Effect of Magnetic Field on Anodic Current of Iron in Phosphoric Acid Solution at Various Potentials

The effects of magnetic field on the anodic current of iron in 0.5 mol/L H₃PO₄ solution at different potentials were studied by using polarization curve and potentiostatic polarization method. The results showed that the anodic polarization curve under 0 T magnetic field showed typical characteristics of anodic dissolution, dissolution-passivation transition, steady-state passivation and overpassivation. The range of active dissolution zone of anodic polarization curve expanded under 0.4 T magnetic field, so that there was no passivation zone. The surface of iron electrode was relatively uniform after polarization under 0 T magnetic field. While under the 0.4 T magnetic field, the iron electrode underwent accelerated dissolved after polarization, and local depressions appearred on both sides of its horizontal direction. When the mass transfer process of the product film on the iron electrode surface to the solution in 1.2-1.5 V high potential range was the anodic reaction rate control step, applying magnetic field increased anodic current density significantly, and also accelerated local dissolution of iron electrode. The effect of applying or withdrawing magnetic field on oxygen evolution reaction was not obvious.