Developing an anisotropic version is key to performance. Hadjipanayis’ group is taking a divide-and-conquer approach of separately synthesizing hard and soft nanoparticles that they will then bind together to form magnets. The issue is that exchange coupling is a short-range interaction, effective at distances below 20 nm, so the nanoparticles need to remain at a size compatible with that. If the team can overcome the difficulties, though, the approach has a theoretical energy product of as much as 100 MGOe.
One of the continuing challenges in nanotechnology is manufacturing. The issues are multifold: researchers not only need to find methods to synthesize the nanoparticles, the process needs to be scalable to volume production. Sometimes, the techniques are high tech, but sometimes they're surprisingly lowbrow.
At the University of Texas, physicists have developed a method for fabricating anisotropic bonded magnets using surfactants -- basically, soap. Led by physicist Ping Liu, the group starts with neodymium-iron-boron and samarium cobalt, ball-milling the materials in solution with surfactants to produce high-aspect-ratio nanochips with coercivities as high as 26 MGOe. They mix the chips with organic binders, then press the material together into magnets under a 20-kOe magnetic field. Applying the field helps align the chips to yield anisotropic magnets with energy products of 19.1 MGOe.
Other projects are even more ambitious. At the US Department of Energy’s Ames Laboratory, researchers are working to develop permanent magnets that use cerium, a rare earth element far more available and economical than neodymium. Led by senior metallurgist William McCallum, the team is investigating alloys that could yield temperature-tolerant magnets for electric vehicle motors. They've teamed with Molycorp Minerals LLC, which runs the resurgent Mountain Pass mine in California, as well as General Motors.
Meanwhile, a separate group at Ames Laboratory is collaborating with researchers at the Pacific Northwest National Laboratory to develop a nanostructured manganese bismuth magnet that holds out the prospect of an energy product of 40 MGOe at 200C.
As with all research that explores fundamentally new technologies, these projects will not come to fruition for a long time, if ever. Even removing the economic argument for pursuing alternatives to rare earth permanent magnets, logistical and environmental concerns still make the effort worthwhile. Research like this not only promises a fresh take on magnets, it could be laying groundwork for entirely new technologies and industries.
Next:
In part four of this five-part series, we'll look at permanent-magnet motors that use flux focusing in three dimensions to get REE-free performance without the REEs.
Misconception #12: Mountain Pass stopped producing rare earth elements in 2002
Mountain Pass has never stopped producing rare earth elements in the facility's almost 58 years of operation. However, in 2002 mining of fresh ore to feed the processing systems came to a halt due to a lack of tailings basin capacity and of a new permit to expand the old basin or build a new one. After numerous upgrades and revisions to resolve the issues, Molycorp is poised to restart mining of fresh ore as early as 2011 to ensure its mill can be fed by the middle of 2012.
The thing to keep in mind is that the mineral pricing is a two way street, especially when you are talking about the fact that we in the US have some of the largest deposits of some of these rare earths. The associated problem, and something that we can do do something about to minimized the games that other countries are playing, is to encourage the development of our own natural resources. The current environment is not conducive to that.
The green tariff is a pretty good idea, David. I could create a playing field that is closer to level. Yet I can't see it happening in our current political environment. Like any commodity, rare earths will sort themselves out as mines across the world are sparked into action by higher prices.
RE materials, such as neodymium and dysprosium (magnet material), are very rare in practical minable reserves (period). Yet, the small number of electric vehicles and wind turbines with high performance PM motors has been one reason for making the price of these RE materials increase dramatically. If EV and Wind turbines become more common as anticipated, there is question whether all the practical minable reserves (including reopening mines) can satisfy the demand. This is the subject worth looking into!
Rare Earth "Shortage" ???Rare earths are NOT rare, to the contrary, most are more common in the earth's crust than Copper. However, 'rare earths' are in the Lanthanum group of elements and therefore their ores are often comingled with radioactive elements such as Uranium and Thorium.As environmental rules were enacted in the 70's and 80's, rare earth refining was foolishly outsourced to nations without pesky EPA and OSHA regulations.
Our "Free Trade" policy exacerbated this outsourcing, so that today 90% of the refining capacity has migrated to nations that frankly don't care about worker exposure to radiation or what environmental damage is wrought when the tailings are dumped in streams and rivers.
A 'Green Tariff' on imports which are produced in facilities which do not abide by effective environmental or workplace safety regulations would level the playing field between offshore and domestic suppliers, and the increased competition would prevent artificial 'shortages' of these strategic materials.
I agree, Roddalitz. The advantage of replacing the materials is that they could find a replacement that is readily available and perhaps superior. If there's one thing we're learned from oil, shortages will just keep coming back and coming back.
Although REEs may become readily available again, the experience and knowledge gained by replacing them may help to create far better magnets using REEs.
China needs us way more than we need them. Somebody is playing games. If someone would "follow the money" ---? I think we could find out why US is so complacent about this.
It's amazing the influence that commodity markets is playing on design and manufacturing. It would be great if supply and demand, rather than external factors, would be the driving force in the cost of materials such as rare earth magnets. Anything close to an 8-9% increase in the price of servomotors for 2012 would be significant.
Good points, Kristin. Saudi Arabia is facing a similar fate. They have voiced concerns that if oil stays above $80 per barrel, the world will seek alternatives. They apparently wanted to keep oil down at $80, but they have been unsuccessful. At the high rates, they're correct, the world will find alternatives.
We looked at a number of sources to determine this year's greenest cars, from KBB to automotive trade magazines to environmental organizations. These 14 cars emerged as being great at either stretching fuel or reducing carbon footprint.
Researchers at MIT and Sandia National Labs have observed a reaction in lithium-air batteries that could help improve the design of these cells for electric vehicles and other applications.
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