Toyota Develops New Magnet for Electric Motors Aiming to Reduce Use of Critical Rare-Earth Element by up to 50%.
World's first neodymium-reduced, heat-resistant magnet developed by Toyota, Key element of the foundation required to popularize electrified vehicles.
Toyota City, Japan, Feb 20, 2018 – (JCN Newswire) – Toyota Motor Corporation announces that it has developed the world’s first(1) neodymium-reduced, heat-resistant magnet. Neodymium magnets are used in various types of motors such as the high-output motors found in electrified vehicles, use of which is expected to increase rapidly in the future. The new magnet uses significantly less neodymium, a rare-earth element(2), and can be used in high-temperature conditions.
The newly developed magnet uses no terbium (Tb) or dysprosium (Dy), which are rare earths that are also categorized as critical materials(3) necessary for highly heat-resistant neodymium magnets. A portion of the neodymium has been replaced with lanthanum (La) and cerium (Ce), which are low-cost rare earths, reducing the amount of neodymium used in the magnet.
Neodymium plays an important role in maintaining high coercivity (the ability to maintain magnetization) and heat resistance. Merely reducing the amount of neodymium and replacing it with lanthanum and cerium results in a decline in motor performance. Accordingly, Toyota adopted new technologies that suppress the deterioration of coercivity and heat resistance, even when neodymium is replaced with lanthanum and cerium, and developed a magnet that has equivalent levels of heat resistance as earlier neodymium magnets, while reducing the amount of neodymium used by up to 50 percent.
This new type of magnet is expected to be useful in expanding use of motors in various areas such as automobiles and robotics, as well as maintaining a balance between the supply and demand of valuable rare earth resources. Toyota will work to further enhance performance and evaluate application in products while accelerating the development of mass production technologies, with the aim of achieving early adoption in motors used for various applications, including in automobiles and robotics.
Development of elemental technologies for motors, inverters, batteries, and other components will require steady research and development in anticipation of the future. Toyota positions these technologies as essential for electrified vehicles and will continue making steady progress in each and every area, while working to build the foundation that will support the increased use of electrified vehicles in the future.
The newly developed Nd-reduced, heat-resistant magnet is able to maintain coercivity even at high temperatures because of the combination of the following three new technologies:
It is now possible to retain high coercivity at high temperatures through the reduction of the size of the magnet grains to one-tenth or less of those found in conventional neodymium magnets and the enlargement of the grain boundary area.
2. Two-layered high-performance grain surface.
In a conventional neodymium magnet, neodymium is spread evenly within the grains of the magnet, and in many cases, the neodymium used is more than the necessary amount to maintain coercivity. Thus, it is possible to efficiently use neodymium by increasing the neodymium concentration on the surface of the magnet grains, which is necessary to increase coercivity, and decreasing the concentration in the grain core. This results in the reduction of the overall amount of neodymium used in the new magnet
If neodymium is simply alloyed with lanthanum and cerium, its performance properties (heat resistance and coercivity) decline substantially, complicating the use of light rare earths. As a result of the evaluation of various alloys, Toyota discovered a specific ratio at which lanthanum and cerium, both abundant and low-cost rare earths, can be alloyed so that the deterioration of properties is suppressed.
Read more at: https://www.eejournal.com/industry_news/toyota-develops-new-magnet-for-electric-motors-aiming-to-reduce-use-of-critical-rare-earth-element-by-up-to-50/
Photo Credit: https://paultan.org/2018/02/22/toyota-develops-new-neodymium-reduced-magnet/