Scientists Break New Ground with Rare Earth-Free Magnets for Industrial Motors
Step onto any factory floor or industrial plant, and you’ll hear the rhythmic hum of machinery powered by industrial motors. While most of these workhorses rely on induction motor technology, there’s a growing shift toward permanent magnet motors.
These motors are prized for their superior efficiency and long-term cost savings, especially in industries where equipment runs non-stop. But there’s a catch: the magnets currently used are packed with rare earth materials, making them expensive and highly susceptible to supply chain disruptions.
Globally, industries are feeling the pinch. Rare earth elements, while essential in many high-tech and industrial applications, come with their fair share of problems. From skyrocketing costs to geopolitical dependencies, these materials pose serious economic and environmental challenges. It’s no wonder that scientists and engineers have been scouring the periodic table for alternatives that are both affordable and scalable.
Cracking the Code of Magnet Performance
Finding a magnet that doesn’t rely on rare earth elements isn’t just a matter of mixing the right ingredients. These magnets need to perform under extreme conditions. High temperatures, magnetic interference, and mechanical stress are all in a day’s work for industrial motors.
Central to a magnet’s reliability is a property known as coercivity. Simply put, coercivity measures a magnet’s resistance to losing its magnetic properties when exposed to external magnetic fields or high temperatures. Industrial motors often operate at temperatures that would make most magnets wave the white flag. A viable solution, therefore, needs to maintain coercivity even when the heat is on.
A Rare Earth-Free Revolution
Enter the team at the U.S. Department of Energy’s Ames National Laboratory, led by scientist Jun Cui. Their mission: develop a cost-effective, high-performance magnet without touching the rare earth supply chain. What they’ve achieved could be a game-changer.
The team’s innovation centres around a bonded magnet made from manganese and bismuth, commonly referred to as MnBi. The standout feature of this magnet is its ability to double its coercivity with just a 100°C (212°F) increase from room temperature. This makes it ideal for the high-heat environments of industrial motors.
Cui emphasised the broader implications of their breakthrough: “You cannot use rare earths to solve everything. That’s an awful waste of a critical natural resource,” he explained.
The Secret Lies in the Process
So, what makes the MnBi magnet so special? According to Cui, it all boils down to the manufacturing process. Magnets have microscopic structures called grains, and how these grains interact can make or break magnetic performance.
“We don’t want those grains to touch each other,” Cui noted. “If they touch, they will establish some sort of a communication, and it takes only one imperfect grain to convince the whole neighbourhood and create an avalanche-loss of magnetism.”
To tackle this, the team developed a meticulous process to isolate these grains. First, they reduce the material to a fine powder. Then, each particle is coated with a delicate polymer solution to prevent grain-to-grain contact. During fabrication, the particles are aligned using an external magnetic field, resulting in an anisotropic magnet with a preferred direction of magnetisation. This alignment boosts the magnet’s overall performance, according to Ames Lab scientist Wei Tang.
Economic and Environmental Wins
One of the standout features of the MnBi magnet is its use of bismuth. This element is not only naturally abundant but also a byproduct of smelting and refining other materials. Cui highlighted the benefits: “Utilising a byproduct contributes to cost saving and resource efficiency for this material, making it an economical choice.”
While the team did have to compromise on some magnetic force to achieve high coercivity, this trade-off suits the needs of many industrial applications perfectly. As Cui pointed out: “If we look at the whole world right now, actually, motors can operate without magnets. But on the other side, high efficiency motors require high-performance magnets. We are developing something in between, and offering a balanced solution: an affordable, non-rare-earth magnet for targeted industrial tasks.”
From Lab to Factory Floor
What’s even more exciting is that the research isn’t just gathering dust on a laboratory shelf. The team has already partnered with industry players to test the MnBi magnet in real-world applications. One such collaboration involved an industrial pump motor, which not only met but slightly exceeded design specifications.
The testing phase has now advanced to endurance or “fatigue tests,” where the magnet’s long-term performance is being scrutinised. Tang shared his enthusiasm: “I am excited because we’re doing lots of research, and some research just gets published in a paper. But this magnet is non-rare earth, which is very significant. And we are very close to achieving real-world applications for this magnet. If successful, this would be the first in the world for industrial application of the non-rare-earth MnBi magnet.”
A Glimpse into the Future
The team at Ames National Laboratory, operated by Iowa State University and supported by the U.S. Department of Energy, is setting the stage for a new chapter in industrial motor design. Their work not only tackles the technical challenges of magnet performance but also addresses the economic and environmental costs associated with rare earth materials.
Cui summed up the team’s motivation perfectly: “As a scientist, the ultimate reward is seeing your work make a real-world impact.”
Powering Tomorrow’s Industry, Sustainably
As industries worldwide grapple with the twin challenges of energy efficiency and resource scarcity, innovations like the MnBi magnet couldn’t come at a better time. By eliminating the need for rare earth elements, this breakthrough offers a more sustainable, cost-effective path forward for manufacturers everywhere.
With real-world testing already underway and promising results on the horizon, it’s only a matter of time before these rare earth-free magnets find their place in factories, plants, and industries across the globe.
