The effect of the magnetic field on the corrosion behavior of Nd-Fe-B permanent magnets

The effect of magnetic field on the corrosion behavior of an Nd-Fe-B magnet has been investigated in a naturally aerated 3.5 wt% sodium chloride solution. Experimentally, the study was carried out by weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization tests. The results have shown an evident effect of the magnetization state on the corrosion behavior of the Nd-Fe-B specimens. Magnetized specimens exhibited larger weight losses than non-magnetized ones. The difference in the specimens' corrosion rates were ascribed to the effect of the magnetic field on the transport of oxygen in the solution to the magnet/electrolyte interface, evidenced in the high-frequency response of the impedance diagrams, and to the adherence of particles to the magnetized specimens' surface due to magnetic field. Attempts have been made to explain the corrosion behavior observed for magnetized and non-magnetized sintered magnets