Corrosion of Nd-Fe-B permanent magnets

Purpose: purpose of the paper is to 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. Design/methodology/approach: Corrosion tests were made in two corrosive environments in water and in 5% NaCl solution. Findings: 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. Practical implications: Magnets covered by protective polymer, lacquer or metal coating are less susceptible to corrosion so employment of these coatings can lower the losses caused by the corrosion of magnets. Corrosion protection of Nd-Fe-B magnets needs further investigations. Originality/value: 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 obtained results can be use in practice to decrease the corrosion wear of these materials.