Convective corrosion pattern of steel in water under gradient magnetic fields

摘要

Recently, observations have been reported of the corrosion pattern of a steel plate in the presence of a magnetic field with a field gradient. The steel plate was placed vertically in an open vessel filled with purified water. When the magnetic field was applied normal to the center of the plate while keeping the temperature of water constant, a corrosion pattern was observed where a pair of vortices emerges bilaterally in the center of the plate. Here we present a theory that explains the emergence of this convective pattern: The non-equilibrium-concentration gradient of oxygen in water is created and maintained by the corrosion and the supply of oxygen from the surroundings. As a result, it drives a convective flow of water due to the magnetic buoyancy force on the water. Predictions made are consistent with observations done so far. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 6]