Method for preparing rare earth magnet

Abstract

The method for preparing the rare earth magnet of the present invention is as follows: Use a jig (6) to arrange a plurality of sintered compacts (7) side by side such that the first surface (21) of the plurality of sintered compacts (7) is along a plane parallel to the vertical direction; in a first film-forming treatment chamber (5) provided with a target (4) arranged on the first surface (21) side of the plurality of sintered compacts (7), form a film on the first surface (21) of the plurality of sintered compacts (7) arranged side by side using the jig (6); in a second film-forming treatment chamber (25) arranged side by side with the first film-forming treatment chamber (5) and provided with a target (4) arranged on the second surface (22) side of the plurality of sintered compacts (6), form a film on the second surface (22) of the plurality of sintered compacts (7) arranged side by side using the jig (6); between the first film-forming treatment chamber (5) and the second film-forming treatment chamber (25), move the plurality of sintered compacts (7) arranged side by side using the jig (6) in the horizontal direction. According to the present invention, a method for preparing a rare earth magnet can be provided, which can stably and in large quantities prepare a high-performance rare earth magnet by using the grain boundary diffusion method of a film formed by physical vapor deposition.

Description

Technical Field

[0001] The present invention relates to a method for producing a rare earth magnet. For a production process of a high-performance magnet with a small amount of Tb or Dy used, such as forming a rare earth metal film or a rare earth alloy film on the surface of a rare earth sintered body, performing heat treatment, and causing the sintered body to absorb rare earth elements in the film, the production method can significantly improve its productivity. Background Art

[0002] Rare earth permanent magnets such as Nd-Fe-B sintered magnets are increasingly widely used due to their excellent magnetic properties. As the main applications, rotating machines can be cited. In these applications, rare earth permanent magnets are required to have heat resistance at temperatures of 100 to 200°C. Therefore, the coercivity of Nd-Fe-B sintered magnets at room temperature needs to be sufficiently increased. To increase the coercivity, a method of replacing a part of Nd with Tb or Dy has been adopted. However, these elements have problems in terms of performance such as reducing the saturation magnetic polarization of the magnet and problems in terms of resources such as being rare elements, and these problems have become obstacles to the expansion of the applications of Nd-Fe-B sintered magnets.

[0003] Therefore, the following method has been developed: Tb or Dy is disposed on the surface of the produced sintered body, and by performing heat treatment below the sintering temperature, Tb or Dy diffuses into the magnet, and a very small amount of Tb or Dy is distributed on the grain surface of the magnet. Thus, the coercivity can be significantly increased with almost no reduction in the saturation magnetic polarization. At the beginning of the discovery of this phenomenon, as a method of disposing Dy on the magnet surface, the sputtering method (Non-Patent Document 1) was used. However, due to its low production efficiency, it cannot be considered a mass-production process. Then, a three-dimensional sputtering method (Patent Document 1) that can form a film on the entire surface of the magnet by disposing the sintered body in a rotating cage was developed. However, the size and shape of the sintered body that can be processed are limited, and mass production cannot be achieved. Among them, a method such as making a slurry from rare earth compound powders such as rare earth oxides, rare earth fluorides, and rare earth oxyfluorides and impregnating and coating them on the sintered body was discovered (Patent Document 2). Since its productivity is high, it was first used in the mass production process. In addition, methods such as using Dy vapor (Patent Documents 3 and 4) or a method of adhering rare earth compound powders such as rare earth metals, rare earth alloys, and rare earth hydrides to the magnet surface (Patent Documents 5 and 6) have been developed. This method, called the grain boundary diffusion method, is widely used as a production method for high-performance and high-heat-resistant Nd-Fe-B sintered magnets.

[0004] Among them, regarding the film made by the initially discovered sputtering method, not only can the film thickness be controlled with high precision, but the magnet made by diffusing it has higher performance than other methods. Nevertheless, due to its significantly low productivity, the sputtering method is difficult to apply to mass production.

[0005] In the case of magnets for electric rotating machines, which are the largest application for rare-earth magnets, the magnets are mostly flat and close to a plate shape. From the viewpoint of effectively utilizing the magnet performance, it is appropriate that the pole face is the widest face. In the three-dimensional sputtering apparatus described in Patent Document 1, by rotating a cage in which a flat and close-to-plate-shaped magnet is placed, a film can be formed on all surfaces of the magnet by one treatment, and in this regard, high productivity can be expected. However, for the magnet shape for electric rotating machines, since the sintered body cannot rotate uniformly in the cage, the film is likely to be uneven, eliminating the advantages of using the sputtering method.

[0006] However, in such a shape, by forming and diffusing a film containing rare-earth elements only on two surfaces, which are the widest surfaces, rather than on all surfaces of the sintered body, a large coercivity increasing effect can be obtained. In the case of using a normal sputtering apparatus, in order to improve workability, it is preferable to arrange a target above the sputtering chamber, place a plurality of sintered bodies on a tray having approximately the same area or the same width as the target, and arrange the tray below the target.

[0007] However, in this configuration, a film can be formed only on one of the two wide surfaces of the sintered body. Therefore, after forming a film on one surface of the sintered body, it is necessary to reliably reverse the sintered body on the tray and re-introduce the sintered body into the sputtering chamber to form a film on the remaining one surface. When reversing, an automatic reversing device for reversing each tray occupies a large space. In addition, although reversing by manual operation can save space, the risk of quality problems such as forgetting to reverse increases.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-304038

[0011] Patent Document 2: International Publication No. WO2006 / 043448

[0012] Patent Document 3: International Publication No. WO2008 / 023731

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 2008-263223

[0014] Patent Document 5: International Publication No. WO2008 / 120784

[0015] Patent Document 6: International Publication No. WO2008 / 032426.

[0016] Non-Patent Documents

[0017] Non-Patent Document 1: K. T. Park, K. Hiraga, and M, Sagawa, "Effect of Metal-Coating and Consecutive Heat Treatment on Coercivity of Thin Nd-Fe-B Sintered Magnets", Proceedings of the Sixteenth International Workshop on Rare-Earth Magnets and Their Applications, Sendai, p. 257 (2000). Summary of the Invention

[0018] Problems to be Solved by the Invention

[0019] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a method for producing a rare earth magnet, which is a highly productive method in the so-called grain boundary diffusion method. In this method, a film is formed on the surface of a sintered body composed of an R 1 -Fe-B system (R 1 is one or more elements selected from rare earth elements, and one or two of Pr and Nd are essential) by physical vapor deposition, and R 2 (R 2 is one or more elements selected from rare earth elements, and one or two of Tb and Dy are essential) is absorbed by the sintered body through subsequent heat treatment.

[0020] Means for Solving the Problems

[0021] The inventors of the present invention conducted in-depth research to achieve the above object, and as a result, found that by arranging in parallel a plurality of film-forming chambers in which targets (previously only arranged above) and sintered bodies are arranged vertically or horizontally, it is possible to obtain a highly productive production method in which a film containing R 2 can be formed on two opposite surfaces of the sintered body by a single loading, thus completing the present invention.

[0022] (1) A method for producing a rare earth magnet, which includes the following grain boundary diffusion step: on a plurality of sintered bodies composed of an R 1 -Fe-B system (R 1 is one or more elements selected from rare earth elements, and one or two of Pr and Nd are essential), and each having a first surface and a second surface opposite to the first surface, a film selected from R 2 film, R 2 -M alloy film, and R 2and a multilayer film of R and M (R 2 is one or more elements selected from rare earth elements, wherein one or two elements of Tb and Dy are essential, and M is one or more elements selected from Cu, Al, Co, Fe, Mn, Ni, Sn, and Si) are formed into one or more films, and then R 2 or R 2 and M are absorbed by the sintered body; characterized in that a plurality of the sintered bodies are arranged in parallel using a jig such that a first surface of the plurality of sintered bodies is along a plane parallel to the vertical direction or the horizontal direction, and the grain boundary diffusion process includes: a first film forming process of forming the film on the first surface of the plurality of sintered bodies arranged in parallel using the jig in an inert gas atmosphere in a first film forming chamber provided with a target containing the R 2 ; a second film forming process of forming the film on the second surface of the plurality of sintered bodies arranged in parallel using the jig in an inert gas atmosphere in a second film forming chamber provided with a target containing the R 2 and arranged in parallel with the first film forming chamber; and a moving process of moving the plurality of sintered bodies arranged in parallel using the jig between the first film forming chamber and the second film forming chamber in the horizontal direction or the vertical direction.

[0023] (2) The method for preparing a rare earth magnet according to (1), characterized in that the first film forming chamber and the second film forming chamber are each formed by connecting a plurality of film forming chambers in series, and the plurality of sintered bodies are continuously formed into films in an inert gas atmosphere without being exposed to the atmosphere.

[0024] (3) A method for preparing a rare earth magnet, which includes the following grain boundary diffusion process: on a plurality of sintered bodies composed of an R 1 -Fe-B system (R 1 is one or more elements selected from rare earth elements, wherein one or two elements of Pr and Nd are essential) and each having a first surface and a second surface opposite to the first surface, by physical vapor deposition, one or more films selected from an R 2 film, an R 2 -M alloy film, and a multilayer film of R 2 and M (R 2 is one or more elements selected from rare earth elements, wherein one or two elements of Tb and Dy are essential, and M is one or more elements selected from Cu, Al, Co, Fe, Mn, Ni, Sn, and Si) are formed into films, and then R 2 or R 2And M are absorbed by the sintered body; characterized in that a jig is used to arrange the plurality of sintered bodies side by side such that the first surface of the plurality of sintered bodies is along a plane parallel to the vertical direction or the horizontal direction, and in the grain boundary diffusion process, on the first surface side of the plurality of sintered bodies, there is arranged a target containing the R 2 and on the second surface side of the plurality of sintered bodies, there is arranged a target containing the R 2 In a dual-sided film-forming processing chamber with a target on the first surface side of the plurality of sintered bodies arranged side by side using the jig and a target on the second surface side of the plurality of sintered bodies arranged side by side using the jig, the film is simultaneously formed on the first surface and the second surface of the plurality of sintered bodies arranged side by side using the jig in an inert gas atmosphere.

[0025] (4) The method for preparing a rare earth magnet according to (3), characterized in that the dual-sided film-forming processing chamber is formed by connecting a plurality of film-forming processing chambers in series, and the plurality of sintered bodies are continuously formed into films in an inert gas atmosphere without being exposed to the atmosphere.

[0026] (5) The method for preparing a rare earth magnet according to any one of (1) to (4), characterized in that the jig is made of one or more materials selected from aluminum, aluminum alloy, copper, copper alloy, iron, iron alloy, titanium, titanium alloy, niobium, niobium alloy, tungsten, tungsten alloy, molybdenum, and molybdenum alloy, and the jig is configured to clamp the sintered body and hold it in a holding portion with a sharp front end, and the moving distance of the front end of the holding portion within the elastic limit is more than twice the dimensional tolerance range of the dimension in the clamping direction of the sintered body.

[0027] (6) The method for preparing a rare earth magnet according to any one of (1) to (5), characterized in that the portion of the holding portion other than the contact point with the sintered body and the electrical connection point for grounding is coated with one or more materials selected from organic substances and ceramics.

[0028] (7) The method for preparing a rare earth magnet according to any one of (1) to (6), characterized in that the grain boundary diffusion step includes one or more than two steps selected from the following: an atmosphere vacuum step of evacuating the atmosphere of the plurality of sintered compacts in a preparation chamber before putting the plurality of sintered compacts into the film forming treatment chamber; an adsorbed gas dissociation step of dissociating the adsorbed gas from the plurality of sintered compacts in a baking treatment chamber before putting the plurality of sintered compacts into the film forming treatment chamber; a surface cleaning step of cleaning the surfaces of the plurality of sintered compacts in a reverse sputtering chamber before putting the plurality of sintered compacts into the film forming treatment chamber; a heat treatment step of heat-treating the plurality of sintered compacts in a heat treatment chamber after forming the film on the surfaces of the plurality of sintered compacts; a cooling step of cooling the heat-treated plurality of sintered compacts in a cooling chamber; and an atmosphere opening step of making the atmosphere of the plurality of sintered compacts at atmospheric pressure in order to open the plurality of sintered compacts to the atmosphere in an extraction chamber; the film forming treatment chamber is continuously connected to one or more than two chambers selected from the preparation chamber, the baking treatment chamber, the heat treatment chamber, the cooling chamber, and the extraction chamber.

[0029] (8) The method for preparing a rare earth magnet according to any one of (1) to (7), characterized in that the grain boundary diffusion step includes the following welding suppression step: after the film formation and before the heat treatment, one or more than two compounds selected from oxides, fluorides, and oxyfluorides of R 3 (R 3 is one or more than two elements selected from rare earth elements) are formed on one or both of the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig; in the welding suppression step, in a welding suppression treatment chamber provided with a target composed of one or more than two materials selected from metals of R 3 , alloys of R 3 , oxides of R 3 , fluorides of R 3 , and oxyfluorides of R 3 arranged on the first surface side of the plurality of sintered compacts and a target composed of one or more than two materials selected from metals of R 3 , alloys of R 3 , oxides of R 3 , fluorides of R 3 , and oxyfluorides of R 3 arranged on the second surface side of the plurality of sintered compacts, the compound is formed on one or both of the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig in an atmosphere of one or more than two gases selected from argon, oxygen, and nitrogen.

[0030] (9) The method for preparing a rare earth magnet according to (8), wherein the welding suppression step includes: a first welding suppression step, in a first welding suppression processing chamber provided with the target disposed on the first surface side of the plurality of sintered bodies, forming a film of the compound on the first surface of the plurality of sintered bodies arranged in parallel using the jig by physical vapor deposition; and a second welding suppression step, in a second welding suppression processing chamber provided with the target disposed on the second surface side of the plurality of sintered bodies, forming a film of the compound on the second surface of the plurality of sintered bodies arranged in parallel using the jig by physical vapor deposition.

[0031] (10) The method for preparing a rare earth magnet according to (8), wherein in the welding suppression step, in a double-sided welding suppression processing chamber provided with the target disposed on the first surface side of the plurality of sintered bodies and the target disposed on the second surface side of the plurality of sintered bodies, forming a film of the compound on the first surface and the second surface of the plurality of sintered bodies arranged in parallel using the jig simultaneously by physical vapor deposition.

[0032] (11) The method for preparing a rare earth magnet according to any one of (1) to (7), wherein the physical vapor deposition method is a sputtering method.

[0033] (12) The method for preparing a rare earth magnet according to any one of (8) to (10), wherein the physical vapor deposition method in the welding suppression step is an RF sputtering method.

[0034] Effects of the Invention

[0035] According to the present invention, high-performance rare earth magnets can be prepared stably and in large quantities by using the grain boundary diffusion method of a film formed by physical vapor deposition. Description of the Drawings

[0036] Figure 1 Figure 1 is a schematic view of a first film formation processing chamber used in the method for preparing a rare earth magnet according to an embodiment of the present invention in a case where the magnets are arranged left and right as viewed from above in the vertical direction.

[0037] Figure 2 Figure 2 is a schematic view of a first film formation processing chamber used in the method for preparing a rare earth magnet according to an embodiment of the present invention in a case where the magnets are arranged up and down as viewed from the side in the horizontal direction.

[0038] Figure 3 Figure 3 ​​​It is a schematic diagram of the first film-forming processing chamber and the second film-forming processing chamber used in the method for preparing a rare-earth magnet according to an embodiment of the present invention when viewed from above in the vertical direction with a left-right arrangement.

[0039] Figure 4 Figure 4 It is a schematic diagram of the first film-forming processing chamber and the second film-forming processing chamber used in the method for preparing a rare-earth magnet according to an embodiment of the present invention when viewed from the side in the horizontal direction with an up-down arrangement.

[0040] Figure 5 Figure 5 It is a schematic diagram of a sintered body support jig configured with a sintered body used in the method for preparing a rare-earth magnet according to an embodiment of the present invention with a left-right arrangement.

[0041] Figure 6 Figure 6 It is a schematic diagram of a sintered body support jig configured with a sintered body used in the method for preparing a rare-earth magnet according to an embodiment of the present invention with an up-down arrangement.

[0042] Figure 7 Figure 7 It is Figure 5 a cross-sectional view of the A-A' portion of the sintered body support jig shown.

[0043] Figure 8 Figure 8 It is Figure 6 a cross-sectional view of the A-A' portion of the sintered body support jig shown.

[0044] Figure 9 Figure 9 It is a schematic diagram of a configuration example of the first film-forming processing chamber and the second film-forming processing chamber used in the method for preparing a rare-earth magnet according to an embodiment of the present invention when viewed from above in the vertical direction with a left-right arrangement.

[0045] Figure 10 Figure 10 It is a schematic diagram of a configuration example of the first film-forming processing chamber and the second film-forming processing chamber used in the method for preparing a rare-earth magnet according to an embodiment of the present invention when viewed from the side in the horizontal direction with an up-down arrangement.

[0046] Figure 11 Figure 11 It is a schematic diagram of a double-sided film-forming processing chamber used in the method for preparing a rare-earth magnet according to an embodiment of the present invention when viewed from above in the vertical direction with a left-right arrangement.

[0047] Figure 12 Figure 12 ​​​​​​​​​It is a schematic diagram of a double-sided film-forming treatment chamber used in the method for preparing a rare-earth magnet according to an embodiment of the present invention when viewed laterally from the horizontal direction with the components arranged one above the other. Detailed Embodiments

[0048] Hereinafter, the present invention will be described in more detail.

[0049] The present invention relates to a method for preparing a rare-earth magnet with high performance and a small amount of Tb or Dy used. The method for preparing a rare-earth magnet according to an embodiment of the present invention includes the following grain boundary diffusion process: on a plurality of sintered compacts composed of an R 1 -Fe-B system composition (R 1 is one or more elements selected from rare-earth elements, and one or two of Pr and Nd are essential), and each having a first surface and a second surface opposite to the first surface, by physical vapor deposition, one or more films selected from R 2 film, R 2 -M alloy film, and a multilayer film of R 2 and M (R 2 is one or more elements selected from rare-earth elements, and one or two of Tb and Dy are essential, and M is one or more elements selected from Cu, Al, Co, Fe, Mn, Ni, Sn, and Si) are formed, and then through heat treatment, R 2 or R 2 and M are absorbed by the sintered compact. Here, the sintered compact can be obtained by coarsely pulverizing, finely pulverizing, forming, and sintering the master alloy according to a conventional method.

[0050] In this case, the master alloy contains R 1 , T, Q, and B. R 1 is one or more elements selected from rare-earth elements, and one or two of Pr and Nd are essential. Specifically, among rare-earth elements, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu can be listed, and R 1 is mainly composed of one or two of Pr and Nd. R 1 is preferably 12 to 17 atomic% of the total alloy, particularly preferably 13 to 17 atomic%, and further preferably in R 1 relative to all R 1It is suitable to contain 80 atomic % or more, especially 85 atomic % or more of Pr and Nd or any one of them. T is Fe, or Fe and Co. When T is Fe and Co, it is preferable to contain Fe at 85 atomic % or more, especially 90 atomic % or more in T. Regarding Q, one or more elements selected from Al, Si, Cu, Zn, In, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, and W can be contained at 0 to 10 atomic %, especially 0.05 to 4 atomic %. It is preferable to contain B at 5 to 10 atomic %, especially 5 to 7 atomic % of the total alloy. The balance is inevitable impurity elements such as C, N, O, and F.

[0051] The master alloy is obtained by melting the raw material metal or alloy in a vacuum or an inert gas, preferably in an Ar atmosphere, and then casting it into a flat mold or a book-shaped mold, or by strip casting. Additionally, the so-called double alloy method can also be applied, that is, alloys with compositions close to the main phase of the master alloy, namely R 1 2 Fe 14 B compound, and an R-rich alloy that becomes a liquid-phase sintering aid at the sintering temperature 1 or R-rich 2 alloy are weighed and mixed after coarse crushing.

[0052] However, for alloys with compositions close to the main phase, depending on the cooling rate during casting or the alloy composition, primary α-Fe is likely to remain in the master alloy. Therefore, in order to increase the amount of the R 1 2 Fe 14 B compound phase, homogenization treatment is carried out as needed. For example, the master alloy is heat-treated in a vacuum or an Ar atmosphere at a heat treatment temperature of 700 to 1,200 °C for 1 hour or more. Additionally, for the R-rich 1 or R-rich 2 alloy that becomes a liquid-phase sintering aid, in addition to the above casting method, it can also be produced by the so-called liquid quenching method.

[0053] The above master alloy is usually coarsely crushed to 0.05 to 3 mm, especially 0.05 to 1.5 mm. In the coarse crushing process, a Braun mill or hydrogen crushing is used, and hydrogen crushing is preferred in the case of a master alloy produced by strip casting. The coarse powder is usually finely crushed to 0.1 to 30 μm, especially 0.2 to 20 μm, by using a jet mill with high-pressure nitrogen.

[0054] The obtained fine powder is formed into a compact by a compression molding machine in a magnetic field and then put into a sintering furnace. The sintering is carried out in a vacuum or inert gas atmosphere at a sintering temperature generally of 900 to 1,250 °C, particularly 1,000 to 1,100 °C. The obtained sintered body contains 60 to 99% by volume, particularly preferably 80 to 98% by volume, of tetragonal R 1 2 Fe 14 B compound as the main phase. The balance is composed of 0.5 to 20% by volume of an R 1 -rich phase (containing more than 25 atomic% of R 1 ), 0 to 10% by volume of a B-rich phase, and 0.1 to 10% by volume of one or more compounds or a mixture or complex of phases selected from oxides of R 1 and carbides, nitrides, hydroxides, and fluorides formed from inevitable impurities.

[0055] After the obtained sintered body is ground into a specified shape as required, the following grain boundary diffusion process is carried out: By physical vapor deposition (PVD), one or more films selected from R 2 film, R 2 -M alloy film, and a multilayer film of R 2 and M (R 2 is one or more elements selected from rare earth elements, one or two of Tb and Dy are essential, and M is one or more elements selected from Cu, Al, Co, Fe, Mn, Ni, Sn, and Si) are formed on the surface of the sintered body, and R 2 or R 2 and M are absorbed by the sintered body through subsequent heat treatment. It should be noted that the shape of the sintered body is preferably a plate shape. In addition, it may also be the case of forming a multilayer film by separately forming R 2 and M, or the case of simultaneously forming R 2 and M and alloying R 2 and M at this time.

[0056] The size of the sintered body is not particularly limited. However, in the grain boundary diffusion process, if the film thickness of the R 2 film, the R 2 -M alloy film, or the multilayer film of R 2 and M is constant, the larger the specific surface area of the sintered body, that is, the smaller the size, the more R 2The more. Therefore, from the viewpoint of the coercive force finally obtained, i.e., heat resistance, the size of the smallest part of the sintered body shape is preferably 30 mm or less, more preferably 15 mm or less. It should be noted that the lower limit of the size of the above-mentioned smallest part is not particularly limited and can be appropriately selected, but the size of the smallest part of the above-mentioned shape is preferably 0.5 mm or more.

[0057] As the grain boundary diffusion process, first, by PVD method, on the surface of the sintered body, one or more films selected from R 2 film, R 2 -M alloy film, and a multilayer film of R 2 and M are formed. Here, the sputtering method, which is one of the representative PVD methods, is exemplified.

[0058] In the preparation method according to an embodiment of the present invention, for example, when the target and the sintered body are arranged such that the first surface of the sintered body is parallel to the vertical plane, as Figure 1 and Figure 5 shown, for a plurality of sintered bodies 7 each having a first surface 21 and a second surface 22 on the opposite side of the first surface 21, the plurality of sintered bodies 7 are arranged side by side using a sintered body support jig 6 in a manner along a plane 23 parallel to the first surface 21 of the plurality of sintered bodies 7. On the other hand, when the target and the sintered body are arranged such that the first surface of the sintered body is parallel to the horizontal plane, as Figure 2 and Figure 6 shown, for a plurality of sintered bodies 7 each having a first surface 21 and a second surface 22 on the opposite side of the first surface 21, the plurality of sintered bodies 7 are arranged side by side using a sintered body support jig 6 in a manner along a plane 23 parallel to the first surface 21 of the plurality of sintered bodies 7. Conventionally, since the target is arranged above in the vertical direction and the sintered body is placed on a tray arranged below the target, only the first surface 21 on the target side can be coated with a film; by using this sintered body support jig 6, the second surface 22 on the opposite side of the first surface 21 can also be coated with a film. Thus, even without placing on the tray, a plurality of sintered bodies can be arranged side by side. It should be noted that, as Figure 1 shown, the case where the target and the sintered body are arranged such that the first surface of the sintered body is parallel to the vertical plane is hereinafter referred to as the left-right arrangement; as Figure 2 shown, the case where the target and the sintered body are arranged such that the first surface of the sintered body is parallel to the horizontal plane is hereinafter referred to as the up-down arrangement.

[0059] In the case where a target 4 containing R 2 is arranged on the first surface 21 side of a plurality of sintered bodies 7 (for example, made of R 2 , R 2 -M alloy, or R 2In the first film-forming treatment chamber 5 of the target 4 composed of R and M, a plurality of sintered compacts 7 arranged in parallel using a sintered compact support jig 6 are disposed. It should be noted that a cathode 2 is provided on the side opposite to the sintered compact side of the target 4. In addition, an anode 3 is provided on the side opposite to the target side of the plurality of sintered compacts 7. Figure 1 and Figure 2 are schematic views of the first film-forming treatment chamber 5 when viewed from above in the vertical direction and from the side in the horizontal direction, respectively. Depending on the size of each target, by R 2 、R 2 -M alloy or R 2 and M, the target 4 is composed of one target or a plurality of targets. The target 4 is fixed to the cathode 2, for example, by a backing plate (not shown). In addition, while moving a plurality of sintered compacts arranged in parallel using the sintered compact support jig 6 continuously along the Figure 3 and Figure 4 indicated traveling direction, when film-forming is performed in an inert atmosphere without being exposed to the atmosphere, a plurality of sintered compact support jigs 6 provided with the sintered compacts 7 can be arranged in series in parallel along the traveling direction of the sintered compact support jig 6. It should be noted that the target 4 is arranged so as to face the first surface 21 of the plurality of sintered compacts 7, but as long as it is arranged on the first surface 21 side of the plurality of sintered compacts 7, there is no particular limitation on the arrangement of the target. For example, in the case of the opposed target sputtering method, the target may be arranged so as not to face the first surface of the plurality of sintered compacts. In addition, the shape of the target 4 is flat, but there is no particular limitation on the shape of the target. For example, in the case of the magnetron sputtering method, a cylindrical target can be used.

[0060] In the first film-forming treatment chamber 5, on the first surface 21 of the sintered compact, one or more films selected from the group consisting of R 2 film, R 2 -M alloy film, and a multilayer film of R 2 and M are formed. Then, as Figure 3 and Figure 4 shown, the sintered compact support jig 6 provided with a plurality of sintered compacts 7 is moved in the horizontal direction. Then, the sintered compact support jig 6 is moved to the second film-forming treatment chamber 25 provided adjacent to the first film-forming treatment chamber 5 and having the target 4 containing R 2 arranged on the second surface 22 side opposite to the first surface 21. Then, the above-mentioned film is formed on the second surface 22 of the sintered compact 7. The first film-forming treatment chamber 5 and the second film-forming treatment chamber 25 are continuously connected in such a way that the sintered compact 7 does not come into contact with the atmosphere, as Figure 9 and Figure 10As shown, it can be configured in series by multiple film-forming treatment chambers as needed. It should be noted that in the case where the target and the sintered body are arranged left and right, the second film-forming treatment chamber can be arranged in the vertical direction of the first film-forming treatment chamber, so that the sintered body support jig on which multiple sintered bodies are arranged moves in the vertical direction. Thus, multiple sintered bodies can be continuously film-formed in an inert gas atmosphere without being exposed to the atmosphere. It should be noted that the target 4 is arranged to face the second surface 22 of the multiple sintered bodies 7, but as long as it is arranged on the second surface 22 side of the multiple sintered bodies 7, there is no special limitation on the arrangement of the target. For example, in the case of the opposed target sputtering method, the target can be arranged in a manner that does not face the second surface of the multiple sintered bodies.

[0061] The sputtering method is carried out in an inert gas atmosphere of about several Pa, preferably an argon atmosphere. As the power supply 1 used in the sputtering method, a DC power supply is preferred, but it can also be an RF power supply or a combination thereof.

[0062] Before the film-forming treatment chamber 5 for film formation, a preparation chamber via a gate valve is preferably provided, and the gate valve separates the inside of the film-forming treatment chamber from the atmosphere. In the preparation chamber, the sintered body support jig 6 on which multiple sintered bodies 7 are arranged is loaded, and after closing the front and rear gate valves, vacuum pumping is started. After reaching a high vacuum atmosphere, an inert gas, preferably argon, is introduced to replace the atmosphere in the chamber. In addition, before the film-forming treatment chamber 5 for film formation, a baking treatment chamber for dissociating adsorbed gases such as water or oxygen on the surface of the sintered body from the sintered body, or a reverse sputtering treatment chamber for cleaning the surface of the sintered body by sputtering the surface of the sintered body with the sintered body as the cathode can be provided. In addition, the above treatment can also be carried out in the preparation chamber by providing the above treatment equipment in the preparation chamber.

[0063] Regarding the thickness of the film formed on the surface of the sintered body 7, it can be appropriately determined according to the amount of R 2 (the increased amount of the coercive force desired to be obtained) that is desired to be absorbed by the sintered body 7. However, from the viewpoints of obtaining a sufficient coercive force increasing effect, the time required for the treatment, productivity, and resource saving, the thickness of the film is typically 0.1 to 50 μm, preferably 0.5 to 20 μm, and more preferably 1 to 10 μm.

[0064] In Figures 5 - 8 a schematic example of the sintered body support jig 6 is shown. In the case of left and right arrangement, as Figure 5 shown, the multiple sintered bodies 7 are arranged in parallel using the sintered body support jig 6 such that the first surface 21 of the multiple sintered bodies 7 is along a plane parallel to the vertical direction. On the other hand, in the case of up and down arrangement, as Figure 6As shown, within the plane of the first surface 21 of the plurality of sintered compacts 7 that is parallel to the horizontal direction, the plurality of sintered compacts 7 are arranged side by side using the sintered compact support jig 6. The sintered compacts 7 are clamped and held by the holding portions 17 and 18 formed at the front ends of the sintered compact support jig 6 and shaped to be sharp. Therefore, the sintered compact support jig 6 needs to have sufficient strength relative to the weight of the sintered compact, and the holding portions need to have the ability of elastic deformation. From this perspective, as the material of the sintered compact support jig 6, for example, one or more materials selected from aluminum, aluminum alloy, copper, copper alloy, iron, iron alloy, titanium, titanium alloy, niobium, niobium alloy, tungsten, tungsten alloy, molybdenum, and molybdenum alloy are preferably used.

[0065] In addition, when the sintered compact support jig 6 and the sintered compact 7 are used as anodes, especially when applying the above-mentioned simultaneous film formation on both sides (refer to Figure 11 and Figure 12 ), electrical conductivity is required between the sintered compact support jig 6 and the sintered compact 7. Thus, in order to ensure conductivity, the front ends 17 and 18 of the holding portions are shaped to be sharp. It should be noted that when the sintered compact support jig 6 and the sintered compact 7 are used as anodes, the front ends 17 and 18 of the holding portions are not only the contact points with the sintered compact 7 but also become the electrical connection points for grounding. Regarding the portions of the sintered compact support jig 6 other than these front ends 17 and 18, in order to suppress unnecessary film formation on the sintered compact support jig caused by the sputtering method or to make the portions with unnecessary film formation in a state that is easy to clean, it is appropriate to coat with one or more materials selected from organic substances such as epoxy resin and ceramics such as alumina.

[0066] Furthermore, the holding portions of the sintered compact support jig 6 have the ability of elastic deformation to clamp the sintered compact 7, causing the front ends 17 and 18 to move up and down or left and right. In order to sufficiently clamp the dimensions in the clamping direction of the sintered compact 7, the holding portions need to elastically deform to the extent of the dimensional tolerance of the sintered compact 7. For example, when the tolerance range is 0.4 mm, the tolerance range of the front end movement distance caused by elastic deformation is also designed to be about 0.4 mm. However, regarding the application range of such a sintered compact support jig 6, the sintered compact support jig 6 can only be applied to the case where the clamping direction dimension of the sintered compact 7 is the same as the tolerance range. Therefore, if it is desired to apply it to rare earth magnet products finally processed into various shapes and sizes, the types of the sintered compact support jig 6 become numerous, which is unreasonable.

[0067] Therefore, the sintered body support jig 6 for the sintered body 7 that can be applied to a certain size range regardless of the type of rare earth magnet products is effective. In the present invention, considering the actual material physical property values and the design range of the sintered body support jig 6, the moving distance of the front ends 17 and 18 of the holding part within the elastic limit of the holding part can be made more than twice the dimensional tolerance range of the dimension of the sintered body 7 in the clamping direction. By using such a sintered body support jig 6, the types of sintered body support jigs 6 to be prepared can be significantly reduced. For example, if a sintered body support jig 6 with a moving distance of the front end of the holding part within the elastic limit that is twice the dimensional tolerance range of 0.4 mm of the dimension of the sintered body 7 in the clamping direction is used, the sintered body 7 with a difference in the clamping direction dimension of 0.8 mm can be processed with the same sintered body support jig 6.

[0068] As the holding part of the sintered body support jig having elastic deformation ability, for example, when arranged left and right, it can adopt the form as shown in Figure 7 ; when arranged up and down, it can adopt the form as shown in Figure 8 . The beam 15 of the holding part elastically deforms around the crossbeam 16, causing the front end 17 of the holding part to move upward and the front end 18 of the holding part to move downward. Thus, the holding part can have a larger front end moving distance relative to the dimensional tolerance range of the sintered body 7. Thereby, for the sintered body 7 with various dimensional tolerance ranges, the types of sintered body support jigs 6 to be prepared can be reduced, and multiple sintered bodies 7 can be held at once. Thereby, the film forming process can be effectively implemented. In addition, by also selecting a material and size with elastic deformation ability for the crossbeam 16, a displacement amount larger than the elastic limit of the beam 15 can be given to the front ends 17 and 18.

[0069] To improve the productivity of the film forming process, it is more appropriate to perform film forming on the first surface and the second surface of the sintered body simultaneously. In this case, since the sintered body is used as the anode, electrical conduction is important. For example, when arranged left and right as shown in Figure 11 , and when arranged up and down as shown in Figure 12 , two targets 4 are arranged in the double-sided film forming treatment chamber 35 in a manner that sandwiches the sintered body support jig 6 with the sintered body 7 arranged therein. It should be noted that even in such a case of simultaneous double-sided film forming, the double-sided film forming treatment chamber 35 can be arranged in series with multiple film forming treatment chambers as needed, so that multiple sintered bodies are not exposed to the atmosphere and film forming can be continuously performed in an inert gas atmosphere. In addition, the double-sided film forming treatment chamber 35 can be connected and arranged with one or more than two of the first film forming treatment chamber 5 and the second film forming treatment chamber 25. It should be noted that in the double-sided film forming treatment chamber 35, a target 4 containing R 2 is arranged on the first surface 21 side of multiple sintered bodies 7, and a target 4 containing R 2The target 4. Further, in the double-sided film-forming processing chamber 35, a film is formed on the first surface 21 and the second surface 22 of a plurality of sintered compacts 7 arranged in parallel using the sintered compact support jig 6 in an inert gas atmosphere.

[0070] In the heat treatment for diffusion described later, the sintered compacts on which the film has been formed can be put into the heat treatment chamber. However, if they are simply overlapped and put in, there is a case where the film-formed surfaces are welded during the heat treatment. When the melting point of the diffusion source is lower than the diffusion treatment temperature, it completely melts, and the overlapping sintered compacts are welded to each other during the cooling process. Even when the melting point of the diffusion source is high, it is common to react with the sintered compact and as a result, a low-melting point phase is formed, and welding also occurs in this case. To avoid this, it is preferable to use a jig in which the sintered compacts do not contact each other when put into the heat treatment chamber. However, the isolation caused by the jig reduces the amount of sintered compacts put into the heat treatment chamber. From the viewpoint of productivity, it is important not to reduce the input amount as much as possible.

[0071] In this case, for example, an R 3 (R 3 is one or more elements selected from rare earth elements) oxide, fluoride, oxyfluoride, etc. rare earth compound film is formed on the outermost surface layer of the film-forming surface of the sintered compact. Thereby, welding during heat treatment of the sintered compacts in an overlapped state can be suppressed. If the film formation for this purpose is carried out by the sputtering method of other processes, the productivity is reduced. Therefore, it is preferable to continuously form the above rare earth compound film after forming the diffusion source film. In this case, by providing a welding suppression processing chamber for forming the above rare earth compound film adjacent to the processing chamber for sputtering the diffusion source, the processing can be continuously carried out without reducing the productivity. As the target provided in the welding suppression processing chamber, a target composed of one or more materials selected from R 3 (R 3 is one or more elements selected from rare earth elements) metal, R 3 alloy, R 3 oxide, R 3 fluoride, and R 3 oxyfluoride is suitable.

[0072] In addition, for example, by using a target of R 3 metal or R 3 fluoride, the atmosphere in the welding suppression processing chamber is made to have an oxygen or nitrogen partial pressure to form reactive sputtering. Moreover, an oxide film can be formed by the combination of a metal target and an oxygen atmosphere, a nitride film can be formed by the combination of a metal target and a nitrogen atmosphere, and a film such as an oxyfluoride can be formed by the combination of a fluoride target and an oxygen atmosphere. These films are also highly effective in preventing welding.

[0073] As the film thickness of the film of the rare earth compound described above, an effect can be observed when it is 10 nm or more, but preferably 100 nm or more. There is no upper limit set for the film thickness, but if the productivity is not reduced, it can be formed to about 100 μm. In addition, when using a target of a rare earth compound with low conductivity, the power supply is preferably an RF power supply.

[0074] When setting such a film of the rare earth compound, similar to the film formation processes in the above-mentioned first film formation processing chamber 5 and second film formation processing chamber 25, for example, a first welding suppression processing chamber for forming the rare earth compound on the first surface of the sintered body and a second welding suppression processing chamber for forming the rare earth compound on the second surface of the sintered body can be set. In addition, similar to the film formation process in the above-mentioned double-sided film formation processing chamber 35, for example, in a welding suppression processing chamber equipped with both a target arranged on the first surface side of the sintered body and a target arranged on the second surface side of the sintered body, the rare earth compound can be formed on both the first surface and the second surface of the sintered body simultaneously.

[0075] Due to a series of film formation processes, the sintered body mostly reaches a high temperature, so a cooling chamber can be set after the film formation processing chamber. When using argon or the like during cooling, a gate valve can be set between it and the film formation processing chamber. In addition, it is preferable to set an extraction chamber for extracting the sintered body on which the film is formed via a gate valve at the very end.

[0076] Then, for example, the sintered body is taken out from the sintered body support jig output from the device and put into a heat treatment chamber, and heat treatment (this treatment will be referred to as diffusion treatment later) is performed in a vacuum or an inert gas atmosphere such as argon or helium. The diffusion treatment temperature is below the sintering temperature of the sintered body. The reason for limiting the diffusion treatment temperature is as follows. That is, if heat treatment is performed at a temperature higher than the sintering temperature (referred to as T S ℃) of the sintered body, the following problems will occur: (1) the structure of the sintered body deteriorates and high magnetic properties cannot be obtained, (2) the processed dimensions cannot be maintained due to thermal deformation, (3) R 2 diffuses not only to the grain boundaries of the sintered body but also excessively into the grain interiors, resulting in a decrease in the residual magnetic flux density, etc.; therefore, the diffusion treatment temperature is set below the sintering temperature, preferably (T S -10) °C or lower. It should be noted that the lower limit of the diffusion treatment temperature can be appropriately selected, usually 600 °C or higher. From the viewpoints of fully completing the diffusion treatment and considering the deterioration of the sintered body structure and the influence on magnetic properties, the diffusion treatment time is 1 minute to 100 hours, more preferably 30 minutes to 50 hours, and particularly preferably 1 hour to 30 hours.

[0077] Through the diffusion treatment as described above, R 2 is concentrated in the R 1 -rich grain boundary phase composition in the sintered body, and this R2 In R 1 2 Fe 14 part of R is replaced near the surface layer of the main phase particles of B. Elements that have a particularly large effect of enhancing the crystalline magnetic anisotropy by concentrating in the above surface layer are Tb and Dy. Therefore, it is appropriate that the total proportion of Tb and / or Dy in the rare earth element R contained in the diffusion source is 50 atomic% or more, and more preferably 80% or more. In addition, when one or both of Pr and Nd are contained in the R contained in the diffusion source, it is preferable that the total concentration of Pr and Nd in the R contained in the diffusion source is lower than the total concentration of Pr and Nd in the rare earth element R contained in the base material. As a result of this diffusion treatment, the coercive force of the R 1 -Fe-B-based sintered magnet is effectively increased, and there is almost no decrease in the residual magnetic flux density. 2 In addition, when an R 2 -M alloy film or a multilayer film of R 2 and M is formed on the surface of the sintered body, an R 1 -Fe-M phase can be formed in the grain boundary phase by the diffusion treatment as described above. Thereby, the coercive force of the R 1 -Fe-B-based sintered magnet can be further increased.

[0078] In addition, it is preferable to perform a heat treatment at a low temperature (this treatment will be referred to as an aging treatment hereinafter) after the diffusion treatment. As the treatment temperature of this aging treatment, it is desired to be lower than the diffusion treatment temperature, preferably 200 °C or higher and lower than the diffusion treatment temperature by 10 °C or lower, and more preferably 350 °C or higher and lower than the diffusion treatment temperature by 10 °C or lower. In addition, the atmosphere of the aging treatment is preferably in a vacuum or an inert gas such as argon or helium. The treatment time of the aging treatment is 1 minute to 10 hours, preferably 10 minutes to 5 hours, and particularly preferably 30 minutes to 2 hours. 2 -M alloy film or a multilayer film of R 2 and M is formed on the surface of the sintered body, an R 2 -Fe-M phase can be formed in the grain boundary phase by the diffusion treatment as described above. Thereby, the coercive force of the R 1 -Fe-B-based sintered magnet can be further increased.

[0079] In addition, it is preferable to perform a heat treatment at a low temperature (this treatment will be referred to as an aging treatment hereinafter) after the diffusion treatment. As the treatment temperature of this aging treatment, it is desired to be lower than the diffusion treatment temperature, preferably 200 °C or higher and lower than the diffusion treatment temperature by 10 °C or lower, and more preferably 350 °C or higher and lower than the diffusion treatment temperature by 10 °C or lower. In addition, the atmosphere of the aging treatment is preferably in a vacuum or an inert gas such as argon or helium. The treatment time of the aging treatment is 1 minute to 10 hours, preferably 10 minutes to 5 hours, and particularly preferably 30 minutes to 2 hours.

[0080] It should be noted that during the above grinding process before the diffusion treatment, when an aqueous coolant is used in the coolant of the grinding machine or when the grinding surface is exposed to a high temperature during processing, an oxide film is likely to be generated on the ground surface. If it is mild, a clean surface can be obtained before the diffusion treatment by the above baking treatment or reverse sputtering treatment before film formation by the sputtering method. However, when an excessive oxide film is formed on the surface of the sintered body, this oxide film will hinder R 2Diffusion into the sintered body. In this case, by cleaning or performing shot peening using one or more compounds selected from alkalis, acids, and organic solvents to remove the oxide film, a proper diffusion treatment can be carried out thereafter.

[0081] Examples of the alkali used to remove the oxide film include potassium pyrophosphate, sodium pyrophosphate, potassium citrate, sodium citrate, potassium acetate, sodium acetate, potassium oxalate, sodium oxalate, etc. In addition, examples of the acid used to remove the oxide film include hydrochloric acid, nitric acid, sulfuric acid, acetic acid, citric acid, tartaric acid, etc. Furthermore, examples of the organic solvent used to remove the oxide film include acetone, methanol, ethanol, isopropyl alcohol, etc. In this case, the above-mentioned alkali or acid can be used in the form of an aqueous solution with a concentration that does not corrode the sintered body.

[0082] In addition, for the sintered body that has undergone the above-mentioned diffusion treatment or subsequent aging treatment, it can also be cleaned with one or more compounds selected from alkalis, acids, and organic solvents, or ground into a practical shape. Furthermore, plating or coating can be carried out after such diffusion treatment, aging treatment, cleaning, or grinding.

[0083] Above, taking the film-forming treatment chambers 5, 25, and 35 as examples, a method for preparing a rare-earth magnet according to an embodiment of the present invention has been described. However, as long as the method for preparing a rare-earth magnet of the present invention can be implemented, the film-forming apparatus used in the method for preparing a rare-earth magnet of the present invention is not limited to the film-forming treatment chambers 5, 25, and 35.

[0084] The rare-earth magnet obtained as described above can be used as a high-performance permanent magnet with an increased coercive force.

[0085] Symbol Explanation

[0086] 1 Power supply

[0087] 2 Cathode

[0088] 3 Anode

[0089] 4 Target

[0090] 5, 25, 35 Film-forming treatment chambers

[0091] 6 Sintered body support jig

[0092] 7 Sintered body

[0093] 15 Beam of the holding part

[0094] 16 Cross beam

[0095] 17, 18 Front ends of the holding part

[0096] 21 First surface

[0097] Side 22

Claims

1. A method for preparing a rare earth magnet, comprising the following grain boundary diffusion step: on a plurality of sintered compacts composed of an R 1 -Fe-B system composition and having a first surface and a second surface opposite to the first surface, respectively, by physical vapor growth method, a film selected from an R 2 film, an R 2 -M alloy film, and a multilayer film of R 2 and M is formed, and then R 2 or R 2 and M are absorbed by the sintered compact; R 1 is one or more elements selected from rare earth elements, and one or two of Pr and Nd are essential, R 2 is one or more elements selected from rare earth elements, wherein one or two of Tb and Dy are essential, M is one or more elements selected from Cu, Al, Co, Fe, Mn, Ni, Sn and Si, It is characterized in that a fixture is used to arrange the plurality of sintered compacts side by side such that the first surface of the plurality of sintered compacts is along a plane parallel to the vertical direction or the horizontal direction, The grain boundary diffusion process includes: a first film forming process of forming a film on a first surface of the plurality of sintered compacts arranged side by side using the jig in a first film forming chamber provided with a target containing the R 2 in an inert gas atmosphere; a second film forming process of forming a film on a second surface of the plurality of sintered compacts arranged side by side using the jig in a second film forming chamber provided with a target containing the R 2 and arranged side by side with the first film forming chamber in an inert gas atmosphere; and a moving process of moving the plurality of sintered compacts arranged side by side using the jig between the first film forming chamber and the second film forming chamber in a horizontal direction or a vertical direction, the fixture is made of one or more materials selected from aluminum, aluminum alloy, copper, copper alloy, iron, iron alloy, titanium, titanium alloy, niobium, niobium alloy, tungsten, tungsten alloy, molybdenum and molybdenum alloy, the fixture is configured to hold the sintered compact in a holding portion with a sharpened front end, the moving distance of the front end of the holding portion within the elastic limit is more than twice the dimensional tolerance range of the dimension of the sintered compact in the clamping direction.

2. The method for preparing a rare earth magnet according to claim 1, It is characterized in that the first film-forming treatment chamber and the second film-forming treatment chamber are respectively formed by arranging a plurality of film-forming treatment chambers in series, and the plurality of sintered compacts are continuously film-formed in an inert gas atmosphere without being exposed to the atmosphere.

3. Method for preparing rare earth magnet, comprising the following grain boundary diffusion step: On a plurality of sintered compacts composed of an R 1 -Fe-B system composition and having a first surface and a second surface opposite to the first surface respectively, by physical vapor growth method, a film selected from an R 2 film, an R 2 -M alloy film and a multilayer film of R 2 and M is formed, and R 2 or R 2 and M are absorbed by the sintered compact through subsequent heat treatment; R 1 is one or more elements selected from rare earth elements, and one or two of Pr and Nd are essential, R 2 is one or more elements selected from rare earth elements, wherein one or two elements of Tb and Dy are essential, and M is one or more elements selected from Cu, Al, Co, Fe, Mn, Ni, Sn, and Si. It is characterized in that a fixture is used to arrange the plurality of sintered compacts side by side such that the first surface of the plurality of sintered compacts is along a plane parallel to the vertical direction or the horizontal direction, In the grain boundary diffusion process, in a dual-sided film-forming processing chamber provided with a target containing the R disposed on the first surface side of the plurality of sintered compacts and a target containing the R disposed on the second surface side of the plurality of sintered compacts, the film is simultaneously formed on the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig in an inert gas atmosphere. 2 In the grain boundary diffusion process, in a dual-sided film-forming processing chamber provided with a target containing the R disposed on the first surface side of the plurality of sintered compacts and a target containing the R disposed on the second surface side of the plurality of sintered compacts, the film is simultaneously formed on the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig in an inert gas atmosphere. 2 In the grain boundary diffusion process, in a dual-sided film-forming processing chamber provided with a target containing the R disposed on the first surface side of the plurality of sintered compacts and a target containing the R disposed on the second surface side of the plurality of sintered compacts, the film is simultaneously formed on the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig in an inert gas atmosphere. the fixture is made of one or more materials selected from aluminum, aluminum alloy, copper, copper alloy, iron, iron alloy, titanium, titanium alloy, niobium, niobium alloy, tungsten, tungsten alloy, molybdenum and molybdenum alloy, the fixture is configured to hold the sintered compact in a holding portion with a sharpened front end, the moving distance of the front end of the holding portion within the elastic limit is more than twice the dimensional tolerance range of the dimension of the sintered compact in the clamping direction.

4. The method for preparing a rare earth magnet according to claim 3, It is characterized in that the double-sided film-forming treatment chamber is formed by arranging a plurality of film-forming treatment chambers in series, and the plurality of sintered compacts are continuously film-formed in an inert gas atmosphere without being exposed to the atmosphere.

5. The method for preparing a rare earth magnet according to any one of claims 1 to 4, It is characterized in that the portion of the holding portion other than the contact point with the sintered compact and the electrical connection point for grounding is coated with one or more materials selected from organic substances and ceramics.

6. The method for preparing a rare earth magnet according to any one of claims 1 to 4, It is characterized in that the grain boundary diffusion process includes one or more of the following processes: an atmosphere vacuum process of evacuating the atmosphere of the plurality of sintered compacts in a preparation chamber before putting the plurality of sintered compacts into the film-forming treatment chamber; an adsorbed gas dissociation process of dissociating adsorbed gas from the plurality of sintered compacts in a baking treatment chamber before putting the plurality of sintered compacts into the film-forming treatment chamber; a surface cleaning process of cleaning the surface of the plurality of sintered compacts in an anti-sputtering chamber before putting the plurality of sintered compacts into the film-forming treatment chamber; a heat treatment process of heat-treating the plurality of sintered compacts in a heat treatment chamber after forming the film on the surface of the plurality of sintered compacts; a cooling process of cooling the heat-treated plurality of sintered compacts in a cooling chamber; and an atmosphere opening process of making the atmosphere of the plurality of sintered compacts into atmospheric pressure in order to open the plurality of sintered compacts to the atmosphere in an extraction chamber. The film-forming treatment chamber is continuously connected to one or more chambers selected from the preparation chamber, the baking treatment chamber, the heat treatment chamber, the cooling chamber, and the take-out chamber.

7. The method for preparing a rare earth magnet according to any one of claims 1 to 4, wherein, The grain boundary diffusion process includes the following welding suppression process: after the film formation and before the heat treatment, by physical vapor growth method, one or more compounds selected from oxides, fluorides, and oxyfluorides of R 3 are formed on one or both of the first surface and the second surface of the plurality of sintered bodies arranged side by side using the jig; R 3 is one or more elements selected from rare earth elements, In the welding suppression step, in a welding suppression processing chamber provided with a target composed of one or more materials selected from the metal of R, the alloy of R, the oxide of R, the fluoride of R, and the oxyfluoride of R disposed on the first surface side of the plurality of sintered compacts, and a target composed of one or more materials selected from the metal of R, the alloy of R, the oxide of R, the fluoride of R, and the oxyfluoride of R disposed on the second surface side of the plurality of sintered compacts, the compound is formed into a film on one or both of the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig in a gas atmosphere of one or more gases selected from argon, oxygen, and nitrogen. 3 of R 3 of R 3 of R 3 of R 3 and a target composed of one or more materials selected from the metal of R, the alloy of R, the oxide of R, the fluoride of R, and the oxyfluoride of R disposed on the second surface side of the plurality of sintered compacts, 3 of R 3 of R 3 of R 3 of R 3 one or both of the first surface and the second surface of the plurality of sintered compacts arranged in parallel using the jig in a gas atmosphere of one or more gases selected from argon, oxygen, and nitrogen.

8. The method for preparing a rare earth magnet according to claim 7, wherein, The welding suppression step includes: a first welding suppression step of forming a film of the compound on the first surface of the plurality of sintered bodies arranged in parallel using the jig by physical vapor deposition in a first welding suppression treatment chamber provided with the target arranged on the first surface side of the plurality of sintered bodies; and a second welding suppression step of forming a film of the compound on the second surface of the plurality of sintered bodies arranged in parallel using the jig by physical vapor deposition in a second welding suppression treatment chamber provided with the target arranged on the second surface side of the plurality of sintered bodies.

9. The method for preparing a rare earth magnet according to claim 7, wherein, In the welding suppression step, in a double-sided welding suppression treatment chamber provided with the target arranged on the first surface side of the plurality of sintered bodies and the target arranged on the second surface side of the plurality of sintered bodies, a film of the compound is simultaneously formed on the first surface and the second surface of the plurality of sintered bodies arranged in parallel using the jig by physical vapor deposition.

10. The method for preparing a rare earth magnet according to any one of claims 1 to 4, wherein, The physical vapor deposition method is a sputtering method.

11. The method for preparing a rare earth magnet according to claim 7, wherein, The physical vapor deposition method in the welding suppression step is an RF sputtering method.

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