Korozní vlastnosti magnetů typu NdRE-Fe-B s ochrannými kovovými povlaky

Abstract

This diploma thesis deals with the corrosion properties of permanent magnets based on NdRE-Fe-B, with protective coatings applied galvanically. The theoretical part of the diploma thesis is focused on the basic acquaintance with neodyme magnets. From the magnetic field, chemical composition, production process, recycling, protective coatings to the corrosion process and its testing. The experimental part of the diploma thesis deals with evaluation of thicknesses and of individual layers (base Ni/Cu/Ni and outer Ag, Au, Cr, Sn). The coating thicknesses were determined perpendicular to the coating, but also at an angle, and then the actual coating thicknesses were determined according to the standard. Furthermore, the structure of the magnet and the surface defects of the protective coatings were evaluated. The corrosion properties of individual coatings were compared using potentiodynamic polarization measurements.