Introduction to Magnetic Materials
A magnetic material is a material that can react to a magnetic field in a certain way. It is called a magnetic material, and generally consists of a transition element such as iron, cobalt, nickel, and alloys thereof, which can directly or indirectly generate magnetism. Magnetic materials are generally classified into soft magnetic materials and hard magnetic materials according to their ease of magnetization.
The soft magnetic material is relatively easy to magnetize with respect to the permanent magnet material, and is also prone to demagnetization. Its main function is the transformation and transmission of magnetic conduction and electromagnetic energy. Such materials require high magnetic permeability and magnetic induction, while the area or magnetic loss of the hysteresis loop is small. The smaller the residual magnetic induction and coercive force, the better, and the larger the saturation magnetic induction, the better.
Magnetic Materials
Permanent magnet materials, also known as hard magnetic materials, are magnetized after an external magnetic field, which still retains high residual magnetism for a long period of time, and can maintain one or most of the original magnetization direction under the action of a relatively large reverse magnetic field. Magnetic material. The requirements for such materials are high residual magnetic induction, strong internal coercivity, and large magnetic energy product. Permanent magnet materials can be used for important functions such as electrical signal conversion and electrical/mechanical energy transmission, and are widely used in energy, transportation, machinery, medical, computer and home appliances.
According to the characteristics of composition and magnetic properties, permanent magnet materials can be divided into three categories: rare earth permanent magnet materials, ferrite permanent magnet materials and other permanent magnet materials. Among them, rare earth permanent magnet materials are represented by NdFeB permanent magnet materials.
The rare earth permanent magnet material is a third generation permanent magnet material successfully developed after the metal system and the ferrite system. Since the advent of the rare earth permanent magnet materials in the 1960s, they have been developing at a high speed. According to the time sequence of their development and application, they can be divided into four generations: the first generation is SmCo5 series materials; the second generation is Sm2Co17 series magnets; the third generation rare earth permanent magnets are The NdFeB magnetic material, which was successfully developed in the early 1980s, quickly replaced the Sm2Co17 magnet in many fields due to its excellent performance and low price, and soon realized industrial production. The fourth generation is rare earth. Iron nitrogen (Re-Fe-N system) and rare earth iron carbon (Re-Fe-C system). According to industry experts, it is at least a few decades for the fourth-generation rare earth permanent magnet materials that are expected to be mature to become mature.
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