As already discussed in previous sections, the NdFeB magnet has various grades:- each grade has its own magnetic properties (relating to strength of magnetic field output and resistance to demagnetisation, maximum recommended operating temperature and temperature coefficients).
The grades have other physical properties which are similar between the grades
The Effects of Radiation on Neodymium Iron Boron, NdFeB, magnets
The NdFeB magnets may be demagnetised by radiation. The Neodymium Rare Earth magnets do not perform as well as SmCo Rare Earth magnets. E.W. Blackmore, (TRIUMF, 1985) and A.F. Zeller & J.A. Nolen (National Superconducting Cyclotron Laboratory, 09/87) demonstrated SmCo having a better performance, with Sm2Co17 offering 2-40 times better radiation resistance than NdFeB. Some NdFeB grade are demagnetised to half their maximum performance with a proton beam radiation of 4 x 106 rads and are completely demagnetised with a proton beam radiation of 7 x 107 rads. A rule of thumb is to select magnets with higher Hci values, designed to operate at high Pci and, where possible, to have radiation shielding protecting them when being subjected to any levels of radiation. The user of the magnets would need to test for effectiveness of the magnets as the magnet suppliers do not have the equipment to test for suitability of magnet grades for environments with raised levels of radiation.
Structural use of Neodymium Iron Boron, NdFeB, magnets
There is a risk of chipping or breaking the magnets because all magnets are inherently brittle. The Neo magnets are less brittle than SmCo. It is advised to not put magnets in conditions of mechanical stress e.g. in load bearing situations.
There is a risk of chipping or breaking the magnets because all magnets are inherently brittle. The Neo magnets are less brittle than SmCo. It is advised to not put magnets in conditions of mechanical stress e.g. in load bearing situations.
The Effects of Radiation on Neodymium Iron Boron, NdFeB, magnets
The NdFeB magnets may be demagnetised by radiation. The Neodymium Rare Earth magnets do not perform as well as SmCo Rare Earth magnets. E.W. Blackmore, (TRIUMF, 1985) and A.F. Zeller & J.A. Nolen (National Superconducting Cyclotron Laboratory, 09/87) demonstrated SmCo having a better performance, with Sm2Co17 offering 2-40 times better radiation resistance than NdFeB. Some NdFeB grade are demagnetised to half their maximum performance with a proton beam radiation of 4 x 106 rads and are completely demagnetised with a proton beam radiation of 7 x 107 rads. A rule of thumb is to select magnets with higher Hci values, designed to operate at high Pci and, where possible, to have radiation shielding protecting them when being subjected to any levels of radiation. The user of the magnets would need to test for effectiveness of the magnets as the magnet suppliers do not have the equipment to test for suitability of magnet grades for environments with raised levels of radiation.
