| 摘要 |
PROBLEM TO BE SOLVED: To reduce high frequency loss by controlling the magnetic permeability at the surface of a sheet to equal to or above specified times of the magnetic permeability at the middle part of the sheet. SOLUTION: The magnetic permeability at the surface of the sheet is controlled to >=2 times of the magnetic permeability at the center part of the sheet. Preferably the magnetic permeability at the surface of the soft magnetic sheet composed of a silicon steel plate having Si concentration gradient in the thickness direction is >=2 times of the magnetic permeability at the center part of the sheet and <=3.5% Si is contained in the whole thickness of the steel plate on an average. Further, the thickness of high magnetic permeability part from the surface is desirably >=5% of the plate thickness. As a result, for example, the loss of a 6.5 wt.% Si-containing homogeneous material (the quantity of Si is 6.5 wt.% through whole thickness) of a Fe-Si alloy sheet, which has most excellent soft magnetic property, enables to be reduced by max. 30% in this new magnetic sheet. The soft magnetic sheet low in high frequency iron loss, which is suitable for a core of a transformer, a reactor, a motor or the like, is obtained without deteriorating machinability and decreasing the sheet thickness. |
