Rare Earth Elements in the Magnets Application Field
After the data dilemma has been described, that a lot of data and information exists but as well manifold inconsistent data sets are around which are usually not addressed now the focus is put towards the magnet materials to illustrate a new approach to c
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Rare Earth Elements in the Magnets Application Field
After the data dilemma has been described, that a lot of data and information exists but as well manifold inconsistent data sets are around which are usually not addressed now the focus is put towards the magnet materials to illustrate a new approach to contribute to a partial solution for the problem. First some basics about magnets and magnet technology have to be explained. Probably magnet specialists will call these short explanations trivial but it is expected that even some basic features are not common knowledge to people in other disciplines. Du and Graedel [1] state that typically permanent magnets contain proportions of Nd (*70 %), Pr (*25 %), Dy (5 %), Gd (2 %) and Tb (0.2 %). This typical consistency could not be validated, as will be shown by the analysis performed in this work; indeed exactly the many different recipes of the magnets affect the very special features and characteristics. For the supply side it is therefore very important to know the exact quantitative needs in order to start suitable actions. After a short explanation of some terms and basic applications the data of the own research will be detailed.
5.1 REE Based Permanent Magnets The general use of magnets can be traced back to about 600 B.C. when lodestones were used by the people in the Iron Age. In the Middle Ages iron was detected for its magnetic characteristics and in the advent of industrialization in the 1930s the first AlNiCo magnets were invented. The permanent magnet technology got a decisive advance with the discovery of the strong Samarium-Cobalt (SmCo) magnets in the late 1960s. Two main SmCo type magnets are common: the SmCo5 and the Sm2Co17. A problem at that time was the low availability and high price of Samarium and, to a lesser extent, of Cobalt. Thereafter, in the early 1980s, the invention of RE2TM14B magnets (RE—rare earth, TM—transition metal, B— boron) offered a cheaper and better alternative to the SmCo magnets [2, p. 54f]. The RE used in this new type of magnets is generally Nd with the common formula Nd2Fe14B. Numerous patents have been issued in the course until today V. Zepf, Rare Earth Elements, Springer Theses, DOI: 10.1007/978-3-642-35458-8_5, Springer-Verlag Berlin Heidelberg 2013
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5 Rare Earth Elements in the Magnets Application Field
with slight deviations in materials composition and manufacturing of the magnets. Soon after these discoveries the RE based permanent magnets were brought into various products, mostly small electric motors but also in hard drives in the computer industry which was growing strongly at that time. Soon the potential of the magnets was obvious so that these strong REE based permanent magnets (REPM) got special attention as they allow better performance on one side and miniaturization which is usually accompanied by smaller product sizes and thus better overall efficiencies. Some very basic terms and simple explanations are given next as more information is detailed in a variety of literature about (permane
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