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magnetic materials

corrosion studies

An important achievement in the field of nanocrystalline powders and sintered magnets based on Nd-Fe-B was the improvement of the intrinsic corrosion resistance by introducing small amounts of additives such as ZrO2. ZrO2 reacts with free Nd in the grain boundary phase and Nd2O3 and ZrB2 phases are formed. The sensitivity of the grain boundaries is diminished and consequently the corrosion resistance is improved.
To further improve the chemical stability of the sensitive powders we developed and patented a coating procedure for the powders by using long-chain fatty acids or silanes.


The mechanism of the chemical coating

With this method a chemical bond between the powder's surface and a surface-active agent is formed (Figure) and a thin organic layer on the surface allows for the free handling of the powder under atmospheric conditions. This is of special importance for industrial use. (Patent)

 

comments & suggestions to:  sanja fidler