Wpływ warunków środowiskowych na starzenie magnesów trwałych Nd-Fe-B

The paper presents results of corrosion wear of bonded and sintered hard magnetic materials Nd-Fe-B and magnets covered by protective polymer, lacquer and metal coatings. Corrosion tests were made in the water and in 5% NaCl solution environment. It was found that the bonded magnets with the polymer matrix demonstrate better corrosion resistance than the sintered magnets. Employment of the protective coatings on the Nd-Fe-B bonded magnets surfaces may feature the effective protection of the substrate material from the corrosive action of the aggressive agent. Analysis of the surface topography of the deposited protective coatings makes it possible to determine coating defects resulting from the action of the aggressive agent. The best protection from the corrosive environment is provided by the polymer coatings. Lower corrosion protection by protective coating was found in the case of sintered magnets. The corrosion damage process of magnets covered with the protective coatings starts in the coating failure location and is connected with the further damage proceeding both into the material and on its surface.