Effect of reduced graphene oxide addition on corrosion resistance and magnetic properties of sintered NdFeB magnets

Abstract

Neodymium–Iron–Boron (NdFeB) permanent magnets are indispensable in energy technologies such as wind turbines, electric vehicles, and robotics, but their processing is hindered by spontaneous powder ignition and severe corrosion susceptibility. Here, we demonstrate that incorporating 0.02 wt% reduced graphene oxide (rGO) during mechanical milling enables safe powder handling in ambient conditions without inert atmospheres, while simultaneously enhancing functional performance. Milling time was found to be critical: at 30 min, sintered magnets achieved remanence of 1.11 T, coercivity of 794 kA·m⁻¹, and a maximum energy product of 242 kJ·m⁻³, values comparable to commercial N35 magnets without heavy rare-earth additions. Electrochemical impedance spectroscopy revealed corrosion resistance up to two orders of magnitude higher than values typically reported for coated NdFeB magnets. Structural, electrochemical, and depth-profiling analyses confirmed that rGO acts as both a solid lubricant and encapsulating barrier, balancing grain refinement, oxidation suppression, and interfacial stabilization. This work establishes rGO-assisted processing as a scalable, sustainable, and cost-effective pathway to high-performance NdFeB magnets for next-generation energy conversion and storage systems.