Rare earth metal protection mechanisms

In previous sections, rare earth metal (REM)-based inhibitors have been acknowledged as good candidates to substitute the chromate-based inhibitors. Nevertheless, despite the numerous studies performed to understand the mechanisms of protection they offer [39,58-73,145,146], the exact mechanism of deposition is still under debate... 

Besides the measures described in the main part of this paper, significant improvement of the corrosion resistance of a material can be obtained by use of inhibitors. In this case, good results seem to be achieved with rare earths employed in low amounts as alloying metals or as protective dense oxide coatings. The use of coatings often means the research into the best compromise between mechanical properties and corrosion resistance of the material. 

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