Abstract: A sintered magnet production mold which can improve the uniformity in the filling density of the alloy powder. The main body has a main cavity formed inwards from a main-body surface and a side cavity provided on the outside of the opening of the upper cavity on the main-body surface at each of the two ends of the opening in the axial direction of the aforementioned partial cylinder, the side cavity formed inwards from the main-body surface and shaped like a partial cylinder having an axis parallel to the axis of the partial cylinder of the lower cavity. The cover has a base surface corresponding to the main-body surface and a convex rib bulging from the base surface, the convex rib having a shape corresponding to the two side cavities and a virtual cavity shaped like a partial cylinder connecting the two side cavities.

Abstract: A method for producing an RFeB system sintered magnet with the main phase grains having a grain size of 1 ?m or less with a considerably equal grain size, including: preparing a shaped body oriented by a magnetic field and sintering the shaped body, wherein the shaped body is prepared using an alloy powder of an RFeB material having a particle size distribution with an average value of 1 ?m or less in terms of a circle-equivalent diameter determined from a microscope image, the alloy powder obtained by pulverizing coarse particles having fine crystal grain, each coarse particle having grains of the RFeB material formed inside, the crystal grains having a crystal grain size distribution with an average value of 1 ?m or less in terms of the circle-equivalent diameter determined from a microscope image, and 90% by area or more of the crystal grains being separated from each other.

Abstract: 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.

Abstract: A method having a pulverizing process in which a lump of alloy of a material for a sintered magnet is pulverized by a method including a hydrogen pulverization method, filling process wherein a cavity is filled with alloy powder obtained by pulverizing process, an orienting process wherein alloy powder is magnetically oriented by applying magnetic field to alloy powder, and sintering process wherein alloy powder is sintered by heating it according to predetermined temperature history. In the sintering process, alloy powder is heated in inert-gas atmosphere at higher pressure than atmospheric pressure until temperature reaches predetermined pressurization maintenance temperature which is higher than hydrogen desorption temperature and equal to or lower than sintering temperature. By performing the heating treatment in a pressurized inert gas, hydrogen-gas molecules remaining in the alloy powder are prevented from suddenly desorbing from alloy powder, so that the cracking of the sintered magnets hardly occurs.

Abstract: Provided is a NdFeB sintered magnet which can be used in the grain boundary diffusion method as a base material in which RH can 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 ?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%.

Abstract: A sintered magnet producing apparatus is provided having a device for fixing a filling container and a lid for the container in the process of orienting alloy powder in the filling container by means of a magnetic field. The sintered magnet producing apparatus includes a filling system for supplying an alloy powder into a filling container and then compacting the alloy powder, a sintering device for sintering the alloy powder, an orienting device having a coil for generating a magnetic field for orienting the alloy powder in the filling and sintering container before the filling process and after the compacting process, and a fixing device for covering the filling container with a lid, and simultaneously, fixing the filling container only during the orienting process. The filling container is prevented from moving due to the magnetic field applied in the orienting process and, simultaneously, the scattering of the alloy powder is prevented.

Abstract: A NdFeB sintered magnet production system including: a first weight unit for measuring the mold weight when the alloy powder is not yet filled; a guide attachment unit to extend the mold cavity with a guide to form a supply cavity with a predetermined volume; a powder supply unit for supplying the alloy powder into the supply cavity so that the alloy powder volume is equal to the supply cavity capacity; a filling unit for pressing the alloy powder contained in the supply cavity into the mold cavity to densify the alloy powder to the filling density; a second weight unit for measuring the mold weight after being filled with the alloy powder; and a controlling unit for computing the alloy powder weight filled into the mold cavity based on the difference between the measurement value from each of the first weight unit and the second weight unit.

Abstract: The objective of the present invention is to provide a method for making a NdFeB sintered magnet, capable of enhancing the effect of increasing the coercive force and preventing the instability of the effects, and in addition, being inexpensive. The method for making a NdFeB sintered magnet according to the present invention has processes of coating a NdFeB sintered magnet with a powder containing Dy and/or Tb, then heating the NdFeB sintered magnet, and thereby diffusing Rh in the powder into the NdFeB sintered magnet through a grain boundary, and is characterized in that the powder contains 0.5 through 50 weight percent of Al in a metallic state; and the amount of oxygen contained in the NdFeB sintered magnet is equal to or less than 0.4 weight percent.

Abstract: 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 RH) 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 Ct-Cw between the RH content Ct (wt %) at the grain-boundary triple point and the RH content Cw (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.

Abstract: 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 RH) 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 Cgx-Cx between the RH content Cgx (wt %) in the grain boundary and the RH content Cx (wt %) in main-phase grains which are grains constituting the base material at the same depth within a range from the surface to which RH is attached to a depth of 3 mm is equal to or larger than 3 wt %.

Abstract: The present invention is aimed at providing a sintered magnet production system that can prevent the influences of a leaking magnetic field in an orienting process. A sintered magnet production system according to the present invention has a filling means 11 for filling an alloy powder into a filling/sintering container, a sintering means 13 for sintering the alloy powder, and an orienting means 12 with an air-core coil for producing a magnetic field for orienting the alloy powder in the filling/sintering container after the filling process and before the sintering process, the axis of the air-core coil being displaced from a straight line connecting the filling means 11 and the sintering means 13. The magnetic field leaking from the orienting means 12 is strongest on the extended line of the axis of the air-core coil and relatively weak in the direction perpendicular to the extended line.

Abstract: A method for manufacturing a sintered rare-earth magnet having a magnetic anisotropy, in which a very active powder having a small grain size can be safely used in a low-oxidized state. A fine powder as a material of the sintered rare-earth magnet having a magnetic anisotropy is loaded into a mold until its density reaches a predetermined level. Then, in a magnetic orientation section, the fine powder is oriented by a pulsed magnetic field. Subsequently, the fine powder is not compressed but immediately sintered in a sintering furnace. A multi-cavity mold for manufacturing a sintered rare-earth magnet having an industrially important shape, such as a plate magnet or an arched plate magnet, may be used.

Abstract: The present invention is aimed at providing a method for producing an NdFeB sintered magnet having a higher coercivity and higher squareness of the magnetization curve than ever before. A method for producing an NdFeB sintered magnet according to the present invention includes the steps of 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, and this method is characterized in that a) the content of a rare earth in a metallic state in the magnet base material is equal to or higher than 12.

Abstract: A method for manufacturing a sintered rare-earth magnet having a magnetic anisotropy, in which a very active powder having a small grain size can be safely used in a low-oxidized state. A fine powder as a material of the sintered rare-earth magnet having a magnetic anisotropy is loaded into a mold until its density reaches a predetermined level. Then, in a magnetic orientation section, the fine powder is oriented by a pulsed magnetic field. Subsequently, the fine powder is not compressed but immediately sintered in a sintering furnace. A multi-cavity mold for manufacturing a sintered rare-earth magnet having an industrially important shape, such as a plate magnet or an arched plate magnet, may be used.

Abstract: A method for producing a sintered NdFeB magnet having high coercivity and capable of being brought into applications without lowering its residual magnetic flux density or maximum energy product and without reprocessing. The method includes applying a substance containing dysprosium (Dy) and/or terbium (Tb) to the surface of the sintered NdFeB magnet forming a base body and then heating the magnet to diffuse Dy and/or Tb through the grain boundary and thereby increase the coercivity of the magnet. This method is characterized in that: (1) the substance containing Dy or Tb to be applied to the surface of the sintered NdFeB magnet is substantially a metal powder; (2) the metal powder is composed of a rare-earth element R and an iron-group transition element T, or composed of R, T and another element X, the element X capable of forming an alloy or intermetallic compound with R and/or T; and (3) the oxygen content of the sintered NdFeB magnet forming the base body is 5000 ppm or lower.

Abstract: 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 %.

Abstract: The present invention provides a method for producing a sintered NdFeB magnet having high coercivity and capable of being brought into applications without lowering its residual magnetic flux density or maximum energy product and without reprocessing. The method for producing a sintered NdFeB magnet according to the present invention includes applying a substance containing dysprosium (Dy) and/or terbium (Tb) to the surface of the sintered NdFeB magnet forming a base body and then heating the magnet to diffuse Dy and/or Tb through the grain boundary and thereby increase the coercivity of the magnet.

Abstract: The present invention is aimed at providing a method for producing an NdFeB sintered magnet having a higher coercivity and higher squareness of the magnetization curve than ever before. A method for producing an NdFeB sintered magnet according to the present invention includes the steps of 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, and this method is characterized in that a) the content of a rare earth in a metallic state in the magnet base material is equal to or higher than 12.

Abstract: A NdFeB sintered magnet production system including: a first weight unit for measuring the mold weight when the alloy powder is not yet filled; a guide attachment unit to extend the mold cavity with a guide to form a supply cavity with a predetermined volume; a powder supply unit for supplying the alloy powder into the supply cavity so that the alloy powder volume is equal to the supply cavity capacity; a filling unit for pressing the alloy powder contained in the supply cavity into the mold cavity to densify the alloy powder to the filling density; a second weight unit for measuring the mold weight after being filled with the alloy powder; and a controlling unit for computing the alloy powder weight filled into the mold cavity based on the difference between the measurement value from each of the first weight unit and the second weight unit.

Abstract: 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.