-304
STAINLESS STEELS
STEELS
STOCHASTIC PROCESSES