Understanding the Mechanism of Degradation of Nd-Fe-B Permanent Magnets in Different Environments

摘要

The corrosion behaviour of Nd-Fe-B permanent magnetic alloy has been studied in detail both in marine and industrial environments with a view to understand the degradation mechanism of the magnet in different environments. The results revealed that the alloy could not form a protective oxide scale on its surface and corrosion rate of the alloy enhances by more than 9 times in industrial environment when compared to marine environment. The studies demonstrate that degradation of magnet takes place due to galvanic coupling among the phases present in the magnetic alloy and mode of degradation is intergranular in nature. Based on the results, a degradation mechanism has been proposed leading to the failure of magnets during service in both the studied environments. Finally, the importance of surface engineering has been mentioned and stressed the necessity of innovation of suitable surface coatings for their maximum exploitation both in industrial as well as marine environments.