ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Nd-Fe-B magnets present outstanding magnetic properties. However, due to their lowcorrosion resistance, their applications are limited to non-corrosive environments. Nowadays,significant efforts are underway to increase the corrosion resistance of these materials, throughthe use of coatings. Herein are presented the results of a study on the corrosion resistance ofNd-Fe-B magnets coated with polypyrrole (PPY). The electrochemical behavior of coated anduncoated magnets has been studied by Electrochemical Impedance spectroscopy (EIS) insynthetic saliva. The results were compared to previous investigations, which were carried outunder similar conditions, in Na2SO4 and NaCl solutions. In sulphate solution, the corrosionresistance of the PPY-coated magnet was 3 times larger (1600 [removed info].cm2) than that of uncoatedmagnet (500 [removed info].cm2). In NaCl solution, however, the corrosion resistance of coated anduncoated magnets were very similar (250 [removed info].cm2). In synthetic saliva, both the uncoated andcoated magnets presented good corrosion performance (1940 [removed info].cm2). Such behavior can beattributed to the phosphate ions in saliva, which play a role as corrosion inhibitor, producingphosphating, at least partially, of the magnet surface. The PPY-coated magnets presented astrong diffusional control from moderate to low frequencies, caused by the polypyrrole film.The thicker PPY film increased the corrosion resistance of the magnet in synthetic saliva
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/14/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.530-531.111.pdf
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