Patent ID: 6770242
Filing Date: 2004-08-03
Classification: B22F,H01F,H02K

Abstract:
A method for producing permanent rare earth magnets used in voice control actuator motors comprising the steps of:a. providing prealloyed rare earth magnetic alloys in particulate form, b. attriting a predetermined volume of said prealloyed rare earth particulate materials under a protective non-reactive fluid blanket having substantially higher density than that of water, with the dual purpose of breaking up any aggregates and of mechanically removing any adsorbed volatiles, moisture, atmospheric gases or contaminants from the surface of said prealloyed rare earth particulate materials or from the fresh surfaces generated during attrition, c. separating any contaminants thus removed from the deaggregated particulates, d. removing the protective fluid blanket from the thus decontaminated deaggregated particulates using vacuum distillation, e. desorbing the surface of the said particulates by applying a sufficiently high vacuum, f. allowing a predetermined volume of a suitable surfactant to adsorb onto the surface of the said particulates such that at least 25% and at most 50% of the said particulates' surface is coated with a monolayer of surfactant, g. dispersing said partially surfactant-coated particulates in a predetermined volume of a suitable degradable thermoplastic binder to form a homogeneous thermoplastic compound, h. shaping said thermoplastic compound into green preforms in a magnetic field, i. dewaxing and sintering said green preforms in accordance with prior art practice.