Research on surface corrosion resistance of sintered NdFeB by rotating transverse magnetic field assisted EDM-milling

Abstract

Sintered NdFeB, owing to its outstanding magnetic properties, finds widespread applications in diverse fields. However, its susceptibility to corrosion limits its utility. To enhance its corrosion resistance, a rotating transverse magnetic field is incorporated into the electrical discharge machining milling (EDM-M) process. Comparative experiments are conducted on sintered NdFeB by EDM-M, fixed transverse magnetic field assisted EDM-M(FTMEDM-M), and rotating transverse magnetic field assisted EDM-M(RTMEDM-M). Results indicate that the RTMEDM-M process yields the least surface cracks, the least "caves", and the recast layer which is the most uniform and the most continuous. Its impedance value is the highest, self-corrosion potential is the largest, and self-corrosion current density is the lowest according to its electrochemical impedance spectroscopy (EIS). In addition, its mass loss per unit area is the least, with the latest and the weakest reaction of chemical corrosion of the workpiece surface.