Majority of High Performance NdFeB Magnet

High performance NdFeB Magnet is a permanent magnet made of NdFeB and other rare earth elements (REEs). It has a wide variety of applications including electric vehicles (EV), wind turbines, medical devices and more. It is also used in magnetic resonance imaging (MRI) and in advanced communications equipment. Due to its unique properties, such as high magnetic energy product, high Curie temperature, low coercitivity and high magnetic anisotropy, it is a sought after material for many applications.

Despite its dominance in production, China has struggled to move up the value chain and export its magnets into Western markets, with most advanced sintered NdFeB magnets still being manufactured by Japan’s Sumitomo Special Metals and Hitachi Metals. The reason is that mid-stream manufacturing of NdFeB magnets requires significant capital, which not all companies can afford to invest.

This may explain why Beijing restricts the vast majority of its domestic NdFeB magnet production. Rather than selling a substantial fraction of its output overseas, it has invested the bulk of its production into addressing Chinese domestic demand for EVs and wind power.

Assuming no technological breakthrough, projected demand for high-performance NdFeB magnets from EVs and wind will likely outstrip supply by 2025. Given that Beijing is unlikely to export a significant portion of its own burgeoning production to the West, the resulting shortage may have a pronounced impact on clean energy deployment, especially in countries like the United States and Germany, which use NdFeB magnets in their EV and wind power production plants.

Various metallurgical processes at different technology-readiness levels have been developed to recover REEs from NdFeB magnet scrap, such as hydrogen decrepitation, chemical vapor transport, liquid metal extraction and pyrometallurgical slag extraction. However, these methods have all been developed to deal with pre-consumer NdFeB magnet scrap that is relatively clean and homogenous. Recovering REEs from complex post-consumer NdFeB scrap, such as shredded magnet waste, is more challenging and has yet to be achieved in practice.

NdFeB bonded magnets are typically produced by extruding a mixture of NdFeB powder and a polymer such as polyphenylene-sulfide (PPS) or polyamide (Nylon). While PPS binders offer better mechanical properties, Nylon offers superior thermal resistance and corrosion protection.

The current study investigates the possibility of producing NdFeB bonded magnets using a hybrid system of an extruder that combines PPS with a BAAM machine. The results show that the new fabricated bonded magnets exhibit better magnetic, mechanical and microstructural properties than traditional injection molded commercial products.

The improvement in the tensile stress-strain curve of the fabricated bonded magnets is attributed to an improved microstructure of the NdFeB-Nylon composite and its effective distribution. The results also suggest that the new fabricated bonded magnets could be used to replace traditional injection molded NdFeB magnets in a wide range of end-use applications. Lastly, the ability of the BAAM fabricated bonded magnets to operate in harsh conditions without degradation of their magnetic and mechanical properties is highlighted. This capability demonstrates the potential of the proposed hybrid system for developing advanced magnets for industrial use.