Rare Earth Makes Strong Magnets

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Rare earth magnets are particularly strong magnets made from alloys of elements known as rare earths and certain transition metals, including iron, nickel and cobalt. They were developed in the 20th century and greatly added to the manufacturing abilities of many companies. There are only two primary types of rare earth magnets available today. These are the samarium-cobalt and neodymium varieties. They were developed long after powerful magnets made from iron and other element shad already become standard. They quickly replaced these previous models in many areas of industry and became a vital part of the electronics production process around the world.

History of Rare Earth Magnets
Interest in using rare earths to make powerful magnets began in the 1960’s. The first kind ever developed were known as Samarium cobalt magnets. The alloy of samarium and cobalt made for a particularly strong magnetic field that was quite dense in comparison to that of magnets made from iron or other materials. In addition, these alloys resisted demagnetization and were able to operate at high temperatures. This latter quality was important to improving industrial productivity, since manufacturing processes often involve great heat.
Attempting to make a step forward in the production of strong magnets, researchers were at first disappointed in the otherwise superb neodymium magnet that they developed in the 1980’s. This type of magnet is superior to the samarium cobalt variety in every way except in regard to its Curie temperature. This quality is a statement of how much heat a magnet can withstand before beginning to lose its magnetic properties. The strength of the magnetic field produced by these materials, the density of that field and their ability to resist demagnetization were all superior. However, the neodymium magnet does not withstand great heat very well.
Researchers overcame this weakness by alloying neodymium with terbium or dysprosium. This has ameliorated the tendency to lose magnetic strength sufficiently to make neodymium magnets the hottest selling magnet in industry. These magnets have an additional weakness in that they tend to corrode more rapidly than other varieties. Developers managed ot overcome this drawback just as they did with the low Curie temperature issue. During production, these magnets are coated with nickel, copper or both to prevent corrosion.
Advantages and Disadvantages with Rare Earth Magnets
Humans have derived a lot of good from these strong magnets. They enable people to create a variety of electronic devices and amusing entertainments. However, there are also dangers associated with their strength. Even small versions of these devices can seriously injure a person if they accidentally insert a finger or small limb between two such magnets. There have been cases win which small children have died after swallowing small magnets which later pinched their intestines and caused internal damage.
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Heather Pulse has 11 articles online


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Rare Earth Makes Strong Magnets

This article was published on 2012/02/22