# US 8,771,422 B2 · Coating method and apparatus, a permanent magnet, and manufacturing method thereof

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- Number: US 8,771,422 B2
- Document ID: US8771422B2
- Status: Granted
- Kind: B2
- Application number: 13/163,881
- Filed: 2011-06-20
- Published: 2011-12-01
- Granted: 2014-07-08
- Earliest claimed: 2005-03-18
- Assignees: Ulvac, Inc.
- Applicants: Hiroshi Nagata; Yoshinori Shingaki
- Inventors: Hiroshi Nagata; Yoshinori Shingaki
- Web page: https://patentgrep.com/patent/US8771422B2

## CPC

- C23C 14/16: on metallic substrates or on substrates of boron or silicon
- C23C 14/243: {Crucibles for source material (C23C14/28, C23C14/30 take precedence)}
- C23C 14/541: {Heating or cooling of the substrates}
- H01F 10/126: {containing rare earth metals (H01F10/133 takes precedence)}
- H01F 41/0293: {diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets}
- H01F 41/20: by evaporation
- H01F 1/0571: {in the form of particles, e.g. rapid quenched powders or ribbon flakes}
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

The object of the present invention is to improve the productivity of a permanent magnet and to manufacture it at a low cost by effectively coating Dy and Tb on a surface of the magnet of Fe—B-rare earth elements having a predetermined configuration. The permanent magnet of the present invention is manufactured by a coating step for coating Dy on the surface of the magnet of Fe—B-rare earth elements having a predetermined configuration and a diffusing step for diffusing Dy coated on the surface of the magnet into crystal grain boundary phases of the magnet with being heat treated at a predetermined temperature. In this case, the coating step comprises a first step for heating a process chamber used for carrying out the coating step and generating metallic vapor atmosphere within the process chamber by vaporizing vaporizable metallic material previously arranged within the process chamber, and a second step for introducing into the process chamber the magnet held at a temperature lower than that within the process chamber and then selectively depositing the vaporizable metallic material on a surface of the magnet by an effect of temperature difference between the temperature within the process chamber and that of the magnet by the magnet reaches a predetermined temperature.

## Claims

### Claim 1

A coating apparatus comprising:
a process chamber having an annular acceptor configured to place thereon a vaporizable metallic material;
a heater configured to heat substantially uniformly an inside of the process chamber to a predetermined temperature;
a preparatory chamber in communication with the process chamber;
an evacuating pump configured to hold both the process and the preparatory chambers at a predetermined degree of vacuum;
a valve moveable between an opened position in which the process and the preparatory chambers are in communication with each other and a closed position in which the process chamber is sealed from the preparatory chamber;
a support member configured to move an article to be coated between the process chamber and the preparatory chamber and seal the process chamber from the preparatory chamber when the article to be coated is moved into the process chamber;
the process chamber being housed inside a vacuum chamber, the vacuum chamber having a second evacuating pump;
the process chamber being defined by a uniform-heating member having on one side thereof an opening; and
the heater being disposed between the uniform-heating member and an insulating material, the insulating material enclosing a circumference of the uniform-heating member except for the opening so that the heater can heat the uniform-heating member, to thereby selectively deposit the vaporizable metallic material on a surface of the article to be coated by an effect of a temperature difference between the predetermined temperature within the process chamber and a temperature of the article to be coated,
wherein the acceptor is mounted to an inner surface of the uniform-heating member such that the vaporizable metallic material is arranged around the article to be coated when the article to be coated is moved into the process chamber by the support member.

### Claim 2 (depends on 1)

A coating apparatus of claim 1 further comprising a gas input for introducing inert gas into the preparatory chamber, and the inert gas is introduced into the preparatory chamber via the gas input so as to hold the pressure within the process chamber at a negative pressure relative to that of the preparatory chamber.

### Claim 3 (depends on 1)

A coating apparatus of claim 1 wherein the preparatory chamber is equipped with a gas input for introducing He gas into the preparatory chamber, and the He gas is introduced into the preparatory chamber via the gas input so as to hold the pressure within the process chamber at substantially same as that within the preparatory chamber.

### Claim 4 (depends on 3)

A coating apparatus of claim 3 wherein the process chamber is arranged below the preparatory chamber.

### Claim 5 (depends on 1)

A coating apparatus of claim 1 wherein the preparatory chamber is equipped with a plasma generator for cleaning the surface of article to be coated by using plasma.

### Claim 6 (depends on 1)

A coating apparatus of claim 1 wherein the preparatory chamber is equipped with another heater for cleaning the surface of the article to be coated by heat treatment by introducing an inert gas into the vacuum atmosphere of the preparatory chamber via a gas input connected thereto.

### Claim 7 (depends on 1)

A coating apparatus of claim 1 wherein the vaporizable metallic material is alloy including either one of Dy or Tb or including at least one of Dy and Tb, and the article to be coated is a sintered magnet of Fe—B-rare earth elements having a predetermined configuration.

### Claim 8 (depends on 1)

A coating method using the coating apparatus of claim 1, the method comprising:
a first step for heating the process chamber and generating a metallic vapor atmosphere within the process chamber by vaporizing the vaporizable metallic material previously arranged within the process chamber, and
a second step for introducing into the process chamber articles to be coated held at a temperature lower than the predetermined temperature within the process chamber and then selectively depositing the vaporizable metallic material on the surface of an article to be coated by the effect of the temperature difference between the predetermined temperature within the process chamber and the temperature of the article to be coated.

### Claim 9 (depends on 8)

A coating method of claim 8 wherein the metallic vapor atmosphere is in a saturated condition within the process chamber.