Coating integrity and magnetic performance of reused magnets

As part of a recycling strategy, magnets are heated up to the Curie temperature of approximately 350 deg. Celsius. To which degree this causes any change to the magnetic performance, as well as any degradation of the coating quality, and thereby expected lifetime of the magnet, is investigated. Preliminary findings suggest that the magnetic performance is not affected by the Curie Temperature, but it is, however, important to not exceed this. Of the 4 different coatings (NiCuNi, NiCu+Epoxy, Zn, Epoxy), NiCu+Epoxy seems to be the best candidate for the proposed recycling strategy based on the results from coating pull-off tests, salt-spray tests, and light-optical microscopy of the interface between coating and magnets.

Caption: The preparation of test samples in which the four different coatings are heat-treated 1 or 5 times in a nitrogen saturated furnace.

Contact: Nenad Mijatovic, nm@elektro.dtu.dk, +45 4525 3525