Abstract
Corrosion behaviour of three commercial sintered Nd–Fe–B
magnets exposed to environments containing water as
vapour, pressurised vapour, and liquid was investigated
in order to understand their overall corrosion
performance under a range of conditions. Two types of
heat humidity exposure tests, namely the 85/85 and
pressure cooker test, and the immersion test combined
with electrochemical measurements were used as corrosion
tests. It was observed that varying the temperature,
pressure, and the prevailing state of water in the
exposure tests, different corrosion mechanisms were
detected on the surface of Nd–Fe–B magnets. The surface
finish of the magnet had an effect on the initiation of
corrosion in mild heat-humidity exposure. Immersion in
liquid water resulted in a corrosion topography where the
Nd-rich grain-boundary phase did not corrode selectively
as in the other accelerated corrosion tests but was
retained intact while the matrix phase underwent
corrosion. These results and the dominant corrosion
mechanisms of sintered Nd–Fe–B magnets in different
environments are presented and discussed in this paper.
| Original language | English |
|---|---|
| Pages (from-to) | 349-359 |
| Journal | Journal of Alloys and Compounds |
| Volume | 626 |
| DOIs | |
| Publication status | Published - 2015 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- corrosion
- electrochemical impedance spectroscopy
- permanent magnets
- rare earth alloys
- rare earth compounds
- scanning electron microscopy