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MA: Magnetismus

MA 3: Magnetische Materialien

MA 3.5: Vortrag

Montag, 24. März 2003, 11:15–11:30, HSZ/401

Corrosion Behaviour of RE-Fe-B-based Bonded Magnets — •Mihaela Rada, Anke Kirchner, Annett Gebert, Kirrill Khlopkov, Oliver Gutfleisch, and Ludwig Schultz — IFW Dresden, Postfach 27 0016, 01171

RE-Fe-B commercial powders (Magnequench) prepared by rapidly quenching (MQP-12-14, MQP-B) as well as anisotropic NdFeB powder (MQA-T) prepared by HDDR have been used for production of polymer-bonded magnets by compression molding. The magnetic materials were mixed with different amounts of epoxy resin (2wt.% - 4wt.%) and pressed at 600 MPa using a hydraulic laboratory press. Hardening of the material took place in-situ at a temperature of 175 degrees Celsius in vacuum. The demagnetisation curves of the polymer-bonded magnets were measured on a Permeameter. For the evaluation of the corrosion properties weight-loss measurements as well as electrochemical polarization measurements were performed using a rotating disc electrode in a three-electrodes cell. The samples were investigated in two N2 -purged electrolytes: 0,1 M sulfuric acid (pH=1) and 0,1 M sodium sulfate (pH=5). Before and after corrosion testing, the samples surfaces were investigated by means of high-resolution scanning electron microscopy (HRSEM). The results are compared to those obtained for fully dense hot pressed samples. A relation between the magnets composition, the magnetic properties and corrosion resistance is discussed.