Production of complex shape magnets using additive manufacturing: A state-of-the-art analysis

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705719886894 ◽

2019 ◽

pp. 089270571988689

Author(s):

Thiago Felipe Vieira Silva ◽

Marcelo Henrique Stoppa

Keyword(s):

Additive Manufacturing ◽

Magnetic Particles ◽

Permanent Magnets ◽

State Of The Art ◽

Heating Temperature ◽

Maximum Energy ◽

Sintering Process ◽

Capacity Limits ◽

Main Compound ◽

Complex Shapes

Additive manufacturing has been gaining ground both in the industry and in the academic world due to its flexibility, easy operation, and the possibility of making products in the most varied formats. Also, it can be observed that magnets are largely produced using a sintering process, although it results in high (BH)max, this process is very limited in relation to the shapes of the magnets, thus, additive manufacturing can be used to produce complex shaped magnets. The aim of this article is to demonstrate the state of the art regarding the applied methods to produce permanent magnets and materials for magnet production. Considering this, a literature review was conducted using the methodology called mapping study to select the articles to be used, thus, demonstrating that the main compound used as the magnetic particle is NdFeB alloy powder. Finally, it can be concluded that the magnets produced by additive manufacturing have lower (BH)max than those produced by sintering processes, which despite having high filling capacity of magnetic particles increases the magnet’s magnetic capacity, limits their shape, those by manufacturing magnets can be produced with complex shapes, the heating temperature may reduce the maximum energy, and the coercive force improves it.

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Additive Manufacturing of Anisotropic Sm-Fe-N Nylon Bonded Permanent Magnets

10.22541/au.163255721.17079465/v1 ◽

2021 ◽

Author(s):

Kinjal Gandha ◽

Mariappan Paranthaman ◽

Brian Sales ◽

Haobo Wang ◽

Adrian Dalagan ◽

...

Keyword(s):

Additive Manufacturing ◽

Magnetic Particles ◽

Permanent Magnets ◽

Cost Effective ◽

Maximum Energy ◽

Maximum Energy Product ◽

Polyamide 12 ◽

Energy Technologies ◽

Energy Product ◽

Bonded Magnet

Fabricating a bonded magnet with a near-net shape in suitable thermoplastic polymer binders is of paramount importance in the development of cost-effective energy technologies. In this work, anisotropic Sm2Fe17N3 (Sm-Fe-N) bonded magnets are additively printed using Sm-Fe-N anisotropic magnetic particles in a polymeric binder polyamide-12 (PA12). The anisotropic bonded permanent magnets are fabricated by Big Area Additive Manufacturing followed by post-aligned in a magnetic field. Optimal post-alignment results in an enhanced remanence of ~ 0.68 T in PA12 reflected in a parallel-oriented (aligned) measured direction. The maximum energy product achieved for the additively printed anisotropic bonded magnet of Sm-Fe-N in PA12 polymer is 78.8 KJ m-3. Our results show advanced processing flexibility of additive manufacturing for the development of Sm-Fe-N bonded magnets in polymer media designed for applications with no critical rare earth magnets.

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Additive Manufacturing of Bulk Nanocrystalline FeNdB Based Permanent Magnets

Micromachines ◽

10.3390/mi12050538 ◽

2021 ◽

Vol 12 (5) ◽

pp. 538

Author(s):

Dagmar Goll ◽

Felix Trauter ◽

Timo Bernthaler ◽

Jochen Schanz ◽

Harald Riegel ◽

...

Keyword(s):

Additive Manufacturing ◽

Melt Spinning ◽

Permanent Magnets ◽

Maximum Energy ◽

Laser Melting ◽

Powder Bed ◽

Melt Pool ◽

Bulk Nanocrystalline ◽

Ribbon Structures ◽

Nanocrystalline Ribbon

Lab scale additive manufacturing of Fe-Nd-B based powders was performed to realize bulk nanocrystalline Fe-Nd-B based permanent magnets. For fabrication a special inert gas process chamber for laser powder bed fusion was used. Inspired by the nanocrystalline ribbon structures, well-known from melt-spinning, the concept was successfully transferred to the additive manufactured parts. For example, for Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8 (excess rare earth (RE) = Nd, Pr; the amount of additives was chosen following Magnequench (MQ) powder composition) a maximum coercivity of µ0Hc = 1.16 T, remanence Jr = 0.58 T and maximum energy density of (BH)max = 62.3 kJ/m3 have been achieved. The most important prerequisite to develop nanocrystalline printed parts with good magnetic properties is to enable rapid solidification during selective laser melting. This is made possible by a shallow melt pool during laser melting. Melt pool depths as low as 20 to 40 µm have been achieved. The printed bulk nanocrystalline Fe-Nd-B based permanent magnets have the potential to realize magnets known so far as polymer bonded magnets without polymer.

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Bulk Nanocrystalline Permanent Magnets by Selective Laser Melting

Practical Metallography ◽

10.1515/pm-2021-0055 ◽

2021 ◽

Vol 58 (10) ◽

pp. 630-643

Author(s):

F. Trauter ◽

J. Schanz ◽

H. Riegel ◽

T. Bernthaler ◽

D. Goll ◽

...

Keyword(s):

Additive Manufacturing ◽

Field Strength ◽

Selective Laser Melting ◽

Permanent Magnets ◽

Maximum Energy ◽

Laser Melting ◽

Maximum Energy Product ◽

Energy Product ◽

Bulk Nanocrystalline ◽

Micrometer Scale

Abstract Fe-Nd-B powders were processed by additive manufacturing using laboratory scale selective laser melting to produce bulk nanocrystalline permanent magnets. The manufacturing process was carried out in a specially developed process chamber under Ar atmosphere. This resulted in novel types of microstructures with micrometer scale clusters of nanocrystalline hard magnetic grains. Owing to this microstructure, a maximum coercive field strength (coercivity) μ0Hc of 1.16 T, a remanence Jr of 0.58 T, and a maximum energy product (BH)max of 62.3 kJ/mm3could, for example, be obtained for the composition Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8.

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Microstructure Of Fe-Nd-B Alloys Tailored To Approach Theoretical Coercrvtty Limits

Microscopy and Microanalysis ◽

10.1017/s1431927600013453 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 26-27

Author(s):

Kannan M. Krishnan ◽

Er. Girt ◽

E. C. Nelson ◽

G. Thomas ◽

Ferdinand Hofer

Keyword(s):

Magnetic Particles ◽

Permanent Magnets ◽

Spontaneous Magnetization ◽

Particle Interaction ◽

Maximum Energy ◽

Interacting Particles ◽

Maximum Energy Product ◽

Energy Product ◽

Oriented Samples ◽

The Difference

Performance of permanent magnets for a variety of applications is often determined by the maximum energy product (BH)max. In order to obtain high (BH)max permanent magnetic materials have to have large coercivity. In theory the coercive field of ideally oriented, non-interacting, single domain, magnetic particles, assuming Kl is much bigger than K2, was shown to be He = 2K1/Ms - N Ms, where Kl and K2 are the magnetocrystalline anisotropy constants, Ms is the spontaneous magnetization and N is the demagnetization factor. For randomly oriented non-interacting particles the Stoner-Wohlfarth model predicts that the value of Hc decreases to about half. However, experimentally obtained values of the coercitive fields in permanent magnets are 3 to 10 and 2 times smaller for well oriented and randomly oriented samples, respectively. This discrepancy was attributed to inter-particle interaction and the microstructure of the permanent magnets. In order to understand the difference between the theoretically predicted and experimentally obtained results for He we prepared rapidly quenched, Nd-rich, NdxFe14B (2 < x < 150) ribbons.

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Additive Manufacturing of Textured FePrCuB Permanent Magnets

Micromachines ◽

10.3390/mi12091056 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1056

Author(s):

Dagmar Goll ◽

Felix Trauter ◽

Ralf Loeffler ◽

Thomas Gross ◽

Gerhard Schneider

Keyword(s):

Heat Treatment ◽

Additive Manufacturing ◽

Permanent Magnets ◽

Maximum Energy ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Mold Casting ◽

Metallurgical Processing ◽

Hard Magnetic Properties ◽

Stage Heat Treatment

Permanent magnets based on FePrCuB were realized on a laboratory scale through additive manufacturing (laser powder bed fusion, L-PBF) and book mold casting (reference). A well-adjusted two-stage heat treatment of the as-cast/as-printed FePrCuB alloys produces hard magnetic properties without the need for subsequent powder metallurgical processing. This resulted in a coercivity of 0.67 T, remanence of 0.67 T and maximum energy density of 69.8 kJ/m3 for the printed parts. While the annealed book-mold-cast FePrCuB alloys are easy-plane permanent magnets (BMC magnet), the printed magnets are characterized by a distinct, predominantly directional microstructure that originated from the AM process and was further refined during heat treatment. Due to the higher degree of texturing, the L-PBF magnet has a 26% higher remanence compared to the identically annealed BMC magnet of the same composition.

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Ultrasound Transducer Array Fabrication Based on Additive Manufacturing of Piezocomposites

ASME/ISCIE 2012 International Symposium on Flexible Automation ◽

10.1115/isfa2012-7119 ◽

2012 ◽

Cited By ~ 10

Author(s):

Hamid Chabok ◽

Chi Zhou ◽

Yong Chen ◽

Arash Eskandarinazhad ◽

Qifa Zhou ◽

...

Keyword(s):

Additive Manufacturing ◽

Ultrasound Transducer ◽

Prototype System ◽

Sintering Process ◽

Projection System ◽

Complex Shapes ◽

Transducer Arrays ◽

Ceramic Components ◽

Digital Micromirror Devices ◽

Future Work

Conventional methods for fabricating ultrasound imaging transducer arrays, especially for high frequency range (>20 MHz), are expensive, time consuming and limited to relatively simple geometries. In this paper, the development of an additive manufacturing (AM) process based on digital micromirror devices (DMDs) is presented for the fabrication of piezoelectric devices such as ultrasound transducer arrays. Both green-part fabrication and the sintering of fabricated green-parts have been studied. A novel two-channel design in the bottom-up projection system is presented to address the piezo-composite fabrication challenges including a small curing depth and viscous ceramic slurry recoating. A prototype system has been developed for the fabrication of green-parts with complex shapes and small features. Based on the fabricated green-parts, the challenges in the sintering process for achieving desired functionality are discussed. Various approaches for increasing the density of sintered components are presented. Dielectric and piezoelectric properties of the fabricated samples are measured and compared with those of bulk PZT samples. Based on the identified challenges in the DMD-based AM process, future work for achieving fully functional piezoelectric ceramic components is discussed.

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EM of rapidly solidified permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121399 ◽

1992 ◽

Vol 50 (1) ◽

pp. 198-199

Author(s):

Raja K. Mishra

Keyword(s):

Melt Spinning ◽

Permanent Magnets ◽

Dark Field Image ◽

Dark Field ◽

Maximum Energy ◽

Quench Rate ◽

Maximum Energy Product ◽

Energy Product ◽

Annular Dark Field ◽

Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

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