Abstract: A magnetic field generator comprises a pair of plate yokes connected by a column yoke. The pair of plate yokes has a pair of opposed surfaces each provided with a permanent magnet including a plurality of neodymium magnets. In a method in which the neodymium magnets are demagnetized and adhesive is ground, the magnetic field generator is heated to 200° C.˜350° C. After the neodymium magnets are demagnetized, the adhesive is removed and the neodymium magnets are removed and collected from the magnetic field generator. In a method in which the adhesive is carbonized, the magnetic field generator is heated to 350° C.˜1000° C. After carbonizing the adhesive, the neodymium magnets are removed and collected. Surfaces of the collected neodymium magnets are polished and the neodymium magnets are reused. Further, the collected neodymium magnets are re-aged and reused.

Abstract: Rare earth alloy powder having an oxygen content of 50 to 4000 wt. ppm and a nitrogen content of 150 to 1500 wt. ppm is compacted by dry pressing to produce a compact. The compact is impregnated with an oil agent and then sintered. The sintering process includes a first step of retaining the compact at a temperature of 700° C. to less than 1000° C. for a period of time of 10 to 420 minutes and a second step of permitting proceeding of sintering at a temperature of 1000° C. to 1200° C. The average crystal grain size of the rare earth magnet after the sintering is controlled to be 3 ?m to 9 ?m.

Abstract: A method of making an alloy powder for an R—Fe—B-type rare earth magnet includes the steps of preparing a material alloy that is to be used for forming the R—Fe—B-type rare earth magnet and that has a chilled structure that constitutes about 2 volume percent to about 20 volume percent of the material alloy, coarsely pulverizing the material alloy for the R—Fe—B-type rare earth magnet by utilizing a hydrogen occlusion phenomenon to obtain a coarsely pulverized powder, finely pulverizing the coarsely pulverized powder and removing at least some of fine powder particles having particle sizes of about 1.0 ?m or less from the finely pulverized powder, thereby reducing the volume fraction of the fine powder particles with the particle sizes of about 1.0 ?m or less, and covering the surface of remaining ones of the powder particles with a lubricant after the step of removing has been performed.

Abstract: A thin-film magnetic head wafer includes a first principal surface and a second principal surface which are substantially parallel to each other. An electrical/magnetic transducer is provided on the first principal surface. Identification information is recorded on the first principal surface of the wafer.

Abstract: A process for treating surfaces of rare earth metal-based permanent magnets, comprising removing an oxide layer formed on a surface of each of the permanent magnets using a blasting apparatus. The apparatus comprises a tubular barrel formed of a mesh net for accommodation of work pieces and supported circumferentially outside a center axis of a support member rotatable about the center axis, and an injection nozzle disposed to inject a blast material against the work pieces from the outside of the tubular barrel, wherein at least one of the tubular barrel and the support member is detachably mounted. The process further comprises removing the tubular barrel or the support member from the blasting apparatus and attaching the tubular barrel or the support member to a vapor deposited film forming apparatus, where a metal film is formed on the surface of each of the permanent magnets by a vapor deposition process.

Abstract: A magnetic field generator comprises a pair of plate yokes connected by a column yoke. The pair of plate yokes has a pair of opposed surfaces each provided with a permanent magnet including a plurality of neodymium magnets. In a method in which the neodymium magnets are demagnetized and adhesive is ground, the magnetic field generator is heated to 200° C.˜350° C. After the neodymium magnets are demagnetized, the adhesive is removed and the neodymium magnets are removed and collected from the magnetic field generator. In a method in which the adhesive is carbonized, the magnetic field generator is heated. to 350° C.˜1000° C. After carbonizing the adhesive, the neodymium magnets are removed and collected. Surfaces of the collected neodymium magnets are polished and the neodymium magnets are reused. Further, the collected neodymium magnets are re-aged and reused.

Abstract: A magnetic field generator (10) capable of generating a more intense magnetic field, and an MRI apparatus (200) using it are provided. Permanent magnets (12a), (12b), (14a), (14b), (16a), (16b), (18a), (18b), (20a), (20b), (22) and (24) are disposed annularly for formation of a magnetic field generation space (30). Ferromagnetic materials (26a) and (26b) are provided near the magnetic field generation space (30), at places passed by a magnetic flux. Each of the permanent magnets (12a), (14a), (16a), (18a) and (20a) surrounding the ferromagnetic material (26a) is magnetized so as to make an S pole on the side of the ferromagnetic material (26a). Each of the permanent magnets (12b), (14b), (16b), (18b) and (20b) surrounding the ferromagnetic material (26b) is magnetized so as to make an N pole on the side of the ferromagnetic material (26b). An MRI apparatus (200) is obtained by using the magnetic field generator (10).

Abstract: A plate yoke has an upper surface formed with a projection and a guiding rail. A new magnet block is transported by sliding on the upper surface of the plate yoke, and is bonded side by side with the projection or a magnet block which is already fixed. During the above operation, a magnetic member is held above the plate yoke. Preferably, the new magnet block is transported toward a corner portion, with side surfaces of the magnet block held parallel to a side surface of the projection and a side surface of the guiding rail respectively. When the magnet unit and the column yoke is connected, the column yoke or the magnet unit is lowered so that a guiding rod attached to an end face of the column yoke is inserted into a hole formed in the magnetic unit. Further, the column yoke is guided by a guiding member disposed between a permanent magnet on the plate yoke and a position where the column yoke is to be connected on the plate yoke.

Abstract: A method of making a sintered body for a rare earth magnet includes the steps of (a) preparing a first coarse powder by coarsely pulverizing a rare earth alloy sintered body by a hydrogen pulverization process, (b) preparing a first fine powder by finely pulverizing the first coarse powder, (c) preparing a second fine powder by pulverizing an alloy block of a rare earth alloy material, and (d) sintering a mixed powder including the first and second fine powders. The first and second fine powders each includes a main phase represented by (LR1-xHRx)2T14A, where T is Fe and/or at least one non-Fe transition metal element; A is boron and/or carbon; LR is at least one light rare earth element; HR is at least one heavy rare earth element; and 0?x<1.

Abstract: A dry surface treating apparatus of the present invention comprises, within a treating chamber, a surface-treating material supply section and a tubular barrel having a porous peripheral surface for accommodating a work piece, to treat a surface of the work piece while rotating the tubular barrel horizontally arranged about a horizontal rotational axis, wherein the tubular barrel has a slide stop for stopping a slide of the accommodated work piece along an inner peripheral surface of the tubular barrel due to rotation of the tubular barrel. According to the dry surface treating apparatus of the invention, because the work piece is inverted of surfaces within the tubular barrel, the time the work piece at each surface faces the surface-treating material supply section is made equivalent. Consequently, it is possible to provide even deposited-film formation or surface treatment to the opposite surfaces of a work piece, particularly, a rare earth metal-based permanent magnet in a plate or bow form.

Abstract: A rare earth metal-based permanent magnet has a film layer formed substantially of only a fine metal powder on a metal forming the surface of the magnet. The rare earth metal-based permanent magnet having the film layer on its surface is produced in the following manner: A rare earth metal-based permanent magnet and a fine metal powder forming material are placed into a treating vessel, where both of them are vibrated and/or agitated, whereby a film layer made of a fine metal powder produced from the fine metal powder producing material is formed on a metal forming the surface of the magnet. Thus, the formation of a corrosion-resistant film such as plated film can be achieved at a high thickness accuracy by forming an electrically conductive layer uniformly and firmly on the entire surface of the magnet without use of a third component such as a resin and a coupling agent.

Abstract: A recycling method for a magnetic field generator, which includes a plate yoke, and a permanent magnet provided on the plate yoke, the magnetic field generator further including a plurality of neodymium magnets bonded together by an adhesive. The magnetic field generator is heated to 200° C.˜1000° C., then at least one of the plurality of neodymium magnets is removed; and a surface of the removed neodymium magnet is polished for reusing the neodymium magnet.

Abstract: The present invention provides a rare-earth sintered magnet exhibiting desirable magnetic properties in which the amount of Nd and/or Pr forming a non-magnetic phase in a grain boundary phase is reduced. Specifically, the present invention provides a rare-earth sintered magnet having a composition of (R1x+R2y)T100-x-y-zQz where R1 is at least one element selected from the group consisting of all rare-earth elements excluding La (lanthanum), Y (yttrium) and Sc (scandium); R2 is at least one element selected from the group consisting of La, Y and Sc; T is at least one element selected from the group consisting of all transition elements; Q is at least one element selected from the group consisting of B and C, and including, as a main phase, a crystal grain of an Nd2Fe14B crystalline structure, wherein: molar fractions x, y and z satisfy 8?x?18 at %, 0.1?y?3.

Abstract: A perpendicular pressing/compacting method for a rare-earth alloy powder is provided to produce a sintered magnet with excellent magnetic properties. A method for pressing a rare-earth alloy powder by using a die is provided. The die is made of a non-magnetic material and has a die hole to define a cavity and a pair of yoke members provided on both sides of the cavity. The method includes the steps of: providing the rare-earth alloy powder; filling the cavity of the die with the rare-earth alloy powder; and compressing the rare-earth alloy powder, loaded in the cavity, between a pair of opposed press surfaces. A pulse magnetic field substantially perpendicular to a compressing direction is not applied until the apparent density of the rare-earth alloy powder in the cavity reaches a predetermined value, at least equal to 47% of the true density thereof, while the compressing step is being carried out.

Abstract: A method for manufacturing a sintered magnet includes the steps of producing a green compact of powder for the sintered magnet, machining the green compact with a wire-saw, and sintering the green compact.

Abstract: An apparatus for grinding a magnetic member comprises a cutting blade having a cutting edge including heat resistant resin and abrasive grain. A magnetic member including a rare-earth alloy is ground by the cutting blade while grinding fluid primarily made of water is supplied to a grinding region. A magnet separator having a surface magnetic flux density not smaller than 0.25 T magnetically separates sludge from used grinding fluid. Further, the grinding fluid is introduced into a tank, where the sludge contained in the grinding fluid is allowed to coagulate and sediment. The grinding fluid separated from the sludge is used in circulation. The same separation process can be used for separation of sludge containing a rare-earth alloy from waste fluid.

Abstract: A powder compacting method includes the steps of: providing a powder material; loading the powder material into a cavity; uniaxially pressing the powder material, which has been loaded into the cavity, between two opposed press surfaces, thereby obtaining a compact, wherein at least one of the two press surfaces is deformed elastically under a compacting pressure when contacting with the powder material in the cavity; and unloading the compact from the cavity. According to this powder compacting method, even when the powder material has a non-uniform fill density distribution, a compact with a uniform density distribution can be obtained at a high productivity.

Abstract: A magnetic field generator (10) which generates a high uniformity magnetic field at a plurality of locations is provided. The magnetic field generator (10) includes a pair of plate yokes (12a),(12b) which are faced to each other with a gap (G) in between. A pair of mutually opposed magnetic poles (14a),(14b), and another pair of mutually opposed magnetic poles (16a),(16b) are provided between the plate yokes (12a),(12b). The magnetic poles (14a),(14b) respectively include permanent magnet groups (18a),(18b) which are disposed on mutually opposed surfaces of the plate yokes (12a),(12b). Pole pieces (20a),(20b) are fixed to mutually opposed surfaces respectively of the permanent magnet groups (18a),(18b). The magnetic poles (16a),(16b) respectively include permanent magnet groups (22a),(22b) which are disposed on mutually opposed surfaces of the plate yokes (12a),(12b). Pole pieces (24a),(24b) are fixed to mutually opposed surfaces respectively of the permanent magnet groups (22a),(22b).

Abstract: A method of cutting a rare-earth alloy with a wire saw, obtained by fixing abrasive grains on a core wire with a resin layer, includes the step of moving the wire saw while a portion of the rare-earth alloy being machined with the wire saw is immersed in a coolant, which is mainly composed of water and has a surface tension of about 25 mN/m to about 60 mN/m at about 25° C., thereby cutting the rare-earth alloy. In the wire saw, an average distance between two of the abrasive grains, which are adjacent to each other in a length direction, is about 150% to less than about 400% of the average grain size of the abrasive grains, an average height of portions of the abrasive grains, protruding from the surface of the resin layer, is about 70% or less of the average grain size of the abrasive grains, and a thickness deviation percentage of the resin layer with respect to the core wire is about 40%.

Abstract: In a process for handling green compacts made from a rare earth metal-based magnetic alloy powder by a press machine to slide, on a sintering support plate, the green compacts, the support plate used has a surface roughness degree Ra in a range of 0.6 to 47 ?m. At a first step, the green compacts are disposed in a first position near a final transport position, and at a second step, the said green compacts disposed in the first position are slid on the sintering support plate and disposed in the final transport position. Thus, by using the support plate having a surface roughness degree in a particular range, the green compacts made from the rare earth metal-based magnetic alloy powder can be sintered without occurrence of the deposition of the green compacts to the support plate, the chipping of the green compacts and the like. In addition, the efficiency of operation of the press machine can be increased.