| 摘要 |
PROBLEM TO BE SOLVED: To easily evaluate a degree of penetration of NdCu into a magnet using no rare metal, without magnetizing the magnet in a non-destructive manner.SOLUTION: A magnet 20 is held by a pair of electrodes 12. Control measurement means 18 controls a frequency-variable AC power supply 14 to supply an AC current to the magnet 20 while varying frequency. A depth of the magnet 20 supplied with the AC current is changed by means of a skin effect. An electric resistance value of the magnet 20 is measured by the control measurement means 18. On the basis of the consideration that electric resistance of the magnet 20 is reduced in a portion where NdCu penetrates, a degree of penetration of NdCu into the magnet 20 is evaluated on the basis of a frequency of the AC current supplied to the magnet 20 (a depth of the magnet 20 supplied with the current) and the measured electric resistance value of the magnet 20. The magnet 20 can be easily evaluated without magnetization in a non-destructive manner. |
