Neodymium magnet

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Neodymium magnet

The neodymium magnet which is used for the head drive of the HDD

One of the rare earth magnets (rare earth elements magnet) composed primarily of neodymium, iron, boron with the neodymium magnet (a neodymium magnet, English: Neodymium magnet). I am considered that it is the strongest among the permanent magnets. Was invented in 1984 by 佐川眞人 and others of American General Motors and Japanese Sumitomo Special Metals (existing Hitachi Metals) [¹]; [²]. The main aspect is Nd₂Fe₁₄B.

I may be called "a neodymium magnet", but these are the same, and I am controversial, but "a neodymium magnet" is assumed a right name in Japan (I refer to the step of the name of the neodymium item).

Table of contents

Characteristic

Miscellaneous contents are enumerated by this gnarl. I incorporate it as the text, or, as for the gnarl which only enumerated matters by items, it is necessary to be eliminated rearranging. (March, 2012)

• Magnetic induction is high and has very strong magnetic force.
• It is fragile mechanically, and a magnetic temperature change is big.
• It is easy to produce heat demagnetization when I heat up. Coercive force improves when I add dysprosium. I am told that heat demagnetization is improved 15 degrees Celsius by addition of 1% of dysprosium.
• Because it is easy to be rusted, it is often plated with nickel.
• The Curie point is approximately 310 degrees.
• A class charge account is done in magnetic strength from N24 to N54. The number after N expresses magnetic strength, but it is said that it is possible theoretically to N64.

including the use

Magnetic force is very strong, and the range of the used product is wide from small size to large size. The small example is a hard disk drive and a CD Player, a cell-phone. The large-scale example is a field magnet of the permanent magnet synchronous motors for a train, the hybrid car elevator drive. With the hard disk drive, I am used for an actuator to move the reading and writing device called the head. It is said that a tight low tone appears because I can adopt a harder damper and is used for most of the driver of recent headphones. Because a strong magnetic field is provided even if I lower size, it is the magnet which is indispensable to particularly small inner ear type, canal type headphones.

A study to improve heat demagnetization is performed by lowering the crystal particle size of the neodymium magnet because above-mentioned dysprosium is a particularly rare resource without using dysprosium recently. However, it may self-ignite because air and surface area to mention increase when reactivity with oxygen is strong, and neodymium makes the crystal grain of the magnet small. Therefore, it is necessary to perform the magnet production in a state to the exclusion of oxygen. In addition, because I include a lot of iron, it is easy to be rusted very much and uses it after coating it with nickel when I am used as a product.

Because there is adsorption power more than 10kgf with the size of number cm, it is necessary to wear gloves not to catch a finger when I treat it.

In October, 2014, TDK succeeded in the development of the magnet which reduced content of neodymium to conventional half [³].

Footnote

1. ^ M. Sagawa; et al. (1984). "Permanent Magnet Materials based on the Rare Earth-Iron-Boron Tetragonal Compounds (Invited)." IEEE Transactions on Magneticsw MAG-20 (5): 1584-1589. NAID 80002298568. 
2. ^ 佐川眞人, Masaaki Hamano, 平林眞編 "a permanent magnet is materials science and application" アグネ technology center, 2007. ISBN 978-4 - 901,496-38-4。
3. The ^ "TDK high-performance magnet development that was reduced to half with neodymium content." The Nihon Keizai Shimbun. (October 4, 2014). http://www.nikkei.com/article/DGXMZO77909700T01C14A0000000/ October 20, 2015 reading. 

Allied item

Wiki media Commons has a category in conjunction with Neodymium-iron-boron magnet.

• Magnet
• Permanent magnet
• Rare earth magnet

Outside link

• 佐川眞人 (public interest international technology foundation Foundation)

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