Big Area Additive Manufacturing of High Performance Bonded NdFeB Magnets

Abstract

Additive manufacturing allows for the production of complex parts with minimum material waste, offering an effective technique for fabricating permanent magnets which frequently involve critical rare earth elements. In this report, we demonstrate a novel method - Big Area Additive Manufacturing (BAAM) - to fabricate isotropic near-net-shape NdFeB bonded magnets with magnetic and mechanical properties comparable or better than those of traditional injection molded magnets. The starting polymer magnet composite pellets consist of 65 vol% isotropic NdFeB powder and 35 vol% polyamide (Nylon-12). The density of the final BAAM magnet product reached 4.8 g/cm3, and the room temperature magnetic properties are: intrinsic coercivity Hci = 688.4 kA/m, remanence Br = 0.51 T, and energy product (BH)max = 43.49 kJ/m3 (5.47 MGOe). In addition, tensile tests performed on four dog-bone shaped specimens yielded an average ultimate tensile strength of 6.60 MPa and an average failure strain of 4.18%. Scanning electron microscopy images of the fracture surfaces indicate that the failure is primarily related to the debonding of the magnetic particles from the polymer binder. The present method significantly simplifies manufacturing of near-net-shape bonded magnets, enables efficient use of rare earth elements thus contributing towards enriching the supply of critical materials.

Recycled Sm-Co bonded magnet filaments for 3D printing of magnets

“…5,7 Additively manufactured magnets with 65 vol.% loading of magnet powder in binder are able to outperform injection molded magnets, even at this early stage of the technique. 4,7 In this paper, we describe the preparation of permanent magnet filaments intended for 3D printing using bonded Sm-Co powder reclaimed from swarfs in polylactic acid (PLA). PLA, a thermoplastic with a melting temperature of ∼178 • C, was selected as the binder for this investigation since its melting temperature is well below the Curie temperature of Sm-Co and due to its standard use in 3D printing.…”

Mechanochemically Processed Nd−Fe−Co−Cr−B Nanoparticles with High Coercivity and Reduced Spin Reorientation Transition Temperature

“…High performance permanent magnets are extensively used in electrical machines, electronics, aerospace, wind turbines, and electrical vehicle industries. Nd−Fe−B permanent magnets possess the highest energy product at room temperature but the properties decline at elevated temperatures because of their low Curie temperature (∼585 K) . (Dy/Tb) 2 Fe 14 B compounds have a higher anisotropy field than Nd 2 Fe 14 B, hence, Dy/Tb has been used to replace Nd in Nd−Fe−B alloys to increase service temperature.…”

Tensile strength properties of hybrid magnetic composite materials

“…In recent years, high demand for miniaturization of IT products, such as smart phones and tablets, makes Nd-Fe-B bonded magnets very applicable component with great expanse of production [2]. As a very suitable magnetic material with superior magnetic properties, Nd-Fe-B bonded magnets become the focus of many research groups [3][4][5].…”