1. Curie temperature
Curie temperature（TC）, also known as Curie point and magnetic transition point. It refers to the temperature at which the spontaneous magnetization in magnetic materials drops to zero, and is the critical point at which ferromagnetic or ferrimagnetic substances transform into paramagnetic substances. Below the Curie point temperature, the material becomes a ferromagnet, and the magnetic field associated with the material is difficult to change. When the temperature is above the Curie point, the substance becomes a paramagnet, and the magnet’s magnetic field changes easily with changes in the surrounding magnetic field.
The Curie point is determined by the chemical composition and crystal structure of the substance. If the temperature reaches the Curie temperature, the molecules inside the magnet move violently and demagnetize, which is irreversible.
The Curie temperature is named after French physicist Pierre Curie, who discovered in his laboratory that magnetic materials lose their magnetism when magnets are heated to a certain temperature.
2. Working temperature
In fact, the Curie temperature is only the temperature under laboratory conditions, or it can be said to be the ideal temperature. The working temperature of the magnet is the highest temperature at which the material can maintain magnetism under actual circumstances. The maximum operating temperature of sintered NdFeB is much lower than its Curie temperature. Within the operating temperature, the magnetic force will decrease as the temperature increases, but most of the magnetic force will recover after cooling.
The relationship between working temperature and Curie temperature: The higher the Curie temperature, the higher the working temperature of magnetic materials, and the better the temperature stability. Adding cobalt, terbium, dysprosium and other elements to the sintered NdFeB raw material can increase its Curie temperature.
The maximum operating temperature of sintered NdFeB depends on its own magnetic properties and the selection of the working point. For the same sintered NdFeB magnet, the closer the working magnetic circuit is, the higher the maximum operating temperature of the magnet is, and the more stable the performance of the magnet is. Therefore, the maximum operating temperature of the magnet is not a definite value, but changes with the degree of closure of the magnetic circuit.
|Performance level||Working temperature||Curie temperature|
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