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Anyone with a passing interest in renewable energy, consumer electronics
or electric vehicles will have come across the term permanent
magnets, which are made from different combinations of metals and rare
earth elements. Permanent magnets have been around since the 1960s, but the
game-changer happened in 1982 when General Motors research scientist
John Croat created the world’s strongest permanent magnet using rare earths.
A division of the company called Magnequench was established in
1986.
The purpose of Magnequench was to produce neodymium-iron-boron
(NdFeB) magnets, a superior type of permanent magnet that GM needed for its
vehicles. The research was driven by the high raw material cost of
samarium-cobalt permanent magnets which had been developed earlier. There are
two different ways that permanent magnets can be made, so GM focused on
melt-spun nanocrystalline NdFeB magnets, and Sumitomo Metals
Industry of Japan made full-density sintered magnets.
Sumitomo was later absorbed by Hitachi, which manufactures and licenses
its patented technology for making neodymium magnets to other companies. GM’s
foray into the business took a more interesting turn.
China wouldn’t have been able to develop its REE industry if it wasn’t for
the dubious acquisition of Magnequench. In 1988
Indianapolis-based Magnequench was mysteriously sold to members of
former Chinese leader Deng Xiaoping’s family. The facility was then shut down
and moved to China in 2000.
For the fascinating story of how Magnequench and its technology
passed to the Chinese, read a 2006
article by Jeffrey St. Clair. (The connection with the Deng Xiaoping
family was through the Sextant Group, which
purchased Magnequench from GM. Sextant was a front for two Chinese
companies with close ties to the government, which it is believed
targeted Magnequench for developing its long-range cruise
missiles).
Since then, rare earth metals, alloys and magnets needed by US defense
contractors come either directly or indirectly from mostly China, which has a
monopoly on the mining and/or processing of the 17 elements found in the Periodic
Table.
For another great article, on how the US ceded control of its rare earths
industry to China, read our How
the US lost the plot on rare earths
Types
There are six types of permanent magnets, but only two are made with rare
earth elements: neodymium-iron-boron magnets, and samarium-cobalt magnets.
The other four types of magnets are ceramic (or hard ferrite), alnico,
injection molded and flexible.
Without going into a whole lot of detail on these four, ceramic magnets
are composed of iron oxide and barium or strontium carbonate. They are the
earliest type of magnet invented, going back to the ancient Greeks, who knew
about lodestone, a magnetic ore. The first ceramic magnets came out in the
1950s. More powerful magnets than previously, in any shape, could be made by
taking powdered barium ferrite or strontium ferrite and forming it into the
shape of the magnet, then baking it. In contrast neodymium-iron-boron magnets
are an alloy of neodymium, iron and boron, that is melted in a furnace then
cooled into ingots. The ingots are pulverized, the powder is sintered into
dense blocks, heat treated, and cut to shape, before being surface-treated and
magnetized.
Ceramic magnets are easy to magnetize, resistant to corrosion and stronger
than natural magnets, but are brittle and break easily, meaning they can’t be
used in machinery that flexes. Neodymium magnets are also brittle, and are
not as heat-resistant, requiring a coating to prevent
corrosion. However they are stronger than any other type of magnet
of the same size and are very resistant to demagnetization by external
magnetic fields. This makes NdFeBmagnets suitable for powerful turbines
and generators, whereas ceramic magnets are better for lower-power machinery.
Until neodymium-iron-boron and samarium-cobalt magnets came
along, the most powerful magnets were alnico magnets made of aluminium,
nickel and cobalt. Alnico magnets replaced electromagnets, and alnico magnets
have largely been overshadowed by
stronger NdFeB and SmCo magnets, but they are still
placed in high-temperature handling equipment and sensors, to name a couple
of uses.
Injection molded magnets are made by mixing the magnetic material with a
polymer binder. This allows magnets to be molded into complex shapes,
suitable for insertion onto or around existing components, thereby saving
steps in the manufacturing process. Flexible magnets are similar only they
are produced in flat strips and sheets. Vinyl is often used as the binder.
Samarium-cobalt magnets were first introduced in the 1970s. They are
stronger than alnico or ceramic material and offer the best heat resistance
of all the permanent magnet types, with the ability to withstand temperatures
up to 300 degrees C. However due to their higher cost, they are less popular
than the most common rare earth magnet, NdFeB. Samarium-cobalt magnets
are highly resistant to rusting, but they are also brittle and may fracture
when extreme heat causes them to expand.
Neodymium-iron-boron magnets have similar properties to their
samarium-cobalt cousins, except they are less resistant to oxidation, needing
a surface treatment, and can’t withstand such high temperatures. Because they
pack such a high magnetic punch, NdFeB magnets can fit into compact
spaces, such as electric motors and cordless tools.
Terbium and dysprosium are sometimes added to NdFeB magnets to allow them
to tolerate even higher temperatures.
Properties
There are more scientific ways to compare permanent magnets. Remanence
refers to the strength of the magnetic field, coercivity means how resistant
the material is to becoming demagnetized, energy product is the
density of magnetic energy, and Curie temperature is the point at which the
material loses magnetism.
How they work
Electric motors use magnets to convert electrical energy into mechanical
energy. A permanent magnet is placed in a conductive substance, then the
magnetic field from the magnet turns another piece of equipment, which
rapidly rotates the motor. Permanent magnets can also perform the reverse
function, turning mechanical force into electrical force. Placing two
permanent magnets opposite one another creates repellant forces that rotate a
turbine, which then turns a rotating coil called an armature, thereby
generating electricity.
Applications
Since becoming cheaper in the 1990s, neodymium magnets have replaced
earlier alnico and ferrite permanent magnets in a number
of high-tech applications. Common uses include computer hard disk
drives, wind turbine generators, speakers/ headphones, MRI scanners, cordless
tool motors, and motors in hybrid and electric vehicles.
The latter requires a bit more explanation. Internal combustion engines
have a mechanical or hydraulic transmission that is run on gasoline or diesel
fuel. Towards the end of the millennium, vehicles with electric transmissions
were developed, powered by ICEs, batteries or fuel cells. The advantage of an
electric versus a hydraulic or mechanical transmission, is an electric
transmission can charge the battery by regenerating energy through braking.
A permanent magnet motor is considered to be more efficient than
an induction motor based on copper coils - used for example in Tesla’s Model
X and Model 3. A a year ago Tesla
switched to a magnetic motor using neodymium in its Model 3 Long
Range car.
As an aside, neodymium is among a mix of rare earth elements found in the
nickel metal hydride (NiMH) batteries of a range of plug-in electric and hybrid
vehicles, including GM’s EV1, Honda EV Plus, the Ford Ranger EV and the
Toyota Prius.
The anode of a NiMH cell is most commonly a mix of lanthanum, cerium,
neodymium and praseodymium.
The US Military is an important buyer of permanent magnets. Stealth
helicopters have neodymium magnets in their noise cancellation technology
blades.
 
Aircraft use them in their electric motors and actuators, as will the
US Navy’s Zumwalt DDG 1000 guided military destroyer (The ship’s induction
motors generate 58 megawatts of electricity while cruising), hub-mounted
electric traction drives and integrated starter generators. Aircraft
electrical systems employ samarium cobalt permanent magnets to generate
power.
Conclusion
Permanent magnets are a key technology in the massive transformation that
the transportation industry is undergoing, from ICE-powered vehicles to
electrics.
Demand for the materials that go into these magnets is only going to grow.
An example is neodymium. The market for neodymium-iron-boron magnets is
estimated at $11.3 billion; demand for neodymium has increased every year
since 2015. And with electric vehicle sales expected to grow 24% a year until
2030, it’s a valid question whether there’s going to be enough magnet
materials, particularly rare earth elements, to go around.
China has a lock on REE supply and the only significant
non-Chinese supplier is Australia’s Lynas, which processes its REEs in
Malaysia. North America has no rare earth deposits anywhere near production
and only one mine, which ships its rare earths to China for processing.
Read
more about the project and the company’s path to production
Legal Notice / Disclaimer
This document is not and should not be construed as an offer to sell or
the solicitation of an offer to purchase or subscribe for any investment.
Richard Mills has based this document on information obtained from sources he
believes to be reliable but which has not been independently
verified. Richard Mills makes no guarantee, representation or warranty and
accepts no responsibility or liability as
to its accuracy or completeness. Expressions of opinion are those of
Richard Mills only and are subject to change without notice. Richard Mills
assumes no warranty, liability or guarantee for the current relevance,
correctness or completeness of any information provided within this Report
and will not be held liable for the consequence of reliance upon any opinion
or statement contained herein or any omission. Furthermore, I, Richard Mills,
assume no liability for any direct or indirect loss or damage or, in
particular, for lost profit, which you may incur as a result of the use
and existence of the information provided within this Report.
Defense Metals (TSX-V:DEFN), is an advertiser on Richard’s site
aheadoftheherd.com. Richard owns shares of DEFN
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