Avaliacao da resistencia a corrosao de ima de Nd-Fe-B por meio de ensaio gravimetrico

Abstract

Nd-Fe-B permanent magnets are highly susceptible to corrosion in aqueous media. Their excellent magnetic properties, however, make them widely used in applications like electronic motors. The study of their corrosion behavior is of great interest in order to promote its control and to widen the application of these magnets in atmospheres of moderate aggressiveness. The aim of this work was to evaluate the corrosion resistance of a commercial Nd-Fe-B magnet by means of gravimetric analysis. Magnetized and non-magnetized specimens were immersed in NaC1 3.5% (w/w) for increasing periods and after each test period (5, 15, 20, 30, 40 and 60 days) the samples were taken off the solution and weighed. Neutron activation analysis (NAA) of the corrosion products was used as a complementary technique to determine the iron and neodymium contents released from each sample. Weight loss results indicated that the magnets in the magnetized state present lower corrosion resistance than the non-magnetized ones.

Nd-Fe-B permanent magnets are highly susceptible to corrosion in aqueous media. Their excellent magnetic properties, however, make them widely used in applications like electronic motors. The study of their corrosion behavior is of great interest in order to promote its control and to widen the application of these magnets in atmospheres of moderate aggressiveness. The aim of this work was to evaluate the corrosion resistance of a commercial Nd-Fe-B magnet by means of gravimetric analysis. Magnetized and non-magnetized specimens were immersed in NaC1 3.5% (w/w) for increasing periods and after each test period (5, 15, 20, 30, 40 and 60 days) the samples were taken off the solution and weighed. Neutron activation analysis (NAA) of the corrosion products was used as a complementary technique to determine the iron and neodymium contents released from each sample. Weight loss results indicated that the magnets in the magnetized state present lower corrosion resistance than the non-magnetized ones.