Types Of Rare Earth Magnets

Rare earth magnets have revolutionized the world of magnetics in the last few decades. Their development began in the 1970’s. Scientists first made these special permanent magnets with alloys composed of rare earth elements. They are significantly stronger than regular, ferrite magnets. Industry has put them to use for various tasks, such as in rare earth disc magnets. However, there are some weaknesses in these magnets to which their makers must adapt. The materials used to make them are also, as the name implies, very rare and this causes supply concerns.

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These magnets are not made purely from rare elements. Such elements demonstrate their magnetism only at temperatures well below room temperature, limiting their usefulness. However, they are easily made into alloys with ferromagnetic materials which exhibit magnetism at temperatures above room temperature. These alloys function well because they have high levels of magnetic anisotropy. They can be magnetized in only one direction. The force of their magnetism remains strong in that one direction, making them far more useful and versatile than magnets previously used for industrial purposes.

These magnets are made from two different compositions. One of these compositions is the samarium-cobalt magnet. The first such magnets were all made from this alloy. It was also these magnets which demonstrated the weakness common to all types of this new magnet. They are extremely brittle and often fracture when exposed to thermal shock. Still, the value of these alloys could not be denied and soon industries were making various permanent magnets and rare earth disc magnets from samarium-cobalt.

A new kind of magnet was invented in the 1980’s. These new magnets were made with neodymium, iron and born. Neodymium magnets are superior to samarium-cobalt magnets due to their much stronger magnetic field strength. However, they are also less able to resist oxidation than samarium cobalt and they function well only at lower temperatures. However, the first weakness was overcome by using special coatings to protect the magnets from corrosion. The second weakness was only overcome by the lower cost of neodymium magnets. Their inexpensiveness, combined with their higher strength, soon gave them first place among magnets. Most computer hard drives use neodymium magnets now. An increasing number of toys are also built each year incorporating neodymium magnets into their structure.

The number of applications for rare earth magnets increases every year. Rare earth disc magnets and various permanent magnets all experience widespread use in industry. Developers are also finding new ways to use them in entertainment and medicine. The famous magnetic levitation transport trains in Europe manage their incredible speeds due to the power of these magnetic alloys which have come to replace regular magnets in a surprising number of ways.

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