Electrodepositing apparatus and preparation of rare earth permanent magnet

Patent metadata

Field	Value
Publication number	US-10017871-B2
Application number	US-201514625277-A
Country	US
Kind code	B2
Filing date	Feb 18, 2015
Priority date	Feb 19, 2014
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

An electrodepositing apparatus is provided comprising an inner tank ( 1 ) filled with an electrodepositing solution, an outer tank ( 3 ), a feedback means ( 4 ), a rectifying member ( 5 ) disposed in the inner tank ( 1 ), a means ( 8 ) for holding an article (p), a counter electrode ( 6 ), and a power supply ( 9 ). The electrodepositing solution is circulated in such a way that it overflows the inner tank and is fed back from the outer tank to the inner tank by the feedback means, the flow of the solution is rectified by the rectifying member to keep flat the solution surface in the inner tank, a selected portion of the article is immersed in the solution, and the coating agent is electrodeposited on the selected portion of the article.

First claim

The invention claimed is:

1. A method for preparing a rare earth permanent magnet, comprising the steps of:
coating a sintered magnet body having a R 1 —Fe—B base composition, wherein R 1 is at least one element selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, with a powder comprising at least one member selected from the group consisting of an oxide, fluoride, oxyfluoride, hydride, and rare earth alloy of R 2 , wherein R 2 is at least one element selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and
heat treating the coated magnet body for causing R 2 to be absorbed in the magnet body,
wherein the coating step includes the steps of:
providing an electrodepositing apparatus comprising
an inner tank filled with an electrodepositing solution and adapted to effect electrodeposition on an article immersed in the solution, wherein a peripheral wall of the inner tank is provided, at an upper edge of the peripheral wall, with a plurality of equally spaced apart V-shaped notches across which the electrodepositing solution overflows,
an outer tank enclosing the inner tank so that the outer tank receives an overflow of the electrodepositing solution from the inner tank,
a feedback system comprising a flow-out pipe extending from the outer tank and a return pipe extending back to the inner tank near the bottom of the inner tank,
a rectifying plate disposed at a vertical intermediate position in the inner tank and horizontally extended so as to divide the inner tank into upper and lower compartments, the rectifying plate having a plurality of first apertures distributed so that the rectifying plate rectifies flow of the electrodepositing solution and suppresses waves in the surface of the electrodepositing solution overflowing from the upper rim of the inner tank,
an article holder configured to hold the article so that the article is partially immersed in the electrodepositing solution in the inner tank,
a counter electrode, with a plurality of second apertures, disposed in the inner tank and opposed to the article which is to be held by the article holder and immersed in the electrodepositing solution, and
a power supply for applying a predetermined voltage between the article and the counter electrode,
circulating the electrodepositing solution in such a way that it overflows the inner tank into the outer tank and is fed back from the outer tank to the inner tank near its bottom by the feedback system,
immersing a selected portion of the magnet body in the electrodepositing solution in the inner tank, the electrodepositing solution comprising a solvent and the powder dispersed in the solvent, and
electrodepositing the powder on the surface of the magnet body to form a powder coating on the selected portion of the magnet body by actuating the power supply to apply the predetermined voltage between the article and the counter electrode.

2. The method of claim 1 , wherein the inner tank includes a bottom wall, the return pipe having a plurality of orifices in its tubular wall, the return pipe being connected to the feedback system and extended through the inner tank along the bottom wall, and the feedback system feeds the electrodepositing solution into the return pipe to inject the electrodepositing solution into the inner tank through the orifices.

3. The method of claim 2 , wherein the orifices are arranged in the return pipe such that their diameter gradually or stepwise decreases from the proximal end to the distal end of the return pipe.

4. The method of claim 1 , wherein the counter electrode is a metal plate and disposed on the rectifying plate.

5. The method of claim 4 wherein the counter electrode is a metal disk, the disk being generally frusto-conical shaped at a central portion or over its entirety.

6. The method of claim 1 , further comprising at least one of a level meter, thermometer, concentration meter, and flow meter.

Assignees

• Shinetsu Chemical Co

Inventors

• Kuribayashi Yukihiro
• Nagasaki Yoshifumi

Classifications

• H01F41/0293 Primary

  diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets · CPC title

• H01F1/086

  sintered · CPC title

• H01F1/0577

  sintered · CPC title

• C25D17/02

  Tanks; Installations therefor · CPC title

• C25D17/12

  Shape or form (C25D17/14 takes precedence) · CPC title