| 摘要 |
PURPOSE:To improve the stength and appearance of a permanent magnet by means wherein more plastic binder is contained in its surface layer than in its inner part. CONSTITUTION:Magnetic dust and plastic binder compose a permanent magnet. The ratio of the plastic binder to the magnetic dust is high in a magnet surface layer 3 and low in a magnet inner part 8. Plastic binder in the surface layer 3 increases elastic strength and protects the magnet from external force caused cracks, nicks, and from falling off of magnetic dust. |
