Curie Temperature of Permanent Magnets

Regarding the Curie temperature of permanent magnets, many people will ask whether the Curie temperature of magnets is the highest working temperature of magnets.

We Baidu this sentence, found that there are two distinct replies, one is a positive response, the other is the opposite, then in the end Curie temperature is not the highest working temperature of magnets?

Let’s first take a look at Curie’s temperature.

Curie temperature is the temperature at which a material can change between a ferromagnet and a paramagnet. The material becomes a ferromagnet below Curie temperature, and the magnetic field associated with the material is difficult to change. When the temperature is higher than Curie temperature, the material becomes paramagnet, and the magnetic field of the magnet can easily change with the change of the surrounding magnetic field.

What are the Curie temperatures of common ferrites, Nd-Fe-B, Al-Ni-Co?
It is reported that the Curie temperature of ferrite is about 450 C, that of NdFeB magnet is 320-380 C, and that of Al-Ni-Co is 860-900 C.

Curie Temperature of Permanent Magnets

Curie Temperature of Permanent Magnets

What’s their working temperature?

The working temperature of ferrite magnet is 80-100 C, the high temperature resistant type can reach 350 C, the working temperature of NdFeB magnet is 80-220 C, the working temperature of samarium-cobalt magnet is 250-350 C, and the working temperature of Al-Ni-Co magnet is 450-900 C.

Working temperature means that the magnetic force will decrease when the temperature rises in this temperature range, but will recover after cooling. Each magnet has the highest working temperature, and the magnetic properties will drop sharply when exceeding this temperature, and even if returned to normal temperature, the faded magnetism will not recover.

What does the height of the Curie point relate to?

The Curie point is related to the crystal structure formed by the magnet sintering, the impurities inside, the cooling environment, the composition ratio of the alloy, as well as the specific sintering process, batching → smelting ingot → making powder → pressing → sintering tempering → magnetic detection → grinding → cutting → electroplating → finished product. Among them, batching is the foundation and sintering and tempering is the key.

Conclusion

The Curie temperature of the magnet is not the highest working temperature of the magnet. At Curie temperature, the magnetism of the magnet will disappear completely. Each magnet has the highest working temperature, beyond which the magnetic properties will drop dramatically, and even if it returns to normal temperature, the faded magnetism will not be restored.

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