Ulvac, Inc.

Takeo Katou

Hiroshi Nagata

Kyuzo Nakamura

Yoshinori Shingaki

Atsushi Nakatsuka

Ichirou Mukae

Masami Itou

Ryou Yoshiizumi

A permanent magnet is provided which has formed a Dy, Tb film on a surface of an iron-boron-rare earth sintered magnet of a predetermined shape, with diffusion thereof into grain boundary phases, having a higher coercive force. The method of manufacturing a permanent magnet includes a film-forming step of evaporating metal evaporating material containing at least one of Dy and Tb and adhering evaporated metal atoms to a surface of the iron-boron-rare earth sintered magnet, and a diffusing step of performing heat treatment to diffuse metal atoms adhered to the surface into grain boundary phases of the sintered magnet. The metal evaporating material contains at least one of Nd and Pr.

Permanent magnet and method of manufacturing same

There is provided a vacuum evaporating apparatus which is suitable for performing a process in which a metal vapor atmosphere is formed in a processing chamber, the metal atoms in this metal vapor atmosphere are caused to be adhered to the surface of an object to be processed, and the metal atoms adhered to the surface of the object to be processed are diffused into grain boundary phases thereof. The apparatus comprises: a processing furnace (); at least one processing box () disposed inside the processing furnace; and a heating means () provided inside the processing furnace so as to enclose the processing box. An evacuating means is provided which, after housing the processing box inside the processing furnace in a state in which the object to be processed (S) and the metal evaporating material (V) are disposed in the processing box, reduces the processing furnace and the processing box to a predetermined pressure and keep them at that pressure. The heating means is operated in the reduced pressure to evaporate the metal evaporating material while increasing the object to be processed to a predetermined temperature. The evaporated metal atoms are supplied to the surface of the object to be processed.

Vacuum vapor processing apparatus

There is provided a method of manufacturing a permanent magnet which has an extremely high coercive force and high magnetic properties is manufactured at high productivity. There are executed: a first step of causing at least one of Dy and Tb to adhere to at least part of a surface of iron-boron-rare-earth based sintered magnet; and a second step of diffusing, through heat-treatment at a predetermined temperature, at least one of Dy and Tb adhered to the surface of the sintered magnet into grain boundary phase of the sintered magnet. As the sintered magnet, there is used one which is manufactured by: mixing each powder of principal phase alloy (constituted primarily by RTB phase, where R is at least one rare earth element primarily including Nd and where T is a transition metal primarily including Fe), and a liquid phase alloy (having a higher content of R than RTB phase and primarily constituted by R-rich phase) in a predetermined mixing ratio; press-forming in magnetic field a mixed powder thus obtained; and sintering a press-formed body in vacuum or inert gas atmosphere.

By causing at least one of Dy and Tb to be adhered to the surface of an iron-boron-rare earth based sintered magnet of a predetermined shape, and is then to be diffused into grain boundary phase, a permanent magnet can be manufactured at high workability and low cost. An iron-boron-rare earth based sintered magnet is disposed in a processing chamber and is heated to a predetermined temperature. Also, an evaporating material made up of a fluoride containing at least one of Dy and Tb disposed in the same or another processing chamber is evaporated, and the evaporated evaporating material is caused to be adhered to the surface of the sintered magnet. The Dy and/or Tb metal atoms of the adhered evaporating material are diffused into the grain particle phase of the sintered magnet before a thin film made of the evaporated material is formed on the surface of the sintered magnet.

By eliminating the necessity of a prior step for cleaning a sintered magnet before adhering Dy and/or Tb to the surface of the sintered magnet S, the productivity of a permanent magnet having diffused Dy and/or Tb into grain boundary phase is improved. Iron-boron-rare earth based sintered magnet (S) disposed in a processing chamber () is heated to a predetermined temperature. An evaporating material (V) which is made of a hydride containing at least one of Dy and Tb is disposed in the same or in another processing chamber and is evaporated to cause the evaporated evaporating material to the surface of the sintered magnet. Metal atoms of Dy and/or Tb are diffused into grain boundary phase of the sintered magnet.

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Kanagawa, Japan

Takeo Katou