Sintered NdFeB magnets VS bonded NdFeB magnets
NdFeB magnets are divided into sintered and bonded NdFeB magnets according to the manufacturing process. Below we analyze the difference between sintered NdFeB magnet and bonded NdFeB magnet.
Bonded neodymium iron boron is made of NdFeB magnetic powder added to the binder;
Sintered neodymium iron boron adopts powder metallurgy technology, and the smelted alloy is made into powder and pressed in a magnetic field.
Bonded magnets are isotropic, that is, regardless of magnetization in any direction, the magnetic field strength is the same (also related to the shape).
Sintered magnets are anisotropic. In the production process of sintered magnets, there is a process called magnetic field orientation. When magnetizing, it can only be magnetized along the orientation direction to have high magnetic field strength. There is no magnetism.
Theoretically speaking, the isotropic remanence is one-half of the anisotropic remanence. Since the magnetic energy product is proportional to the square of the remanence, the isotropic magnetic performance is only a quarter of the anisotropic magnetic performance. one.
Bonded NdFeB magnets contain adhesives, and their density is generally only 80% of the theoretical density, usually 6g/cm³. Therefore, the magnetic properties of the bonded magnets will be attenuated by about 30%.
The density of sintered NdFeB magnet is basically close to the theoretical density, usually 7.5g/cm³, with little attenuation.
Taken together, the magnetic properties of bonded NdFeB magnets are only about one-fifth of sintered magnets.
At present, the magnetic energy product of sintered NdFeB magnets can reach more than 50M, while bonded magnets are generally below 10M, and the best is only 12M.
The performance of the magnetic powder used in the bonded magnet is generally 15M, and it is only 10.5M after being made into the bonded magnet.
Sintered NdFeB magnets are relatively brittle and difficult to process into various complex shapes.
Bonded NdFeB can be formed at one time without secondary processing and can be made into various complex shapes.
Bonded NdFeB magnets are much cheaper than sintered NdFeB magnets.
Bonded NdFeB magnet has strong oxidation resistance and does not require surface treatment. Sintered NdFeB magnets are easy to oxidize and require surface treatment for electroplating or coating.