Influence of Nd-base alloy addition on improving the characteristics of recycled sintered NdFeB permanent magnets

The continued miniaturization of electric motors, 3C appliances, wind turbines, and even defense uses has led to an increasing demand for high-performance Neodymium (NdFeB) permanent magnets. Growing concern over the supply risks of the rare earth elements (REEs) used in these magnets has prompted the development of a recycling program for these end-of-life magnet products. In this study, a new and valid recycling method for sintered NdFeB magnets is proposed. Recycled sintered NdFeB permanent magnets were prepared on a large scale of up to 100 kg per batch by adding Nd-base alloy to N48H grade NdFeB scrap magnets, and their magnetic properties and high-temperature aging characteristics were evaluated at the same time. The differences in magnetic properties, microstructure, resistance to high temperature and corrosion, mechanical strength, and impurity content inside the sintered magnets were further evaluated by BH Tracer measurements, XRD analysis, SEM analysis, temperature resistance analysis, Pressure Cooker Test (PCT) analysis, three-point bending test, and analysis of C/N/O content. The results show that the addition of Nd-Co-Ga alloy has the best magnetic properties, resulting in a recycled sintered magnet with a coercivity H-i(c) of 17.82 kOe, maximum magnetic energy (BH)(max) of 46.58 MGOe, a weight loss per unit area < 0.8 mg/cm(2), a three-point bend of 281.83 MPa. Indeed, produces magnets via the careful addition of a proprietary mix of blended elements that can almost achieve those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity sintered magnets suitable for offshore wind turbines and electric vehicle motors that operate at high temperatures for a long time and may be exposed to water.