Intermetallics Co., Ltd.

Sumitomo Special Metals Co., Ltd.

Daido Steel Co., Ltd.

Other

Ugimag Sa

Tomoegawa Paper Co., Inc.

Mitsubishi Corporation

Sumitomo Special Metal Co. Ltd.

Aimants Ugimag Sa

Ndfeb Corporation

Masato Sagawa

Aimants Ugimag

Setsuo Fujimura

Yutaka Matsuura

Hiroshi Nagata

Hitoshi Yamamoto

Tetsuhiko Mizoguchi

Osamu Itatani

Norio Togawa

Fernand Vial

Hiroo Shirai

Toshihiro Watanabe

Naoki Fujimoto

Norio Yoshikawa

Philippe Tenaud

Tochihiro Watanabe

Hiroshi Watanabe

Satoshi Hirosawa

Shinobu Takagi

Akira Fujiwara

Hayato Hashino

Shinichi Hayashi

Takao Suzuki

Yasuhiro Une

Armand Gabriel

Pierre Turillon

Alain Barzasi

Mizuho Kasahara

Terumasa Miyoshi

A method for producing an NdFeB sintered includes forming a layer containing Dy and/or Tb on the surface of an NdFeB sintered magnet base material and then performing a grain boundary diffusion process for diffusing Dy and/or Tb from the aforementioned layer through the crystal grain boundaries of the magnet base material into the magnet base material by heating the magnet base material to a temperature equal to or lower than the sintering temperature thereof. In this method: a) the content of a rare earth in a metallic state in the magnet base material is equal to or higher than 12.7 at %; b) the aforementioned layer is a powder layer formed by depositing a powder; and c) the powder layer contains Dy and/or Tb in a metallic state by an amount equal to or higher than 50 mass %.

NdFeB sintered magnet and method for producing the same

There is provided a production method and a production device for producing each of the rare earth sintered magnet sintered bodies without carrying a mold in a sintering furnace. The method includes feeding an alloy powder into a mold having side walls divided into two or more sections; filling the alloy powder into the mold to prepare a filled molded-body; orienting the alloy powder in the filled molded-body by applying a magnetic field to the filled molded-body to prepare an oriented filled-molded-body; detaching the side walls of the mold from the oriented filled-molded-body and retrieving the oriented filled-molded-body from the mold; and sintering the retrieved oriented filled-molded-body. The filling step and the orienting step are performed at different locations. A pulsed magnetic field can be applied in the orienting step and inside of the mold can be partitioned into a plurality of cavities by partitions.

Production method of rare earth sintered magnet and production device used in the production method

The present invention aims to provide a NdFeB system sintered magnet capable of improving the magnetization characteristic. The NdFeB system sintered magnet is a NdFeB system sintered magnet with the c axis oriented in one direction, characterized in that: the median of the grain size of the crystal grains at a section perpendicular to the c axis is 4.5 &#x3bc;m or less, and the area ratio of the crystal grains having grain sizes of 1.8 &#x3bc;m or smaller on the aforementioned section is 5% or lower. The median of the grain size is decreased (to 4.5 &#x3bc;m or less), whereby improve the coercive force is improved. Simultaneously, the area ratio of the crystal grains having grain sizes of 1.8 &#x3bc;m or smaller is decreased (to 5% or lower) to reduce the number of crystal grains having no magnetic wall formed, whereby the magnetization characteristic is improved.

NdFeB system sintered magnet

A method for producing an RFeB system magnet with high coercivity by preventing a coating material from peeling off the surface of a base material during a grain boundary diffusion treatment is provided. A method for producing an RFeB system magnet which is a sintered magnet or a hot-deformed magnet containing, as the main rare-earth element, a light rare-earth element Rwhich is at least one of the two elements of Nd and Pr, the method including: applying, to a surface of a base material M of the RFeB system magnet, a coating material prepared by mixing a silicone grease and an R-containing powder containing a heavy rare-earth element Rcomposed of at least one element selected from the group of Dy, Tb and Ho; and heating the base material together with the coating material. Improved coating and base materials adhesion facilitates transfer of Rinto base material grain boundaries.

RFeB system magnet production method, RFeB system magnet, and coating material for grain boundary diffusion treatment

A NdFeB system sintered magnet produced by the grain boundary diffusion method that has a high coercive force and squareness ratio with only a small decrease in the maximum energy product. The NdFeB system sintered magnet has a base material produced by orienting powder of a NdFeB system alloy and sintering the powder, with Dy and/or Tb (the 'Dy and/or Tb' is hereinafter called R) attached to and diffused from a surface of the base material through the grain boundary inside the base material by a grain boundary diffusion treatment, wherein the difference C-Cbetween the Rcontent C(wt %) in the grain boundary reaching the surface to which Ris attached and the Rcontent C(wt %) in the grain boundary at a depth of 3 mm from the aforementioned attachment surface is equal to or smaller than 20 wt %.

A NdFeB system sintered magnet produced by the grain boundary diffusion method and has a high coercive force and squareness ratio with only a small decrease in the maximum energy product. A NdFeB system sintered magnet having a base material produced by orienting powder of a NdFeB system alloy and sintering the powder, with Dy and/or Tb (the 'Dy and/or Tb' is hereinafter called R) attached to and diffused from a surface of the base material through the grain boundary inside the base material by a grain boundary diffusion treatment, wherein the difference C&#x2212;Cbetween the Rcontent C(wt %) in the grain boundary and the Rcontent C(wt %) in main-phase grains which are grains constituting the base material at the same depth within a range from the surface to which Ris attached to a depth of 3 mm is equal to or larger than 3 wt %.

An applicator for grain boundary diffusion process that uniformly applies an RH powder without excess or deficiency onto a predetermined surface of a sintered compact with a given thickness and in a given pattern, the applicator being automated and performed on many sintered compacts during the production of a NdFeB system sintered magnet. The applicator includes a work loader and a print head, located above the work loader. The work loader includes: a laterally movable base; a lift being vertically movable with respect to the base; a frame that is attachable to and detachable from the lift; a tray that is attachable to and detachable from the frame; a supporter provided on the upper surface of the tray; and a vertically movable magnetic clamp. The print head includes: a screen having a passage section; and a movable squeegee and a backward scraper that maintains contact with the upper screen surface.

Applicator for grain boundary diffusion process

A method for producing a NdFeB system sintered magnet. The method includes: a hydrogen pulverization process, in which coarse powder of a NdFeB system alloy is prepared by coarsely pulverizing a lump of NdFeB system alloy by making this lump occlude hydrogen; a fine pulverization process, in which fine powder is prepared by performing fine pulverization for further pulverizing the coarse powder; a filling process, in which the fine powder is put into a filling container; an orienting process, in which the fine powder in the filling container is oriented; and a sintering process, in which the fine powder after the orienting process is sintered as held in the filling container. The processes from hydrogen pulverization through orienting are performed with neither dehydrogenation heating nor evacuation each for desorbing hydrogen occluded in the hydrogen pulverization process. The processes from hydrogen pulverization through sintering are performed in an oxygen-free atmosphere.

Method for producing NdFeB system sintered magnet

A mold which is inexpensive and easy to process and does not embrittle. Also provided is a process by which a sintered NdFeB magnet can be produced using the mold without suffering bending or deformation. At least part (e.g., a bottom plate) of the mold is made of a carbon material. Carbon materials have lower friction with a sinter during sintering than metals. The mold hence enables a sintered NdFeB magnet to be produced without suffering the bending or deformation caused by friction due to sintering shrinkage. Carbon materials are inexpensive and easy to process. The mold does not embrittle even when repeatedly used. Such effects can be significantly produced when a carbon material is used as the bottom plate, on which the load of the sinter is imposed during sintering.

Method for making NdFeB sintered magnet and mold for making the same

Disclosed is a sintered NdFeB magnet having high coercivity (H) a high maximum energy product ((BH)) and a high squareness ratio (SQ) even when the sintered magnet has a thickness of 5 mm or more. The sintered NdFeB magnet is produced by diffusing Dy and/or Tb in grain boundaries in a base material of the sintered NdFeB magnet by a grain boundary diffusion process. The sintered NdFeB magnet is characterized in that the amount of rare earth in a metallic state in the base material is between 12.7 and 16.0% in atomic ratio, a rare earth-rich phase continues from the surface of the base material to a depth of 2.5 mm from the surface at the grain boundaries of the base material, and the grain boundaries in which Rhas been diffused by the grain boundary diffusion process reach a depth of 2.5 mm from the surface.

Sintered NdFeB magnet and method for manufacturing the same

A powder-filling system capable of filling a container with powder at an approximately uniform filling density has: a hopper having an opening removably and hermetically closably attached to the container, the hopper communicating with the container at the opening for supplying powder to a container; a powder supplier for supplying powder to the hopper; a gas supplier for repeatedly supplying compressed gas in a pulsed form to the hopper, with the hopper hermetically closably attached to the container; and a sieve member provided at the opening and having a smaller openings in a region near a side wall of the hopper than in its central region. The smaller openings in the region near the side wall of the hopper where the powder more easily falls from the hopper into the container impedes the fall of the powder in that region and improves the overall uniformity in the filling density.

Powder-filling system

A NdFeB system sintered magnet produced by the grain boundary diffusion method and has a high coercive force and squareness ratio with only a small decrease in the maximum energy product. A NdFeB system sintered magnet having a base material produced by orienting powder of a NdFeB system alloy and sintering the powder, with Dy and/or Tb (the 'Dy and/or Tb' is hereinafter called R) attached to and diffused from a surface of the base material through the grain boundary inside the base material by a grain boundary diffusion treatment, wherein the difference C-Cbetween the Rcontent C(wt %) in the grain boundary and the Rcontent C(wt %) in main-phase grains which are grains constituting the base material at the same depth within a range from the surface to which Ris attached to a depth of 3 mm is equal to or larger than 3 wt %.

A NdFeB system sintered magnet according to the present invention is a NdFeB system sintered magnet having a base material produced by orienting powder of a NdFeB system alloy and sintering the powder, with Dy and/or Tb (the 'Dy and/or Tb' is hereinafter called R) attached to and diffused from a surface of the base material through the grain boundary inside the base material by a grain boundary diffusion treatment, wherein the number of grain-boundary triple points at which the difference C&#x2212;Cbetween the Rcontent C(wt %) at the grain-boundary triple point and the Rcontent C(wt %) at a two-grain boundary portion leading to that grain-boundary triple point is equal to or smaller than 4 wt % is equal to or larger than 60% of the total number of grain-boundary triple points.

Provided is a NdFeB sintered magnet which can be used in the grain boundary diffusion method as a base material in which Rcan be easily diffused through the rare-earth rich phase and which itself has a high coercive force, a high maximum energy product and a high squareness ratio, as well as a method for producing such a magnet. A NdFeB system sintered has an average grain size of the main-phase grains magnet is equal to or smaller than 4.5 &#x3bc;m, the carbon content of the entire NdFeB system sintered magnet is equal to or lower than 1000 ppm, and the percentage of the total volume of a carbon rich phase in a rare-earth rich phase at a grain-boundary triple point in the NdFeB system sintered magnet to the total volume of the rare-earth rich phase is equal to or lower than 50%.

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Kyoto, Japan

Masato Sagawa