Permanent magnetic materials, also known as hard magnetic materials, are materials that still have magnetism after the magnetization field is removed. Soft magnetic materials have strong magnetic induction strength when the magnetization field exists, and lose magnetism when the magnetization field is removed. Hard and soft here do not mean hard and soft in mechanical properties, but in magnetic properties. Hard magnetism means that a magnetic material can retain its strong magnetism (magnetism for short) for a long time after being magnetized by an external magnetic field, and is characterized by strong coercivity. Coercivity is the magnetic field strength that makes magnetized materials undergo demagnetization and reduce the residual magnetism (residual magnetic flux density or residual magnetization) to zero.
At present, the application market of magnetic materials products in China is expanding rapidly. Magnetic materials matching components are increasingly demanded in the domestic market. In accordance with the requirements of environmental protection, oil-free automobiles and motorcycles are the direction of future development, which will bring a broad market to the development of rare earth permanent magnets. "Green Lighting Project" is also a major energy-saving project in our country. The development of energy-saving lamps requires the use of a large number of high-end ferrite soft magnetic cores and anti-interference magnetic cores.
With the increasing number of car production and speakers used, the demand for ferrite permanent magnet materials is also increasing. The development of computers has driven the development of related supporting components. Magnetic disks, optical disk drives and printer drive heads are the largest "users" of NdFeB. Multimedia acoustics also demands permanent magnetic materials (hard magnetic materials
) in a large amount.