NdFeB magnets known as Neodymium-Iron-Boron, Neodymium, Neo, NIB or Rare Earth Neodymium magnets, are the third generation of rare earth permanent magnets. They have been available for industrial use since 1984. According to the difference between the production technologies, NdFeB can be divided into bonded NdFeB and sintered NdFeB, but we are only specialized in sintered NdFeB.
Almost all Sintered NdFeB magnets are anisotropic and can only be magnetized in the orientation direction. In general, magnetizing fields of about 30 kOe are required to saturate NdFeB magnets, and 40 kOe required for high coercivity grades.
They offer the highest energy product of any material today and are available in a very wide range of shapes, sizes and grades. These qualities have made NdFeB magnets preferable over the commonly used larger and less powerful Ferrite magnets.
Although the Curie temperature for NdFeB materials is 310-370ºC, some irreversible loss of output may be expected at even moderate temperatures. NdFeB magnets also have a moderately high reversible temperature coefficient of Br which reduces total magnetic output as temperature rises. Selection of NdFeB instead of SmCo, for example, is a function of the maximum temperature of the application, required magnetic output at typical use temperature and total cost of the system.
However, they are sensitive to oxidization and can develop corrosion, so they require surface protection like phosphate, passivation, Ni, NiCuNi, Zn, Epoxy, NiCuNi+Sn or others.
Characteristics
.Outstanding magnetic properties – Br high to 14.5 kG (1. 45T) and (BH)max high to 52 MGOe (414 kJ/m3)
.High demagnetization resistance –maximum Hcj higher than 35 kOe (2785 kA/m)
.High working temperature – maximum working temperature high to 230ºC
.Wide range of grades with new ones regularly being developed – High magnetic properties, AH grades or Low Weight Loss materials and so on.
Applications
Due to their characteristics above, NdFeB are the ideal magnetic material in following applications, particularly where high powered magnets are required, size and weight reduction needed to be considered:
.Speakers
.Magnetron Sputtering Cathodes
.Sensors
.Wind Turbines
.Servo Motors
.Traction Motors
.Voice Coil Motors
.MRI
.Magnetic Separators
.Toys
.Magnetic Assemblies or Magnetic Systems
Physical Properties
Characteristics |
Reversible Temperature Coefficient 20-150ºC, α(Br) |
Reversible Temperature Coefficient 20-150ºC, β(Hcj) |
Coefficient of Thermal Expansion |
Thermal Conductivity |
Specific Heat |
Curie Temperature |
Flexural Strength |
Density |
Hardness, Vickers |
Electrical Resistivity |
Unit |
%/ºC |
%/ºC |
ΔL/L per ºCx10-6 |
kcal/mhrºC |
cal/gºC |
ºC |
Mpa |
g/cm3 |
Hv |
μΩ • cm |
NdFeB |
-0.09~-0.12 |
-0.45~-0.7 |
//7.5⊥-0.1 |
7.5 |
0.11 |
310~370 |
285 |
7.5 |
620 |
180 |
|