Temperature stability of SmCo (2:17) magnets modified by Ni–Cr two-layer coating
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The oxidation resistance behavior of SmCo (2:17)-type high-temperature magnets modified with Ni–Cr two-layer coating was studied. The study depicts the mass gain kinetics and magnetic properties of uncoated and Ni–Cr-modified magnets oxidized at high temperature (500 °C) in air for 200 h. The oxidation test results illustrate that the mass gain of uncoated magnet is 6.95 mg·cm−2 which is more than that (0.08 mg·cm−2) of coated magnet after 200 h. For the magnetic properties concerned, there is a great loss for uncoated magnet, while for coated magnet, magnetic properties do not change much. The study of uncoated magnet through X-ray diffraction (XRD) and electron probe microanalysis (EPMA) shows that the invasion of oxygen at high temperature leads to the loss of magnetic properties by changing the microstructure of magnet.
KeywordsSmCo (2:17) magnets Surface modification High temperature stability Ni–Cr coating
This work was financially supported by the National Science Foundation of China (No. 51471016) and the Natural Science Foundation of Beijing (No. 2151002).
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