Electrodeposition from Molten Salt under Direct Magnetic Field Application

The effect of a direct magnetic field on the solid phase deposition of aluminum has been studied by using the molten salt of 2AlCl3-NaCl with addition of 5 mass% MnCl2. In the weak magnetic field range natural convection predominates the mass transfer rate of deposition and in the strong magnetic field range electromagnetic force controls the mass transfer rate and increases the critical current density to keep the deposition surface bright and smooth. Based on the boundary layer theory taking account of the electromagnetic force the analytical expression of the mass transfer rate has been derived. The theoretical result predicts the critical current density is proportional to one third power of the magnetic flux density and is confirmed by the experimental results.