Corrosion resistance and coatings of rare earth permanent magnets

Corrosion Resistance of Rare Earth Permanent Magnets

In the Rare Earth Permanent Magnets family, the 1st generation 1:5 type SmCo magnets and 2nd generation 2:17 type SmCo magnets have high corrosion resistance due to the high cobalt content. Just like ferrite/ceramic magnets and AlNiCo magnets, SmCo magnets usually do not need any treatment for applications. The 3rd generation NdFeB magnets, however, are not the same. Although they have superior magnetic properties, they are more vulnerable to corrosion in humid environments, resulting in the deterioration of magnetic properties… Read More

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N42 Magnet and N42SH Neodymium Magnets Demagnetization Curves

Sintered NdFeB Magnet Grades

Generally, the sintered NdFeB magnet grades are strings containing three parts, i.e. “N” + “number” + “letter”. The part “N” is the initial letter of neodymium, meaning it is a sintered neodymium iron boron magnet. So it is constant for all the neodymium magnet grades. The part “number” represents value of maximum energy product (BH)max (in CGS unit). The value varies from 28 to 52. The part “letter” reflects level of intrinsic coercivity Hcj. The levels include “M” (Hcj ≥… Read More

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crystal structures of rare earth permanent magnets smco magnets ndfeb magnets

What are Rare Earth Permanent Magnets (REPMs)?

Rare earth permanent magnets (REPMs) are permanent magnets which are based on some rare earth elements (Sm, Nd, Pr, Dy, Ce, etc.) to form critical magnetic structures. In regard to crystal structures, REPMs include a. 1:5 type SmCo magnets (hexagonal CaCu5 type structure) also called 1st generation REPMs, b. 2:17 type SmCo magnets (rhombohedral Th2Zn17 type structure) also called 2nd generation REPMs and c. Nd2Fe14B magnets (tetragonal crystal structure) also called 3rd generation REPMs. Compared with other types of permanent… Read More

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permanent magnet types

What is a Permanent Magnet?

A permanent magnet is a material that is able to provide magnetic flux when magnetized with an applied magnetic field. The ability is characterized by two key parameters: remanence and coercivity. Generally, a permanent magnet’s intrinsic coercivity (Hcj) is higher than 300kOe (in CGS unit) or 24kA/m (in SI unit). With higher coervivity, a permanent magnet has higher ability to resist demagnetization, including field demagnetization from the electric or magnetic circuit and thermal demagnetization from the working temperature in various… Read More

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