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Bonded magnetic composites combine the cost-effectiveness, low density, and manufacturing flexibility of conventional polymer binders with the unique magnetic characteristics of magnetic powders/fillers to form multifunctional magneto polymeric composites that offer superior properties to conventional sintered magnets. In this study, a co-rotating twin screw extruder was used to fabricate 20 and 40 wt.% strontium ferrite/polyamide 4.6 bonded magnetic composites viable for fused filament fabrication 3D printing. The characterization conducted on the bonded magnetic composites was scanning electron microscopy, simultaneous differential thermogravimetry, and vibrating sample magnetometry. The microstructure of the bonded composite exhibited a uniform platelet morphology of the strontium ferrite magnetic particles. There was no observable depreciation in the melting transitions, which suggests a thermally resistant magnetic composite. An appreciable increment in % crystallinity of 13 and 20% for 20wt. % and 40wt. % strontium ferrites bonded magnets were observed. This is attributable to the heterogeneous nucleation phenomenon, where the metal powders act as nucleation sites for increased crystalline domains. The bonded composite exhibited significant magnetic anisotropy, with the remanence (Mr), which is the most important property for magnetic application significantly increasing to 49.8% along the easy direction in comparison to the hard axis. This suggests the viability of the fabricated bonded composites in viable in producing anisotropic bonded magnetic devices, which are considered to exhibit stronger magnetic properties.
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This content will become publicly available on July 25, 2026
Review on mechanical, thermal, and magnetic performance of high-temperature thermoplastic bonded magnetic composites
Thermoplastic bonded magnetic composites combine the cost-effectiveness, low mass density, and manufacturing flexibility of conventional thermoplastics with the unique characteristics of magnetic powders/ fillers to form multifunctional magneto polymeric composites that offer superior properties to conventional materials. At elevated temperatures, the magnetic properties change significantly, and the polymer matrix no longer secures the magnetic particles and can rotate freely with respect to an externally applied magnetic field. This often happens at temperatures significantly below the melting point of the polymer. To extend the thermal window of bonded magnets beyond 175 ◦C (the typical temperature of rotors in motors and generators), poly- mers such as polyetheretherketone (PEEK), polyetherimide (PEI), or other high-temperature thermoplastics have been considered suitable binders for magnetic fillers. Another suggested approach is using a surface treatment to increase the adhesion between the polymer matrix and magnetic particles. In this review, the fabrication pro- cesses to make bonded magnets by injection molding and fused filament fabrication were discussed as well as their thermal, mechanical, and magnetic performance obtained via analytical and materials characterization methods. The magnetic properties of bonded permanent magnets manufactured via different techniques were discussed in terms of the most important single magnetic parameter known as “the maximum energy product- (BH)max, which can serve as a performance index for manufacturing bonded magnets. The energy product normalized on cost or mass density are used to provide insight on the performance of bonded magnets for ap- plications driven by cost or inertia. Finally, applications of high-performance thermoplastic-based magnetic composites that can be viable for stringent engineering devices such as sensors, actuators, motors, and generators were highlighted.
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- Award ID(s):
- 2216440
- PAR ID:
- 10644317
- Editor(s):
- Zheng, Hao
- Publisher / Repository:
- www.elsevier.com/locate/jmmm
- Date Published:
- Journal Name:
- Journal of magnetism and magnetic materials
- Volume:
- 630
- ISSN:
- 1873-4766
- Page Range / eLocation ID:
- 173394
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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