A brief introduction to NdFeB (neodymium) magnet, “the magnet king”

A brief introduction to NdFeB (neodymium) magnet, “the magnet king”

NdFeB (neodymium magnet), simply speaking, is a kind of magnet, but unlike most of the magnets we see, it’s called “the magnet king” because of its excellent magnetic properties. NdFeB are praseodymium metal, boron iron and other alloys, it is also called magnetic steel. NdFeB contains a large amount of rare earth element neodymium, iron and boron to form the Nd2Fe14B tetragonal crystalline structure. so it is hard and brittle in character.

Molecular structure

Characteristics

Because the surface is easy to be oxidized corrosion, NdFe must be coated on the surface. Surface chemical passivation is one of the best solutions. As a kind of rare earth permanent magnet, NdFeB has the advantages of extremely high magnetic energy product, high coercive force, and high energy density at the same time, which is widely used in modern industry and electronic technology. So NdFeB makes it possible for the instruments and meters, electronic motor, magnetization of the magnetic separation equipment to be minimized, lightweighted, thinned.

Applications

Neodymium magnets have replaced alnico and ferrite magnets in many of the myriad applications in modern technology where strong permanent magnets are required, because their greater strength allows the use of smaller, lighter magnets for a given application. Some examples are:

• Head actuators for computer hard disks
• Mechanical e-cigarette firing switches
• Locks for doors
• Loudspeakers and headphones
• Mobile phone speakers, taptic feedback and auto focus actuators
• Magnetic bearings and couplings
• Benchtop NMR spectrometers
  • Electric motors: (Using neodymium magnets in electric motors can reduce their power consumption by half.)
  • Cordless tools
  • Servomotors
  • Lifting and compressor motors
  • Synchronous motors
  • Spindle and stepper motors
  • Electrical power steering
  • Drive motors for hybrid and electric vehicles. The electric motors of each Toyota Prius require one kilogram (2.2 lb) of neodymium.
• Actuators
• Electric generators for wind turbines (only those with permanent magnet excitation)
• Alignment of nanocellulose chiral nematic suspensions to fabricate cellulose nanocrystals films with tuneable specular and off-specular optical response
• Voice coil
• Retail media case decouplers[clarification needed]
• In process industries, powerful neodymium magnets are used to catch foreign bodies and protect product and processes

Grades

Neodymium magnets are graded according to their maximum energy product, which relates to the magnetic flux output per unit volume. Higher values indicate stronger magnets. For sintered NdFeB magnets, there is a widely recognized international classification. Their values range from 28 up to 52. The first letter N before the values is short for neodymium, meaning sintered NdFeB magnets. Letters following the values indicate intrinsic coercivity and maximum operating temperatures (positively correlated with the Curie temperature), which range from default (up to 80 ℃ or 176 ℉) to AH (230℃ or 446 ℉).

Grades of sintered NdFeB magnets:

N30 – N52

N30M – N50M

N30H – N50H

N30SH – N48SH

N30UH – N42UH

N28EH – N40EH

N28AH – N35AH

Magnetic properties of various grades of NdFeB materials

The largest deposit and reserve of rare earth is in Bayan’obo mine, Inner Mondolia, China.  Baotou bayan’obo mine is the largest rare earth mine in the world.