During the 70s and 80s, humanity created one of the strongest types of magnets by mixing alloys of rare elements found without our earth. These magnets were called rare earth magnets and they have superior properties than those magnets made out of ferrite or alnico.
Rare earth magnets surpass others in multiple areas, but the most important one is the magnetic field. The magnetic field of rare earth magnets can be up to 3 times stronger than other magnets. The usual magnetic field exceeds 1.4 teslas, whereas other types of magnets are usually between 0.5 and 0.9 and in the least cases, 1 Tesla.
What Are The Types of Rare Earth Magnets?
In nature, there are two types of materials of which rare earth magnets are created from. Neodymium and Samarium-cobalt are the two types of allows that give these magnets such strong proportions.
Invented in the 1980s, neodymium magnets are considered to be the strongest and most affordable type of rare earth magnet ever created. Since these magnets are highly susceptible to corrosion, they are usually plated or coated. Neodymium magnets are made out of an alloy of neodymium, whereas iron and boron are used to give the magnet its much-needed protection from corrosion, breaking, chipping, or crumbling. These magnets have the highest magnetic field strength and they are more magnetically stable, which is an ability called coercivity. However, they are not perfect as they have a lower Curie temperature and are more susceptible to oxidation. We mentioned corrosion, and neodymium magnets are also vulnerable to it. That is why neodymium magnets use zinc, gold, nickel, or tin as a protective layer that prevents corrosion.
According to AOMAG, samarium-cobalt magnets were the first ones created in the family of rare earth magnets. While they are far less used than neodymium magnets, they have a higher Curie temperature. Samarium-cobalt magnets come at a higher cost and lower magnetic strength, but they have become a niche magnet for applications where a high field of strength is needed to operate in high temperatures. One thing that samarium-cobalt magnets have over neodymium is that they are highly resistant to oxidation, but are more susceptible to chipping, cracking, and fracturing when subjected to thermal shock.
Common Applications and Use of Rare Earth Magnets
Neodymium magnets are far more used in applications than samarium-cobalt magnets. Since their introduction to the general public in the 1990s, neodymium magnets have had huge success in various fields and applications. Some of the most common applications where neodymium magnets are used in are:
- Computer Hard Disk Drives
- MRI scanners
- Speakers and headphones
- Generators for wind turbines
- Bicycle dynamos
- Permanent magnetic motors in cordless tools
- AC servo motors
- Fishing reel brakes
- High use in electric and hybrid vehicles as traction motors and integrated starter-generators
- Mechanically powered flashlights
- High industrial use as a way of maintaining product purity, equipment protection, and control
- They can be used for the capture of fine metallic particles in lubricating oils
There are also other uses of rare earth magnets that are considered outside the realms of common practice and use. Those are:
- Linear motors
- Stop motion animation
- Diamagnetic levitation experimentation
- Electrodynamic bearings
- LED Throwies
- Magnet toys
- Electric guitar pickups and more