| 简介 |
PROBLEM TO BE SOLVED : To provide a rare earth-based permanent magnet having an Mg-containing Al coating on the surface thereof and exhibiting excellent salt water resistance, and to provide a manufacturing method thereof.
SOLUTION : The rare earth-based permanent magnet having an Mg-containing Al coating on the surface thereof is characterized in that the Mg concentration of the coating is higher in the outer surface side than in the side of the interface with the magnetic body in the thickness direction of the coating and the magnet has a layer in which Al and/or Mg are (is) oxidized and/or hydroxylated in the surface of the outer surface side of the coating. The manufacturing method thereof is characterized in that the method includes : evaporation-forming an Mg-containing Al coating on the surface of a rare earth-based permanent magnet in a treatment chamber of an evaporation apparatus; cooling the magnet having such a high temperature as 160°C or more by quenching the magnet with a cooling rate of 10°C/min or more until the temperature of the magnet reaches at least 60°C; and subjecting the surface of the obtained coating of the rare earth-based permanent magnet having an Mg-containing Al coating on the surface thereof to oxidization and/or hydroxylation of Al and/or Mg in the coating.
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