Magnetics Business & Technology - Winter 2011 - (Page 8)

FEATURE ARTICLE By Peter C. Dent, VP Business DeVeloPment • eleCtron energy CorP. Rare Earth Future What are the challenges, choices and solutions for the development and production of rare earth permanent magnets? Rare earths have garnered much attention recently as the public becomes aware of the supply-chain issues stemming from China’s dominance of the production these 17 elements. Despite their name, the rare earths are not rare and have abundance in the earth’s crust comparable to tin and antimony. More than 300 deposits around the world are being discussed for potential commercialization. Just because a shovel full of dirt in many parts of the world indicates rare earths are present, however, does not necessarily mean that economic exploitation and commercial production can occur. Today more than 95 percent of rare earth oxides come from China. Data from 2010 indicates that 129,000 metric tonnes of rare earth elements were produced worldwide, with a small nonChinese contribution. Over the past decade China’s dominance in this market has led to a near monopoly in raw materials and has resulted in a steep decline in US and non-Chinese rare earth and magnet production capabilities. So with all this fear and uncertainty surrounding rare earths, why don’t we just avoid their use in new design applications? First, although substantial challenges exist over the next couple of years, new supply operations outside China are being aggressively developed, and governments and investors worldwide are working to fill in non-Chinese supply-chain gaps that can be sustainable over the long term. Second, Mother Nature has blessed these elements of the periodic table with unique characteristics that can produce much higher magnetic fields than anything else discovered so far. Magnet Technology Overview Up through the 1960s most permanent magnets were based on iron in combination with other transition metals such as cobalt and nickel. To this day, based on tonnage, the dominant magnet material by a very wide margin is ferrite, which is essentially a form of iron oxide. Non-rare earth magnets have been available for decades in the form of ferrites and aluminium nickel cobalt (alnico). In the 1960s, researchers at Wright Patterson Air Force base discovered a new class of magnets based on the rare earth metal samarium and the transition metal cobalt. Rare earth magnets were born. In the 1980s, neodymium iron boron, another rare earth-transition metal magnet, was developed in Japan and the US. Rare earth magnets owe their superior properties, high induction and coercive force, to the unique combination of elements with unfilled ‘d’ and ‘f’ orbitals, in other words transition metals and rare earths. The combination of these elements and others allows the electrons in the alloy structure to align with one another anisotropically and obtain much higher residual induction, with a much higher resistance to being demagnetized, or intrinsic coercivity, than previous material systems. A chart showing the relative strengths as measured by maxi- Figure 1. Magnet Performance mum energy product and maximum continuous operating temperature is shown in Figure 1. One can see the trend over time in the development of higher energy product magnets, which has been transferred into commercial acceptance as well. Around the year 2000, rare earth magnets eclipsed non-rare earth magnets in dollar volume of sales worldwide, even though they can be five to 20 or more times more expensive per kilogram than nonrare earth alternatives. The primary reason for this shift is due to higher magnetic flux per unit mass. This not only reduces magnet sizes but also reduces system costs by making surrounding components smaller. This helps to miniaturize the devices and therefore expand uses and broaden market penetration. Future Permanent Magnetic Materials for Motors & Generators For at least the next 10 years rare earth magnets will continue to be the material of choice for hybrid electric vehicle (HEV) internal permanent magnet (IPM) motor and generator designs as well as for higher speed, more compact brushless DC (BLDC) motor applications. Alternatively, synchronous electrical machines also serve an important role in motor and generator applications for a broad array of applications including HEVs where challenges occur in generating the low-speed torques required, especially at lower ambient temperatures. Due to rare earth supply chain issues, some customers are currently re-designing and qualifying systems by replacement of higher dysprosium Nd-Fe-B magnets with samarium cobalt magnets whose properties in some cases can be very similar or even exceed performance of the original material. In addition, ferrite and alnico magnets can offer customers choices, however the gap between their performance and Nd-Fe-B is higher. EEC is developing magnet technologies that will offer new classes of rare earth permanent magnets with high electrical resistivity. Fully dense sintered rare earth magnets are brittle intermetallics that have inherently low electrical resistivity. EEC’s 8 Magnetics Business & Technology • Winter 2011 www.MagneticsMagazine.com http://www.MagneticsMagazine.com

Table of Contents for the Digital Edition of Magnetics Business & Technology - Winter 2011

Magnetics Business & Technology - Winter 2011
Editor's Choice
Rare Earth Future
Research & Development
Passive Magnetic Bearing Prototype Testing Results
Magnets • Materials • Measurement
Application • Component Developments
MAGNETICS 2012 Conference Preview
2011 Resource Guide
Volatility in the Rare-Earth Material Markets – Some Benefits After All
Marketplace
Spontaneous Thoughts: Is Your Design Optimized?

Magnetics Business & Technology - Winter 2011