| 简介 |
A metal powder with anisotropic magnetic properties is mixed with a liquid thermosetting plastic and added to a molding tool(1). A magnetic orientation of magnetic properties is then performed and the mixed compound pressed(6, 7) and cured to form a solid magnet. - Magnetic orientation, compression and molding of the compound occurs at not more than 100 deg. C. A lubricant may be included in the compound. Compound is added to the compression tool under influence from a magnetic field with a magnetic gradient in the filling direction. Field strength at the filling opening(2) is not less than 10mT/m. The main component of the magnetic field(5) can be either transverse to or parallel to the compaction direction(3). Compound may also be premagnetized before adding to the tool(1), in which case the magnetic field strength is greater than the coercive field strength, typically not less than 400kA/m, of the metal powder. Packing density(PD) or volumetric content(%) of magnetic powder in a magnet at a compaction pressure(p) in MPa is at least PD asterisk where PD asterisk =(p divided by 100)+68. Magnetic powder preferably makes up not less than 70vol% of a magnet. Bending strength of a magnet is not less than 20N/sq mm. After pressing demagnetization can be achieved by applying a magnetic field opposing the orientation field(8). Polymer content of the compound is 2-20vol%. Curing of the magnet may occur outside the molding tool. Independent claims are included for : a) a compound for producing a magnet comprising a liquid thermosetting material and magnetic powder with anisotropic magnetic properties; b) a plastic bound anisotropic magnet with a metal content of not less than 50wt% of a permanently magnetic metal powder based on a rare earth(SE) alloy with a hard magnetic phase of type SE2TM14B, SETM5 or SE2TM17, where TM is a transition metal and a liquid thermosetting polymer comprising 0.2-4.5wt% of the compound. |
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