Rare earth elements have many important applications, particularly for defense and national security, so problems in their supply may have political implications. Mr. Matt Zolnowski, from J.A. Green & Company, comments on this issue.
Rare Earth Elements
Rare earth elements are the lanthanide elements of the periodic table – in the Figure on the side, these are the two lines at the bottom. Yttrium (Y) and scandium (Sc) are also considered rare earths.
The importance of these elements for technological applications is well known; the development of several green technologies, for instance, is heavily dependent on the use of rare earth metals.
Beyond green technology, rare earth elements also are essential for the fabrication of many high-profile weapon systems employed by the United States and by other western European countries; some examples are shown in the picture on the side.
- Manufacturers use rare earth metals to make some very powerful magnets in weapon systems and flight control surfaces.
- Some precision-guided munitions, such as the Joint Direct Attack Munition (JDAM) and the HELLFIRE missile (AGM-114), use samarium-cobalt or neodymium-iron-boron permanent magnets. These magnets drive the servo-motors in fins, and larger systems like the F-35 Lightning II use these magnets for articulating parts, like flaps or landing gear.
- The defense forces also employ other devices using rare earth-based magnets, such as radar and wireless microwave / GHz communications.
- In addition to magnets, ceramics based on zirconia and containing yttrium (YSZ, yttria-stabilized zirconia) create thermal barrier coatings in various parts of the aircraft such as turbines and engines, to prevent overheating and catastrophic failure.
- Aside from this direct application by militaries, aerospace companies utilize yttrium-based ceramics for the investment casting of metal parts, such as integrally bladed rotors or “blisks.” Some laser target designators and/or interrogators, used in tanks for instance, employ yttrium-based garnets (e.g., yttrium-aluminum or yttrium-iron).
Rare Earth Elements Supply
The few examples reported above show that the importance of rare earth elements is not confined just to a specific field but involves many technological applications crucial for our society, and particularly defense. It is therefore essential to have a supply of these elements which is sufficient to match the increasing demand.
From this point of view, one problem is the distribution of rare earth metals throughout the world, and their consequent global production. According to a US geological Survey, 95 % of rare earth elements output is produced by China; this dominant position could cause problems, as any reduction in supply would have political implications.
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