from the conferences organized by TANGER Ltd.
Research in the field of magnetic materials based on Nd-Fe-B is focused on the improvement of certain magnetic characteristics by alloying of suitable elements (Co, Dy, Pr, Cu), extending the thermal stability of these permanent magnets, improving their corrosion resistance and the creation of nano-structure modifications. Magnets based on Nd-Fe-B are susceptible to corrosion, especially in humid atmospheres. The corrosion resistance of these magnets is a function of the structure, temperature, degree of environment humidity and Nd-rich phase reactivity. The paper is focused on determining and comparing the corrosion resistance of magnetic material NdPr-FeM-B (produced by powder metallurgy, M = Cu,Co,Al) in several environments. For comparative purposes, unalloyed carbon steel (C ≤ 0.1 wt.%) was tested under the same conditions. On the basis of electrochemical polarization measurements there were determined polarization curve, corrosion characteristics and parameters (corrosion potential, polarization resistance, pitting potentials, etc.) of mentioned selected materials in aqueous solutions (Na2SO4, NaH2PO4, NaCl). Salt spray test was also performed with these materials. The heterogeneous structure of magnetic material and uneven and/or localized corrosion was observed using microscopy. In the sodium chloride solution, a higher corrosion resistance reached steel in comparison with the magnet, in sodium sulfate solutions the results were not clear (depending on the pH, surface condition). The magnetic material exhibited a much higher resistance in the solution of NaH2PO4 in comparison with the corrosion resistance in other test solutions.
Keywords: magnetic material, Nd-Fe-B, corrosion resistance, polarization test© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.