With the development of the society, the application of the magnet is becoming more and more widely, from high-tech products to the most simple packaging, the most widely used or ndfeb strong magnetic and ferrite magnets.
From the development history of permanent magnetic material, the end of the 19th century the use of carbon steel, magnetic energy product (
Measure of permanent magnet magnetic energy storage density quantities)
Less than 1 mgoe (
Mega high Mr)
, and the mass production Nd - abroad
B permanent magnet, magnetic energy product has amounted to more than 50 mgoe.
This century, the material of remanent magnetism Br increase is very small, can improve due to product improvement of coercive force Hc.
And coercive force increase, mainly thanks to the understanding of its nature and high magnetocrystalline anisotropy compounds are found, and the progress of the preparation technology.
At the beginning of the 20th century, people mainly use carbon steel, tungsten, cobalt chromium steel and steel for permanent magnetic material.
Developed in the late 1930 s, AlNiCo permanent magnet materials, makes the large-scale application of permanent magnet material possible.
50 s, the emergence of barium ferrite, reduces the cost of permanent magnets, and to broaden the application scope of permanent magnet materials to high frequency field.
The emergence of cobalt to 60 s, rare earth permanent magnet, is for the application of permanent magnet has opened up a new era.
In 1967, the United States at the university of Dayton Strnat etc. , made by powder method successfully SmCo5 permanent magnets, marks the arrival of the era of rare earth permanent magnet.
So far, ten permanent magnet has experienced the first generation of SmCo5, dilute the second generation Sm2Co17 precipitation hardening type, development to the third generation of Nd -
B permanent magnet materials.
In addition, the history is used as a permanent magnetic material and Cu -
Fe 、 Fe-
Mo 、 Fe-
V, MnBi, A1MnC alloy, etc.
These alloys due to performance is not high, the cost is not low, in most cases has been rarely used.
And AlNiCo, FeCrCo and PtCo alloy is applied in some special occasions.
At present, Ba, Sr ferrite still is one of the biggest amount of permanent magnetic material, but its many applications are being Nd -
Class B material instead.
And now the output value of the rare earth permanent magnet materials have greatly more than ferrite permanent magnet, rare earth permanent magnet magnetic material production, has developed into a large industry size (
Under the condition of the same magnet volume)
: ndfeb, ferrite, samarium cobalt, nickel and cobalt neodymium and ferrite.
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