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.
<<At some point, rare earth elements will be plentiful again...speculators may be shooting themselves in their collective foot.>>
I think they figure that out late last fall, which is why the price started dropping. Prices got so high that more and more engineers at all levels of the food chain started looking for alternatives, Which may demand drop. All of a sudden, The speculators got worried they'd be stuck with a bunch of metal in a warehouse, so they started dumping inventory onto the market.The price of both neodymium and dysprosium are severalfold higher than they were in 2010, even, but they're down 30 and 40% from where they were at the height last summer.
That's a good question, naperlou. I have a query out to one of my motor guys to see what he has to say about it. Obviously, that rule of thumb is likely to be wildly distorted over the past several years, which explains the introduction of the magnet surcharge.
No question that prices are up. On the motor side, I tend to talk to engineers rather than sales folks, so I don't have exact numbers.Last November, IMS Research analyst Jenelea Howell predicted that the average price of servomotors would jump by 9.3% in 2012. That number may have softened because of stabilizing prices for REEs, but the materials are still up significantly from their price of four or five years ago. In some cases, manufacturers have written the cost into their contracts, along the lines of the fuel surcharge that airport limo services began using a few years ago. Lenze, For example, has a page on their website explaining a fuel surcharge that scales for increasing neodymium and dysprosium prices relative to their March 2011 values.
That's a really good question, Naperlou. With new sources found in Afghanistan, a mine again active in Australia and working getting down to create alternatives to rare earth elements, it seems inevitable the supply will exceed demand in a few short years.
I agree, Naperlou. And the only way we can get past the adversity is to have lots of competitive projects motivated by a sense of urgency. As a rule, materials innovation doesn't happen in a rush.
One interesting point to remember is that the mines in the US closed down becuase prices had dropped so much. What happens next time they drop? Do we become dependent on another supplier that will manipulate the price for their own purposes?
At some point, rare earth elements will be plentiful again. Mines in the U.S., Australia and Afghanistan will begin producing plenty of materials. By then, however, alternatives may be available. Speculators may be shooting themselves in their collective foot.
apresher, that is an interesting question. Another way to ask that is to ask what is the typical percentage of the cost of a motor that the magnets comprise. Is there any rule of thumb on that, Kristin?
Beth, this is a good example of adversity spurring innovation. While some of the techniques and technologies may not pan out, they may well lead to new discoveries themselves. I am especially impressed by the efforts in nano materials that this entails.
Kristin, Excellent article. Any idea how much price premium % the shortage of REEs is adding to permanent magnet motors? I'm curious how much of an impact the shortage might have in this area. Also, wondering if the performance of the new materials will meet or surpass current performance standards. Thanks.
New disc magnet motors fit into the design trend of stepping up to closed loop performance while maintaining the cost advantage of stepper motor technology.
At the Design News webinar on June 27, learn all about aluminum extrusion: designing the right shape so it costs the least, is simplest to manufacture, and best fits the application's structural requirements.
A new battery design, which replaces lithium with abundant and low-cost elemental sulfur, is still in its nascent stages but shows real promise for giving batteries more energy potential.
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