Acceleration or retardation by a magnetic field of the anodic processes of iron in molybdate-bearing chloride solutions

Abstract

The modulation by a horizontal magnetic field of the anodic processes of iron in molybdate-bearing chloride solutions is determined. The magnetic field can accelerate or retard the anodic reaction depending on the rate-controlling steps at specified electrode potentials. The anodic current density arising from uniform dissolution from open or semi-open pits is increased by the magnetic field. The current density originating from occluded pits can be decreased by the magnetic field, where autocatalysis has a dominant effect on the pitting rate. The effect of the magnetic field on the pitting corrosion is a combination of the influence on electrochemical reactions at the interfaces of the pits and the disturbance of the autocatalysis process inside the pit enclave through the magnetohydrodynamic (MHD) effect. Micro-MHD effects for specific locations and macro-MHD effects for pitting systems are recommended to illustrate the magnetic effect on localized corrosion phenomena at various combinations of potentials and solution compositions.