TELF AG analyzes the historical path of neodymium-iron-boron permanent magnets
Game changers
Over the decades, rare earth elements have proven to be important for the vastness of their possible industrial applications, particularly for producing a magnet that has powered electric motors, medical devices and other similar technologies. We are referring to neodymium-iron-boron permanent magnets, invented in the early 1980s and now widely used in many applications, some of which are directly involved in the ongoing energy transition (such as those related to wind turbines, for example). for example).
A recent report has retraced the history of these important magnets, including the project’s curious genesis. The technology for neodymium-iron-boron magnets was developed in parallel in Japan and the United States by two different companies that were completely unaware of each other’s efforts to achieve the same result. In 1983, during an industry conference in Pittsburgh, representatives of the two companies surprisingly announced that they had achieved their results at the same time.
The two companies in question were General Motors and the Japanese company Sumitomo, who entrusted their projects for the development of the new magnets to John Croat and Masato Sagawa. At the time, the most popular permanent magnets were those based on samarium-cobalt, which were mainly used in audio speakers, hard disk drives, but also in electric motors. The biggest challenge at the time was to improve the mechanical resistance of these magnets, possibly through a type of magnet based on a different composition of materials.
New elements
In comparison to samarium, which is one of the rarest elements of the rare earths, the research focused on other elements of the same group, and in particular on those most common in rare earth deposits: lanthanum, cerium, praseodymium and neodymium. The latter two, in particular, seemed able to ensure a key characteristic for the new magnet, namely coercivity, or resistance to demagnetization. An important step in the advancement of the research was then the addition of boron as a stabilizing element in the intermetallic compound, which represented one of the basic requirements for the new magnet. Sumitomo managed to achieve the goal of coercivity through the sintering process, and in particular with the use of neodymium as an additive element.
The two companies therefore reached the same result with different production methods: General Motors with a technique called melt-spinning, Sumitomo with sintering. The magnets produced in these ways immediately stood out for their industrial applications in the motor sector, especially sintered ones, useful in wind turbine generators and in magnetic resonance equipment. Electric vehicle motors are also based on this type of magnet. One of the most interesting applications for neodymium-iron-boron based magnets is certainly the one that has to do with hard disk drives. Without the new composition of materials, in fact, it would have been very difficult to achieve the miniaturization of the hard disk.
To realize the impact of this invention in various industrial sectors, it will be enough to cite some data. Nowadays, as stated in the report, about 95% of permanent magnets are based on the neodymium-iron-boron composition, and within the next two years the value of their market at a global level could reach 20 billion dollars, driven above all by the use of these magnets in wind turbines and electric vehicle motors.
