How much thermal demagnetization index can be improved by direct copper plating on NdFeB?

Rare earth Nd-Fe-B permanent magnet materials are widely used in the fields of electronic information, motor, household appliances, automobile manufacturing, general machinery, petrochemical industry, wind power generation and cutting-edge technology due to their good magnetic properties, small size and high cost performance. However, Nd-Fe-B material is easy to be corroded, so strict anti-corrosion treatment must be carried out before use. As a mature metal surface treatment method, electroplating is widely used in the field of Nd-Fe-B magnet anti-corrosion.

 Neodymium magnet

The majority of NdFeB products are small parts, so barrel plating is widely used. The most common barrel plating methods of NdFeB are barrel galvanizing and barrel nickel plating. Generally, the combination of nickel + copper + nickel coating is used in barrel nickel plating, that is, the combination of bottom nickel + thickened copper + surface nickel. However, for magnets with high magnetic properties, “Ni + Cu + Ni” is difficult to meet the requirements of thermal demagnetization.


The thermal demagnetization index of NdFeB is the same as the magnetic flux value, magnetic energy product, coercivity and material demagnetization curve. The demagnetization rate is used to reflect the demagnetization index. The smaller the demagnetization rate is, the more qualified the thermal demagnetization index is.


The production practice shows that the thermal demagnetization of NdFeB is closely related to the base nickel. The thermal demagnetization performance of NdFeB can be greatly improved if the base copper is directly plated instead of nickel.


So, how much can NdFeB direct copper plating improve the thermal demagnetization index?


The maximum demagnetization rate of the finished product is not more than 4%, and the average demagnetization rate is less than 2.5% (the demagnetization rate of “Ni + Cu + Ni” is generally not less than 5% ~ 8%), with good stability and consistency

Post time: Jan-12-2021
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