The Difference between Maximum Working Temperature and the Curie Temperature

Magnet consumers are often confused the definitions of Max. Working Temperature Tw and the Curie Temperature Tw of the permanent magnet. In reality, Max. Working Temperature and the Curie Temperature Tc are two totally different conceptions.

Magnetism behavior of material can be classified into ferromagnetism, ferritemagnetism, anti-ferromagnetism, paramagnetism, and diamagnetism, then permanent magnet is definitely belongs to the ferromagnetc material. For ferromagnetic material, thermal oscillation of internal elementary particles will be aggravated with increasing temperature, then alignment of micro magnetic dipole moment inside the permanent magnetic material gradually disorder. Thereby, magnetic polarization J declines with increasing temperature in macroscopic. Magnetic polarization J will further drop to zero once the temperature exceeds a certain temperature, then permanent magnetic material transforms into paraferromagnetism state and basically lost their magnetism. The transition temperature between ferromagnetism and paramagnetism is generally known as Curie Temperature or Curie point.

Magnetism type Ferromagnetism Ferrimagnetism Anti-ferromagnetism Paramagnetism Diamagnetism
Magnetism behavior Atoms have parallel aligned magnetic moments. Atoms have anti-parallel aligned magnetic moments. Atoms have mixed parallel and anti-parallel aligned magnetic moments. Atoms have randomly oriented magnetic moments. Atoms have no magnetic moment.
Ferromagnetism-Curie Temperature Ferrimagnetism-Curie Temperature Anti-ferromagnetism Paramagnetism Diamagnetism
Typical material

Fe, Co, Ni, Gd, Tb, Dy element, and their alloys or intermetallic compounds, such as FeSi, NiFe, CoFe, SmCo, NdFeB, CoCr, and CoPt.

Various ferrite material. Intermetallic compounds composed of heavy rare earth elements and Iron or Cobalt, such as TbFe.

3d transition metals Cr and Mn. Rare earth elements Nd, Sm, Eu. Some alloys and compounds like MnO and MnF2.

O2, Pt, Rh, Pd, Be, Mg, Ca.

Cu, Ag, Au.

C, Si, Ge, α-Sn.

N, P, As, Sb, Bi.

S, Te, Se.

Fe, Cl, Br, I.

He, Ne, Ar, Kr, Xe, Rn.

Max. Working Temperature, also referred as the Max. Operating Temperature, is a specific temperature that magnetic performance of permanent magnetic material reduces a certain extent in comparison with room temperature. Max. Working Temperature of the permanent magnet is considerably lower than its Curie Temperature. Take sintered Neodymium magnet as an example, either Max. Working Temperature or Curie Temperature can be significantly enhanced by adding Cobalt (Co), Gallium (Ga), and heavy rare earth elements Dysprosium (Dy) or Terbium (Tb). Beside Curie Temperature, Max. Working Temperature of every permanent magnetic material is also influenced by its intrinsic coercivity, working status in the magnetic circuit. The same magnet has completely different Max. Working Temperature under different applications.

Material type Magnet type Max. Operating Temperature Tw

(degrees Celsius)

Curie Temperature Tc

(degrees Celsius)

Sintered Neodymium Magnet N series 80 310
M series 100 340
H series 120 340
SH series 150 340
UH series 180 350
EH series 200 350
AH series 230 350
Sintered Samarium Cobalt Magnet SmCo5 magnet 250-300 750
Sm2Co17 magnet 250-550 800-840
AlNiCo Magnet Sintered AlNiCo Magnet 450 810-860
Cast AlNiCo Magnet 450-550 760-860
Ferrite Magnet Sintered Ferrite Magnet 250 450

3 comments

  1. Prezados senhores,
    Estou desenvolvendo uma nova versão do motor stirling ( motor de combustão externa que pode ser movido por qualquer combustível). No meu projeto , ha necessidade do uso de ímãs que operam em altas temperaturas. Ainda não tenho esses valores , Apenas a título de exemplo, a chama da da queima do GLP, pode atingir até 600 graus célcios. Acredito que, no interior do motor, a temperatura seja bem menor que esta.
    Estou montando um protótipo, cujo cilindro tem 65mm de diâmetro interno e 110 de comprimento (camisa de motor de motocicleta). Concordo que essas informações estão ainda muito precárias, mas se vocês tiverem alguma ideia que possa me ajudar, ficaria grato em recebe-la.
    Att. Rolim
    Rolim

    Reply
  2. Hematita tem uma temperatura de curie de 680 graus Celsius, outro mineral que pode ser utilizado é a Maghemita que possui Tc a 750 graus Celsius.

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  3. […] بعلاوه، همه مواد مغناطیسی دارای آستانه‌ای معروف به «Curie temperature» هستند، که دمایی را نشان می‌دهد که در آن تحریک حرارتی […]

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