| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a means which can sufficiently control an eddy-current loss and prevent the lowering of a magnet characteristic caused by an insulating material in a permanent magnet in which permanent magnet powder is closely densed where a covering layer formed of the insulating material is formed on the surface. <P>SOLUTION: In the permanent magnet, the permanent magnet powder is closely densed where the covering layer formed of the insulating material is formed on the surface. In the permanent magnet, a relation H≥23,000×d<SP>-1</SP>is satisfied, where covering resistance is H (= t×ρ<SB>r</SB>÷ρ<SB>m</SB>) defined as a value obtained by dividing the product of the thickness t(m) of the covering layer formed of the insulating material and the volume resistance ρ<SB>r</SB>(Ωm) of the permanent magnet powder with a volume resistance coefficient ρ<SB>m</SB>(Ωm) of the permanent magnet powder, and a grain size of the permanent magnet powder is d(mm). <P>COPYRIGHT: (C)2005,JPO&NCIPI |
