Some suppliers of motor materials Andritz Schuler www.andritz.com Arnold Magnetics www.arnoldmagnetics.com Aurubis www.aurubis.com Axalta www.axalta.com Carpenter Technologies www.carpentertechnology.com Electron Energy Corporation www.electronenergy.com Henkel www.henkel.com Heraeus Remloy www.heraeus-remloy.com Nippon Steel www.nipponsteel.com O‘Keefe Ceramics www.okeefeceramics.com Parker Lord www.parker.com Syensqo www.syensqo.com Vacuumschmelze www.vacuumschmelze.com Voestalpine www.voestalpine.com In the domain of electrical steel, post-annealable grades of steel offer the advantage of high strength in the as-delivered condition while achieving excellent magnetic properties after a final annealing step performed by the customer. Furthermore, stressrelief annealing techniques are vital for mitigating material damage induced by punching or cutting processes, thereby preserving the magnetic performance of the laminations. Advanced techniques under investigation to increase aluminium’s conductivity include those characterised as severe plastic deformation. Methods such as equal channel angular pressing and high-pressure torsion can refine the metal’s grain size down to the nanometre scale, creating a nanocrystalline grain structure that facilitates easier current flow. Research suggests that adding small amounts of elements such as cerium and lanthanum can improve the conductivity of aluminium by modifying its electron band structure and reducing impurities. Another approach, involving the incorporation of carbon nanotubes into aluminium, results in a composite material containing highly conductive pathways, significantly increasing overall conductivity and strength. Finally, studies are exploring specific low-alloy compositions (such as Al-Fe-Si, Al-Mg-Si, Al-Fe-Cu with boron treatment and grain refinement) that show promising improvements in terms of electrical conductivity, approaching or even exceeding 60% of the IACS while maintaining reasonable mechanical properties. Even with these advanced materials, the trade-offs between conductivity, mechanical strength, thermal properties, and cost will continue to shape the adoption of aluminium in motor windings for e-mobility applications. Thermally conductive potting for end windings is another promising technology. By effectively dissipating heat from the motor windings, it enables the design of smaller motors with higher power output and improved durability. The development of bonding varnishes and Backlack coatings with enhanced thermal conductivity also contributes significantly to improved thermal management within the motor core. In the longer term, superconducting materials developed to work at higher temperatures could be practical for e-mobility applications, offering significantly reduced resistive losses in windings. The constant push toward higher efficiencies to achieve cheaper, more sustainable vehicles with longer range (or the same range with smaller batteries) is an overriding industry trend. The shift toward 800 V and SiC technologies has increased interest in thermoplastic materials with higher PDIV and breakdown voltage per thickness. However, the benefits of thinner, mechanically robust thermoplastic films are also evident in 400 V systems, allowing for miniaturisation and reduced material usage. One of the most critical aspects for sustainability is reducing raw material use while maintaining performance. More efficient designs, enabled by materials like thinner, high-performing insulation, allow for miniaturisation, leading to a lower carbon footprint for both the e-motor (potentially a 10% reduction) and the battery pack (1–2% reduction). Balancing cost, performance and sustainability Increasingly, engineers must consider the environmental impact of their material choices throughout the motor’s life cycle from extraction to disposal. Of the materials used in motors, rare earth magnets are arguably the most problematic in this respect because of the impacts associated with their mining and processing. Sustainable sourcing, recycling and, where practical, material substitution come to the fore here. This also affects design as much as material selection priorities because motors must be easy to disassemble for recycling. The selection of materials for e-motors in the coming 5–10 years will be increasingly influenced by the evolving interplay between performance, cost and sustainability. In many cases, these goals are mutually reinforcing. Acknowledgements The author would like to thank the following for their help with this article: Wolfgang Schumann, e-mobility product manager at ANDRITZ Schuler; Matthias Brachmann, e-mobility business development manager at Henkel; Alexander Buckow, co-head Heraeus Remloy; Eric Wyman, business development manager, and Dan Barber, application engineer, at Parker Lord; Luigi Marino, global marketing manager at Syensqo; and Roman Sonnleitner. product manager at Voestalpine. Product focus | Motor materials May/June 2025 | E-Mobility Engineering 72
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