Soft magnetic composites allow for revolutionized designs of electromagnetic devices to aid in improved efficiency and reduced weight and costs, without sacrificing magnetic performance. Electrically insulated core powder are formed into toroid shapes and tested for core loss and magnetic permeability, which are desired to be minimized and maximized, respectively. Ferromagnetic powder has shown the most potential as core materials, however nanocrystalline materials are highly resistive and amorphous materials have benefits of very low coercivities. Likewise, organic and inorganic coating materials have been explored for the reduction of eddy currents to improve overall core losses at higher frequencies. The balance between properties is of the utmost concern for SMC applications.
Our world is focused on making devices faster, lighter, and more innovative; why should electric motors be any different? Electric motors convert electrical energy to mechanical energy using direct current (DC) from stored energy, say in batteries, or alternating current (AC) from generators or the power grid. They are found in electric cars, small house hold appliances, industrial fans and pumps, machine tools, as well as in large ships and planes for propulsion. Continuous research on soft magnetic composites (SMCs) has shown their vast potential for DC and AC applications that improve the magnetic induction of core materials at low to high applied frequencies by allowing new innovative designs developed by engineers. SMCs are comprised of electrically insulated ferromagnetic powder that allow for several worthy advantages when particle size, shape, and microstructure are optimized. These unique properties include magnetic and thermal isotropy, high magnetic permeability, low coercivity, high Curie temperatures, and low total core losses. In addition, the nature of powder metallurgy allows customers to reduce the material consumption with a smaller motor design or obtain higher power from similar dimensions as their current electric motors, which opens up an enormous market for electromagnetic devices. These components have the ability to bridge the gap between traditional laminated steel cores limited to frequencies of a few hundred Hz and ferrite cores limited to above a few MHz. The elimination of failure/overheating of motors often because of eddy current buildup resulting from poor insulation of ferromagnetic layers can be completed with SMC materials.
This article appeared in the November–December 2017 issue of Metal Powder Report.