| 摘要 |
PURPOSE:To improve both magnetic characteristic and thermal resistance, by selecting magnetic powder from a group comprising specific ferrite powder, cobalt series rare earth magnet powder and alloy powder, and by using polyphenylene sulfide(PPS) as a binder. CONSTITUTION:In a composite magnet compositions having magnetic powder and polyphenylene sulfide(PPS), said magnetic powder is selected from a group comprising ferrite powder having a general formula; MO.6Fe2O3 in which M represents bivalent metal ion consisting of Ca<2+>, Ba<2+>, Sr<2+> and Pb<2+>, cobalt series rare earth magnet powder having a general formula; RCO5, R2CO17 in which R represents rare earth elements consisting of yttrium, and alloy powder having a general formula; R2T14B in which T represents transition metals. For the PPS used as binder in the composite magnet being produced, when the melt viscosity thereof is excessively high during injection molding in magnetic field, the formability (fluidity in molding) is insufficient and the preferred orientation thereof is lowered, while when the melt viscosity is excessively low, the mechanical strength is reduced to be hardly fit for practicability. Therefore, the melt viscosity is preferably in the range of 1000-2000poises (at a shear rate of 1200/sec, and at 310 deg.C), and is especially preferably in the range of 1200-1700 poises. |
