A Complete Guide to Permanent Magnetic Materials: Classification Analysis and Application Scenarios

We usually divide magnetic materials into hard magnetic materials and soft magnetic materials.

Hard magnetic materials are also known as permanent magnetic materials. After being magnetized in a magnetic field, permanent magnetic materials can maintain a high residual magnetism even when the field is removed. In contrast, soft magnetic materials can be easily magnetized in a magnetic field and also easily demagnetized once the field is removed.

Soft magnetic materials are characterized by low residual magnetism, low coercivity (<80 A/m), easy magnetization, and easy demagnetization. In comparison, permanent magnetic materials have high residual magnetism, high coercivity (>4000 A/m), and are difficult to magnetize and demagnetize.

Today, we will discuss the classification of permanent magnetic materials. Based on their primary components, they can be divided into the following categories:

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• AlNiCo Permanent Magnets: Composed mainly of iron, nickel, and aluminum, with the addition of elements like copper, cobalt, and titanium, these magnets feature high residual magnetism, low temperature coefficient, and strong temperature resistance. They are typically used in instruments, telecommunications, and magnetic switches where temperature stability is essential.

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• Ferrite Permanent Magnets: Based on different production processes, they can be further divided into sintered ferrite, bonded ferrite, and injection-molded ferrite. Sintered ferrite mainly includes BaFe12O19/SrFe12O19, known for its strong oxidation resistance and low cost. These magnets are primarily used in telecommunications, electrical instruments, control devices, and industrial equipment where moderate performance, compact size, and low cost are required.

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• SmCo Permanent Magnets: Composed of intermetallic compounds of samarium and cobalt, including SmCo? and Sm?Co??, these magnets have strong corrosion and oxidation resistance and can withstand high temperatures. They are mainly used in aerospace applications, where high performance, high-temperature stability, and resistance to high temperatures are critical, with cost being a secondary concern.

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• NdFeB Permanent Magnets: Made from neodymium, iron, and boron, these magnets are further divided into sintered NdFeB, bonded NdFeB, and injection-molded NdFeB based on the production process. They have extremely high magnetic energy product and coercivity but are prone to oxidation and have relatively low temperature resistance. They are mainly used in electric vehicles and wind power generation, where high performance and compact size are required.

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