Shin-etsu Chemical Co., Ltd.

Masakatsu Honshima

Koji Miyata

Takehisa Minowa

Hajime Nakamura

Koichi Hirota

Naoki Watanabe

Kazuyoshi Watanabe

Hideaki Kikuchi

Yoshio Yamanaka

A sintered Nd base magnet segment has a coercive force high at the periphery and lower toward the inside. A method for preparing the magnet includes the steps of: (a) providing a sintered Nd base magnet block having surfaces and a magnetization direction, (b) coating the surfaces of the magnet block excluding the surface perpendicular to the magnetization direction with a Dy or Tb oxide powder, a Dy or Tb fluoride powder, or a Dy or Tb-containing alloy powder, (c) treating the coated block at a high temperature for causing Dy or Tb to diffuse into the block, and (d) cutting the block in a plane perpendicular to the magnetization direction into a magnet segment having a coercive force distribution on the cut section that the coercive force is high at the periphery and lower toward the inside and a constant coercive force distribution in the magnetization direction.

Nd based sintered magnet

A method for preparing the magnet includes the steps of: (a) providing a sintered Nd base magnet block having surfaces and a magnetization direction, (b) coating the surfaces of the magnet block excluding the surface perpendicular to the magnetization direction with a Dy or Tb oxide powder, a Dy or Tb fluoride powder, or a Dy or Tb-containing alloy powder, (c) treating the coated block at a high temperature for causing Dy or Tb to diffuse into the block, and (d) cutting the block in a plane perpendicular to the magnetization direction into a magnet segment having a coercive force distribution on the cut section that the coercive force is high at the periphery and lower toward the inside and a constant coercive force distribution in the magnetization direction.

Method of manufacturing an Nd based sintered magnet

An axial gap rotating machine rigidly fixing permanent magnets without reducing magnetic flux and having a high output has: a housing; a rotating shaft rotatably supported in the housing; two rotors having disks rotatably integral with the rotating shaft, and permanent magnets arranged concentrically in spaced relation to each other on at least one side of surfaces of the rotating disks in spaced relation to each other on at least one side of surfaces of the rotating disks in spaced relation to each other; and a stator arranged between the rotors, spaced from the rotors and fixed to the housing, the stator having a plurality of coils disposed concentrically around the rotating shaft spaced from each other; wherein magnetic flux generated from the permanent magnets of the rotors intermittently penetrates the interior of each of the coils as the shaft rotates, wherein the rotating disk has a concave portion in the surface facing the stator in which the permanent magnets are disposed so as to protrude.

Axial gap type rotating machine

Permanent magnets are disclosed having a very high coercive force and a very great maximum energy product, and consisting essentially of a rare earth-cobalt based alloy. The alloy is expressed by the formula Sm.sub.1.sub.-u Ce.sub.u (Co.sub.1.sub.-v.sub.-w.sub.-x Cu.sub.v Fe.sub.w Mn.sub.x).sub.z where 0.ltoreq.u.ltoreq.0.20, 0.08.ltoreq.v.ltoreq.0.20, 0.ltoreq.w.ltoreq.0.08, 0.01.ltoreq.x.ltoreq.0.15 and 6.0.ltoreq.z.ltoreq.7.8, preferably 7.2.ltoreq.z.ltoreq.7.8. By using these alloys, the magnetic properties of the resultant permanent magnets are superiorly affected, and the magnet-preparing process is rendered much simplified. This is also because the conventional heat aging step may be eliminated, particularly when the z value is within the preferred range.

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Echizen, Japan

Masakatsu Honshima