Fabrication and Characterization of Fe₁₆N₂Micro‐Flake Powders and Their Extrusion‐Based 3D Printing into Permanent Magnet Form

Abstract

Fe16N2 is a compound with giant saturation magnetization approaching or exceeding that of rare‐earth‐based permanent magnets. The abundance of its elements and low‐cost synthesis of this compound has made it highly attractive to replace rare‐earth‐based permanent magnets that are becoming ever more expensive to utilize in applications. Herein, its synthesis from Fe flakes by surfactant‐assisted high energy ball milling is demonstrated. The synthesized Fe flakes are then reduced under forming gas (Ar/H2), followed by nitridation at low temperatures under ammonia (NH3) gas. The formation of Fe16N2 phase exceeding 50% by volumetric fraction is observed and confirmed by X‐ray diffraction and Mössbauer analysis. Following the Fe16N2 flake synthesis, extrusion‐based 3D printing is used to check the feasibility of incorporation of the flakes into functional polymer matrix composites. For this purpose, an ink of intermixed synthesized powder with photoresist SU8 is used. Using the prescribed method, a prototype Fe16N2 permanent magnet composite is successfully produced using an additive manufacturing approach. Such efficient production of Fe16N2 powders via routes already applicable to magnet production and the consolidation of the powders with 3D printing are expected to open up new possibilities for next‐generation permanent magnet applications.

3D Printing Technologies for Fabrication of Magnetic Materials Based on Metal–Polymer Composites: A Review

“…Here, several main groups of powders that are used in FDM technology can be distinguished. They are spherical powders with a particle size of about 30-50 µm, obtained mainly by gas atomization [30,60,61,68]; powders with irregular, flaked, or fragmented shaped particles with the longest dimension from several microns to several millimeters obtained by mechanical grinding in ball mills [77] or by melt spinning [78,79]; and micron and nanosized particles of various shapes obtained by chemical methods [76]. The spherical shape and fine size usually promote decreased viscosity.…”

“…In [77], the preparation of a composite based on Fe 16 N 2 flake powder in a photopolymer matrix was studied. Fe 16 N 2 is a compound with a giant saturation magnetization that is close to or exceeding that of rare earth permanent magnets.…”

“…The synthesis of the compound can be carried out by nitriding pure iron particles in an ammonia atmosphere. In [77], when printing using the DIW method, an external magnetic field of 0.7 T was applied. As a result, the composite had the following properties: H c = 350 Oe, M s = 106 emu/g with a filler content of 50 wt.%.…”

Innovative technique for patterning Nd–Fe–B arrays and development of a microfluidic device with high trapping efficiency

“…The mixture was ball milled at 700 rpm for 12 h. As-prepared micro-flakes were cleaned from byproducts; the powder was sonicated in ethanol followed by centrifugation and removal of the supernatant. Cleaned flakes were stored in hexane and dried before mixing with PDMS [68] (scheme 1). PDMS belongs to a group of polymeric silicones and is optically clear, non-toxic, and non-flammable [69,70].…”

Ternary Multifunctional Composites with Magnetorheological Actuation and Piezoresistive Sensing Response

“…Magnetoactive composites are capable of sensing and acting when subjected to an external magnetic field, − enabling less intrusive remote actuations and making them compatible with IoT related applications. Such characteristics have led magnetoactive materials to be applied in areas including printed electronics, , shape memory composites, permanent magnets, and magnetic sensors and actuators …”