Development history of permanent magnet materials

Development history of permanent magnet materials

Japan’s T.mishima discovered the first generation of magnet materials

It is mostly used in the instrument industry, magnetoelectric instruments, micro-motor relays, etc. Carbon steel, tungsten steel and chrome steel with low magnetic energy product are mainly used.
At the end of the 19th century, people mainly used carbon steel, tungsten steel, chromium steel and cobalt steel as permanent magnet materials. , the magnetic energy product (BH) max (a physical quantity that measures the density of magnetic energy stored in a permanent magnet) is less than 1MGOe (megagao Austria).

Metal permanent magnet material:

Bar Magnet showing magnetic field w iron filings. studio.

It mainly includes two types of permanent magnet alloys, Al-Ni-Co and Fe-Cr-Co. The magnetic energy product of this type of material is low, but its Curie temperature is high, the temperature stability is good, and the temperature coefficient of magnetic induction is low, so the use in some special devices cannot be replaced, and there is still a certain market demand.


Ferrite permanent magnet:

Also known as permanent magnet ferrite, it is processed by a compound of Fe2O3 and strontium (or barium, etc.) in a certain proportion. Its raw materials are cheap, the process is simple and the price is low, so it developed rapidly in the 1970s. In addition, its high resistivity makes it especially suitable for applications in high frequency and microwave fields. Cost reduction, widening the application range to high-frequency fields • Began to be used as motor materials in end consumer products such as automobiles, home appliances, and consumer electronics

Rare earth permanent magnet materials:

Samarium cobalt permanent magnets were discovered by StrNar in the United States, and NdFeB permanent magnets were discovered by sagawa in Japan. • Mostly used in microwave communications, motors, computers, automation, magnetic medicine and other industries
A class of high-performance permanent magnet materials based on intermetallic compounds formed by rare earth elements (Sm, Nd, Pr, etc.) and transition metal elements TM (Fe, Co, etc.). The development of rare earth permanent magnet materials has gone through three generations, the first generation of SmCo5, the second generation of Sm2Co17 and the third generation of NdFeB.

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