Magnetic Jewelry Clasp

There are basically two major types of magnets rare earth. The term rare earth is used to refer to the family of lanthanides, which has a very specific meaning in physics. It refers to fifteen elements bearing the atomic numbers sequentially from 57 through 71. This cluster of elements is defined as f-block and by nature has individually incomplete filling. Although in solid state, its condition is unstable because each has basically seven electrons with no pair. As it spins, it causes magnetism unmatched even by ferrites, which used to be the king of magnetism, until these were dethroned in the 1980s when the use for the rare earth variety started gaining ground.

Ferrites are compounds, which are part ceramic, part iron oxide. What makes them inferior to their earthy cousin is first, they are not magnetic enough. Their magnetic prowess is at best, just one third of the competition. In addition, they are more susceptible to being demagnetized. For example, the coercivity (a term used to refer to resistance to demagnetization) of ferrites is 150 on average, which for rare earth is between 600 to 2,000. Thus, if theoretically a government anywhere in the world is to run a bullet train as part of its daily public transit service, using ferrites would be a poor choice. After all, the chance for these magnets being demagnetized is higher and hence, would not be in the best interest of the riding public.

No wonder bullet trains and other mass transit system, roller coasters and high-rise elevators all depend on rare earth magnetism to make things work. However, each of the two types of magnets rare earth has characteristics that make it more suitable for a different industrial application. First, the so-called neodymium variety is more abundant and the magnet of choice of big business because it is simply the strongest magnet on the planet. However, like Superman?s kryptonite Achilles heel, neodymium is more prone to rusting when compared to the rarer samarium-cobalt type. To overcome such weakness, some form of surface coating is done to protect against corrosion.

The samarium-cobalt magnet has its own special weakness as well. It can easily become brittle so manufacturers often enclose it in glass or some other form of casing for protection. It is also more costly both at the production stage and over the counter. Apparently, it has not been able to play catch with the popularity of neodymium. Despite the costs, some industries still favor the use of samarium-cobalt modules because these perform best at high temperatures. The counterpart tends to work better at cooler temperatures. Thus, for a spinning computer hard drive, neodymium will work, but samarium-cobalt can perform much better.

Magnets rare earth are one of the best examples of using the laws of physics to create better products for humanity. Physics genius Albert Einstein might not be entirely happy, being an avowed pacifist, that his most popular formula was used in part to build the first atomic bomb. Nevertheless, if he were alive today, he would probably be pleased to find that the laws of magnetism are being harnessed to prevent accidents on busy cosmopolitan streets.

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