Comportamento corrosivo dos magnetos NdFeB em meio de sulfato com adicao de tungstato e benzoato

Abstract

The NdFeB alloys shows a high magnetic strength being largely used in industries . However, the presence of the rare earth Nd in the magnets increases the corrosion process, which in tum deteriorates the magnetic proprieties of this alloy. This paper airns to investigate the inhibition action of tungstate and benzoate anions on the corrosion of NdFeB magnet in sulphate media, with and without previous phosphating. The open circuit potential of the bare alloy in tungstate solution shifts toward more positive values under electrode rotation due the enhanced transport of dissolved oxygen, favoring the film repair. The obtained results point out that the alloy resistance after phosphating increases. Under this conditions, the addition of 0.10 mol L tungstate increase the resistance by a factor of 50 in comparison with the bare alloy. At longer immersion time the film remains stable