JP2020120102A - Method for manufacturing r-t-b based sintered magnet - Google Patents

Abstract

To provide a method for manufacturing an R-T-B based sintered magnet having high Hwhile decreasing a use amount of heavy rare earth RH.SOLUTION: A method for manufacturing an R-T-B based sintered magnet comprises the steps of: preparing a magnet material; preparing an RL-RH-M based alloy; and diffusion. In the diffusion step, an amount of deposition of the RL-RH-M based alloy to the R-T-B based sintered magnet material is 4 or more and 15 mass% or less, and an amount of RH deposition is 0.1 or more and 0.6 mass% or less. In the magnet material, the content of R is 27 or more and 35 mass% or less to a total amount of the magnet material, and the content of Fe to a total amount of T is 80 mass% or more. In the RL-RH-M based alloy, the content of RL is 60 or more and 97 mass% or less to a total amount of the RL-RH-M based alloy. The content of RH is 1 or more and 8 mass% or less to the total amount of the RL-RH-M based alloy, and the content of M is 2 or more and 39 mass% or less to the total amount of the RL-RH-M based alloy.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing an RTB-based sintered magnet.

The R-T-B system sintered magnet (R is at least one of rare earth elements, T is mainly Fe, and B is boron) is known as the most high-performance magnet among permanent magnets. It is used in various motors such as voice coil motors (VCM) for hard disk drives, motors for electric vehicles (EV, HV, PHV, etc.), motors for industrial equipment, and home electric appliances.

The RTB sintered magnet is mainly composed of a main phase mainly composed of an R ₂ T ₁₄ B compound and a grain boundary phase located at a grain boundary portion of the main phase. The R ₂ T ₁₄ B compound, which is the main phase, is a ferromagnetic material having a high saturation magnetization and an anisotropic magnetic field, and forms the basis of the characteristics of the RTB sintered magnet.

The _RTB sintered magnet has a problem that irreversible thermal demagnetization occurs because the coercive force _HcJ (hereinafter, simply referred to as " _HcJ ") decreases at high temperature. Therefore, in a particularly R-T-B based sintered magnet used in an electric vehicle motor, having a high H _cJ even at high temperatures, that is, required to have a higher H _cJ at room temperature.

International Publication No. 2007/102391 International Publication No. 2016/133071

It is known that when the light rare earth element (mainly Nd, Pr) in the R ₂ T ₁₄ B type compound phase is replaced with a heavy rare earth element (mainly Dy, Tb), H _cJ is improved. However, there is a problem that the residual magnetic flux density B _r (hereinafter, simply referred to as “B _r ”) is reduced because the saturation magnetization of the R ₂ T ₁₄ B type compound phase is reduced while the H _cJ is improved.

Patent Document 1 describes that a heavy rare earth element such as Dy is supplied to the surface of a sintered magnet of an RTB-based alloy and the heavy rare earth element is diffused inside the sintered magnet. In the method described in Patent Document 1, Dy is diffused from the surface of the RTB-based sintered magnet to the inside to concentrate Dy only in the outer shell portion of the main phase crystal grains effective for improving _HcJ . it makes while suppressing a decrease in _{B r,} it is possible to obtain a high _{H cJ.}

In Patent Document 2, an R-Ga-Cu alloy having a specific composition is brought into contact with the surface of the R-T-B system sintered body to perform heat treatment, whereby grain boundaries in the R-T-B system sintered magnet are obtained. Controlling the phase composition and thickness to improve H _cJ is described.

However, while reducing the amount of heavy rare earth elements in recent years, especially in an electric vehicle motors, it is required to obtain a higher B _r and a high H _cJ.

Various embodiments of the present disclosure, while reducing the amount of heavy rare earth elements, to provide a method of manufacturing a R-T-B based sintered magnet having a high B _r and high H _cJ.

In an exemplary embodiment, a method for manufacturing an RTB-based sintered magnet according to the present disclosure prepares an RTB-based sintered magnet material and an RL-RH-M-based alloy. Step, and at least a part of the RL-RH-M alloy is adhered to at least a part of the surface of the R-T-B system sintered magnet material, and 700°C or more 1100 in a vacuum or an inert gas atmosphere. A diffusion step of heating at a temperature of ℃ or less, the adhesion amount of the RL-RH-M alloy to the RTB-based sintered magnet material in the diffusion step is 4 mass% or more and 15 mass% or less. The amount of RH deposited on the RTB-based sintered magnet material by the RL-RH-M alloy is 0.1 mass% or more and 0.6 mass% or less, and the R-T-B system is In the sintered magnet material, R is a rare earth element and always contains at least one selected from the group consisting of Nd, Pr and Ce, and the content of R is the same as that of the entire RTB-based sintered magnet material. 27 mass% or more and 35 mass% or less, T is at least one selected from the group consisting of Fe, Co, Al, Mn, and Si, T always contains Fe, and the content of Fe with respect to the entire T is 80 mass. % Or more, and in the RL-RH-M alloy, RL is at least one of light rare earth elements, and at least contains at least one selected from the group consisting of Nd, Pr, and Ce. The content is 60 mass% or more and 97 mass% or less of the entire RL-RH-M alloy, RH is at least one selected from the group consisting of Tb, Dy and Ho, and the content of RH is RL. -RH-M system alloy whole 1 mass% or more and 8 mass% or less, M is at least one selected from the group consisting of Cu, Ga, Fe, Co, Ni, and Al, the content of M is , 2 mass% or more and 39 mass% or less of the entire RL-RH-M alloy.

In one embodiment, in the RL-RH-M-based alloy, the content of RH is 2 mass% or more and 6 mass% or less of the entire RL-RH-M-based alloy.

In one embodiment, the adhesion amount of the RL-RH-M alloy to the RTB-based sintered magnet material in the diffusion step is 5 mass% or more and 10 mass% or less.

According to embodiments of the present disclosure, while reducing the amount of heavy rare earth elements, it is possible to provide a manufacturing method of the R-T-B based sintered magnet having a high B _r and high H _cJ.

It is sectional drawing which expands a part of RTB type|system|group sintered magnet and shows it as a model. It is sectional drawing which expands the inside of the broken-line rectangular area of FIG. 1A, and is shown typically. 3 is a flowchart showing an example of steps in a method for manufacturing an RTB-based sintered magnet according to the present disclosure.

First, the basic structure of the RTB based sintered magnet according to the present disclosure will be described. R-T-B based sintered magnet, the powder particles of the raw material alloy has a structure bonded by sintering, and a main phase mainly composed of R _{2 T} 14 _B compound grains, the grain boundary portion of the main phase And a grain boundary phase located at.

FIG. 1A is a cross-sectional view schematically showing a part of the R-T-B system sintered magnet in an enlarged manner, and FIG. 1B is a cross-sectional view schematically showing an enlarged view in a broken-line rectangular region in FIG. 1A. Is. In FIG. 1A, for example, an arrow having a length of 5 μm is shown as a reference length indicating a size for reference. As shown in FIGS. 1A and 1B, the RTB-based sintered magnet includes a main phase 12 mainly composed of an R ₂ T ₁₄ B compound and a grain boundary phase 14 located at a grain boundary portion of the main phase 12. It consists of and. In addition, as shown in FIG. 1B, the grain boundary phase 14 includes a two-grain grain boundary phase 14 a in which two R ₂ T ₁₄ B compound particles (grains) are adjacent to each other and three R ₂ T ₁₄ B compound grains in adjacent to each other. Grain boundary triple point 14b. A typical main phase crystal grain size is 3 μm or more and 10 μm or less in average value of the circle equivalent diameter of the magnet cross section. The R ₂ T ₁₄ B compound that is the main phase 12 is a ferromagnetic material having high saturation magnetization and an anisotropic magnetic field. Therefore, in the R-T-B based sintered magnet, it is possible to improve the _{B r} by increasing the existence ratio of _R 2 _{T 14} B compound is the main phase 12. In order to increase the abundance ratio of the R ₂ T ₁₄ B compound, the R content, the T content, and the B content in the raw material alloy are set to the stoichiometric ratio of the R ₂ T ₁₄ B compound (R content:T content:B content= 2:14:1).

Further, by substituting a part of R of the main phase R ₂ T ₁₄ B compound with a heavy rare earth element such as Dy, Tb or Ho, it is possible to increase the anisotropic magnetic field of the main phase while lowering the saturation magnetization. It has been known. In particular, since the main phase shell that is in contact with the two-grain grain boundary phase is likely to become the starting point of the magnetization reversal, the heavy rare earth diffusion technology that can replace the main phase shell with the heavy rare earth element preferentially suppresses the decrease of the saturation magnetization and is efficient. High H _cJ is obtained.

On the other hand, it is known that high H _cJ can also be obtained by controlling the magnetism of the two-particle grain boundary phase 14a. Specifically, by lowering the concentration of magnetic elements (Fe, Co, Ni, etc.) in the two-grain grain boundary phase, the two-grain grain boundary phase becomes closer to non-magnetic, and magnetic coupling between the main phases is achieved. It can be weakened to suppress magnetization reversal.

In the method for manufacturing an RTB-based sintered magnet according to the present disclosure, the RB contained in the RL-RH-M alloy together with the RH contained in the RL-RH-M alloy from the surface of the RTB-based sintered magnet material to the inside of the magnet material through the grain boundaries. , RL and M are diffused. As a result of the study by the present inventor, the content of RH in the RL-RH-M alloy was lowered and the amount of adhesion to the surface of the RTB-based sintered magnet material was controlled to a relatively large specific range. When RH, RL, and M are diffused all together, the anisotropic magnetic field of the outer shell of the main phase is remarkably improved by diffusion even with a small amount of RH, and further, RL and M elements are diffused into the two-grain grain boundary phase. It was found that the concentration of magnetic elements in the grain boundary phase of two particles remarkably decreased. As a result, while suppressing the decrease in _{B r,} it is possible to obtain a high _{H cJ.} That is, according to the present disclosure, RH having a content within a specific range (1 mass% or more and 8 mass% or less) is combined with RL and M in a specific range (the surface of the RTB-based sintered magnet material of the RH-RL-M alloy). The adhesion amount is 4 mass% or more and 15 mass% or less, and the RH adhesion amount of the RL-RH-M alloy to the RTB-based sintered magnet material is 0.1 mass% or more and 0.6 mass% or less. ) when the diffused deposited allowed by the internal magnet material, in which a high B _r and high H _cJ was found that the resulting.

As shown in FIG. 2, the method for manufacturing an RTB-based sintered magnet according to the present disclosure includes a step S10 of preparing an RTB-based sintered magnet material and an RL-RH-M alloy. And step S20. The order of the step S10 of preparing the RTB-based sintered magnet material and the step S20 of preparing the RL-RH-M alloy is arbitrary, and the RTB-based firing manufactured at different locations respectively. Binder magnet material and RL-RH-M alloy may be used.

As shown in FIG. 2, the method for producing an RTB-based sintered magnet according to the present disclosure further includes an RL-RH-M-based alloy on at least a part of the surface of the RTB-based sintered magnet material. It includes a diffusion step S30 in which at least a part of the material is attached and heated at a temperature of 700° C. or higher and 1100° C. or lower in a vacuum or an inert gas atmosphere. The amount of the RL-RH-M alloy deposited on the R-T-B sintered magnet material in the diffusion step S30 is 4 mass% or more and 15 mass% or less.

In the present disclosure, the RTB-based sintered magnet before and during the diffusion step is referred to as an “RTB-based sintered magnet material”, and the RTB-based sintered magnet after the diffusion step is referred to. The binder magnet is simply referred to as "RTB-based sintered magnet".

(Process of preparing an RTB-based sintered magnet material)
In the R-T-B system sintered magnet material, R is a rare earth element and always contains at least one selected from the group consisting of Nd, Pr and Ce, and the content of R is the R-T-B system. It is not less than 27 mass% and not more than 35 mass% of the whole sintered magnet material. T is at least one selected from the group consisting of Fe, Co, Al, Mn, and Si, T always contains Fe, and the content of Fe in the whole T is 80 mass% or more.

When R is less than 27 mass %, a liquid phase is not sufficiently generated in the sintering process, and it may be difficult to sufficiently densify the sintered body. On the other hand, if R exceeds 35 mass%, grain growth may occur during sintering and H _cJ may decrease. R is preferably 28 mass% or more and 33 mass% or less.

The RTB-based sintered magnet material has, for example, the following composition range.
R: 27-35 mass%,
B: 0.80 to 1.20 mass%,
Ga: 0 to 1.0 mass%,
X: 0 to 2 mass% (X is at least one of Cu, Nb, and Zr),
T: Contains 60 mass% or more.

Preferably, in the RTB-based sintered magnet material, the molar ratio of [T]/[B] is more than 14.0 and 15.0 or less. Higher H _cJ can be obtained. [T]/[B] in the present disclosure is at least one element selected from the group consisting of each element (Fe, Co, Al, Mn, and Si) constituting T, and T always contains Fe, and T The analytical value (mass%) of Fe content with respect to the whole of 80 mass% or more was divided by the atomic weight of each element, and the sum of these values (a) and the analytical value of B (mass) were obtained. %) is the ratio (a/b) to that obtained by dividing the atomic weight of B by (b). The condition that the molar ratio [T]/[B] exceeds 14.0 indicates that the amount of B is relatively small with respect to the amount of T used for forming the main phase (R ₂ T ₁₄ B compound). There is. The molar ratio of [T]/[B] is more preferably 14.3 or more and 15.0 or less. Higher H _cJ can be obtained. The content of B is preferably 0.9 mass% or more and less than 1.0 mass% of the entire RTB-based sintered body.

The R-T-B system sintered magnet material can be prepared by using a general method for manufacturing a R-T-B system sintered magnet represented by an Nd-Fe-B system sintered magnet. As an example, a raw material alloy produced by a strip casting method or the like is crushed to a size of 3 μm or more and 10 μm or less by using a jet mill or the like, then molded in a magnetic field and sintered at a temperature of 900° C. or more and 1100° C. or less It can be prepared.

(Step of preparing RL-RH-M alloy)
In the RL-RH-M based alloy, RL is at least one of light rare earth elements, and at least contains at least one selected from the group consisting of Nd, Pr and Ce, and the content of RL is RL. -RH-M system alloy whole 60 mass% or more and 97 mass% or less. Examples of the light rare earth element include La, Ce, Pr, Nd, Pm, Sm and Eu. RH is at least one selected from the group consisting of Tb, Dy and Ho, and the content of RH is 1 mass% or more and 8 mass% or less of the entire RL-RH-M alloy. M is at least one selected from the group consisting of Cu, Ga, Fe, Co, Ni, and Al, and the content of M is 2 mass% or more and 39 mass% or less of the entire RL-RH-M alloy. is there. Typical examples of the RL-RH-M alloy are TbNdPrCu alloy, TbNdCePrCu alloy, TbNdGa alloy, TbNdPrGaCu alloy and the like. Further, RH fluorides, oxides, oxyfluorides and the like may be prepared together with the RL-M alloy. Examples of RH fluorides, oxides, and acid fluorides include TbF ₃ , DyF ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Tb ₄ OF, and Dy ₄ OF. The RL-RH-M based alloy contains a small amount of elements (for example, about 2 mass% in total) other than the above-mentioned elements by adjusting the contents of RL, RH, and M, respectively. Good.

If RL is less than 60 mass%, it becomes difficult for RH and M to be introduced into the R-T-B based sintered magnet material, and H _cJ may decrease, and if it exceeds 97 mass%, RL-RH-M. The alloy powder becomes very active during the manufacturing process of the base alloy. As a result, there is a possibility that remarkable oxidation or ignition of the alloy powder may occur. Preferably, the content of RL is 70 mass% or more and 95 mass% or less of the entire RL-RH-M alloy. Higher H _cJ can be obtained.

If the RH is less than 1 mass %, the H _cJ improving effect by RH may not be obtained, and if it exceeds 8 mass %, the H _cJ improving effect by RL and M may be reduced, so that the heavy rare earth element while reducing the amount of use, it may be impossible to obtain a R-T-B based sintered magnet having a high B _r and high H _cJ. Preferably, the content of RH is 2 mass% or more and 6 mass% or less of the entire RL-RH-M alloy. It is possible to obtain a higher _{B r} and a high _{H cJ.}

If M is less than 2 mass%, RL and RH are less likely to be introduced into the two-grain grain boundary phase, and H _cJ may not be sufficiently improved, and if it exceeds 39 mass%, the content of RL and RH is lowered and H _cJ may not be sufficiently improved. Preferably, the content of M is 3 mass% or more and 28 mass% or less of the entire RL-RH-M alloy. Higher H _cJ can be obtained. Further, M preferably contains Ga, and more preferably contains Cu. Higher H _cJ can be obtained.

The method for producing the RL-RH-M alloy is not particularly limited. It may be manufactured by a roll quenching method or a casting method. Further, these alloys may be crushed to form alloy powder. It may be produced by a known atomizing method such as a centrifugal atomizing method, a rotating electrode method, a gas atomizing method, or a plasma atomizing method.

(Diffusion process)
At least a part of the RL-RH-M alloy prepared as described above is attached to at least a part of the surface of the RTB-based sintered magnet material prepared as described above, and the temperature is set to 700 in a vacuum or an inert gas atmosphere. A diffusion process of heating at a temperature of not less than 1°C and not more than 1100°C is performed. As a result, a liquid phase containing RL, RH, and M is generated from the RL-RH-M alloy, and the liquid phase passes from the sintered material surface via the grain boundary in the RTB-based sintered magnet material. It is introduced by diffusion inside. The amount of the RL-RH-M alloy deposited on the R-T-B sintered magnet material in the diffusion step is 4 mass% or more and 15 mass% or less, and the R- by the RL-RH-M alloy is The amount of RH adhering to the TB type sintered magnet material is set to 0.1 mass% or more and 0.6 mass% or less. This makes it possible to obtain an extremely high H _cJ improving effect. If the amount of the RL-RH-M based alloy deposited on the R-T-B based sintered magnet material is less than 4 mass%, the amount of RH, RL and M introduced into the magnet material is too small and the H _cJ is high _. may not be obtained, exceeds 15 mass%, or B _r is significantly lower too much introduction amount of RH and RL and M, only the amount of the heavy rare earth element is too increased Not only that, the RL-RH-M-based alloy that cannot be completely diffused into the magnet may remain on the surface of the magnet, causing another problem such as corrosion resistance and workability. Preferably, the amount of the RL-RH-M alloy deposited on the R-T-B sintered magnet material is 5 mass% or more and 10 mass% or less. Higher H _cJ can be obtained. Further, if the amount of RH adhered to the RTB-based sintered magnet material by the RL-RH-M alloy is less than 0.1 mass%, the effect of improving _HcJ by RH may not be obtained. However, if it exceeds 0.6 mass %, it is impossible to obtain an _RTB -based sintered magnet having a high H _cJ while reducing the amount of heavy rare earth elements used. Preferably, the amount of RH deposited on the R-T-B based sintered magnet material by the RL-RH-M based alloy is 0.1 mass% or more and 0.5 mass% or less.

Here, the adhered amount of RH is the amount of RH contained in the RL-RH-M system alloy adhered to the R-T-B system sintered magnet material, and the R-T-B system sintered magnet material. Is defined by the mass ratio when the mass of 100 mass% is set.

When the heating temperature in the diffusion step is lower than 700° C., the amount of liquid phase containing RH, RL and M may be too small to obtain high H _cJ . On the other hand, if it exceeds 1100° C., H _cJ may be significantly reduced. Preferably, the heating temperature in the diffusion step is 800° C. or higher and 1000° C. or lower. Higher H _cJ can be obtained. In addition, preferably, for the RTB-based sintered magnet that has been subjected to the diffusion step (700° C. or more and 1100° C. or less), from the temperature at which the diffusion step is performed to 300° C. at a cooling rate of 15° C./min or more. It is preferable to cool. Higher H _cJ can be obtained.

The diffusion step can be performed using a known heat treatment device by placing an RL-RH-M alloy having an arbitrary shape on the surface of the RTB-based sintered magnet material. For example, the surface of the R-T-B based sintered magnet material may be covered with a powder layer of the RL-RH-M alloy to perform the diffusion step. For example, you may perform the application process of apply|coating a pressure sensitive adhesive on the surface of a coating object, and the process of making a RL-RH-M alloy adhere to the area|region where the pressure sensitive adhesive was applied. Examples of the adhesive include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), PVP (polyvinylpyrrolidone), and the like. When the pressure-sensitive adhesive is a water-based pressure-sensitive adhesive, the RTB-based sintered magnet material may be preliminarily heated before coating. The purpose of preheating is to remove excess solvent to control the adhesive strength, and to adhere the adhesive evenly. The heating temperature is preferably 60 to 200°C. This step may be omitted in the case of a highly volatile organic solvent-based pressure-sensitive adhesive. In addition, for example, a slurry in which an RL-RH-M alloy is dispersed in a dispersion medium is applied to the surface of an RTB-based sintered magnet material, and then the dispersion medium is evaporated to evaporate the RL-RH-M alloy and R-T. A B-based sintered magnet material may be attached. Examples of the dispersion medium include alcohol (such as ethanol), aldehyde and ketone. Further, RH may be introduced by arranging a fluoride, oxide, oxyfluoride or the like of RH together with the RL-M alloy on the surface of the RTB-based sintered magnet material. That is, the method is not particularly limited as long as RL and M can be diffused simultaneously with RH.

Further, if at least a part of the RL-RH-M alloy is attached to at least a part of the RTB-based sintered magnet material, the arrangement position thereof is not particularly limited, but preferably RL-RH- The M alloy is arranged so as to adhere to at least the surface perpendicular to the orientation direction of the RTB sintered magnet material. The liquid phase containing RL, RH, and M can be more efficiently diffused and introduced from the magnet surface to the inside. In this case, even if the RL-RH-M alloy is adhered only in the orientation direction of the RTB-based sintered magnet material, the RL-RH-M alloy is applied to the entire surface of the RTB-based sintered magnet material. It may be attached.

(Process of performing heat treatment)
Preferably, with respect to the RTB-based sintered magnet that has been subjected to the diffusion step, the temperature is 400° C. or higher and 750° C. or lower in a vacuum or an inert gas atmosphere, and is lower than the temperature performed in the diffusion step. Heat treatment is performed at a temperature. Higher H _cJ can be obtained by performing the heat treatment.

The present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Experimental example 1
[Step of preparing RTB sintered magnet material (magnet material)]
Each element was weighed and cast by a strip casting method so as to have the composition of the magnet raw material shown by reference numeral 1-A in Table 1, and a flaky raw material alloy having a thickness of 0.2 to 0.4 mm was obtained. The obtained flaky raw material alloy was pulverized with hydrogen and then subjected to a dehydrogenation treatment of heating in vacuum to 550° C. and then cooling to obtain coarsely pulverized powder. Next, after adding zinc stearate as a lubricant to the obtained coarsely pulverized powder in an amount of 0.04 mass% with respect to 100 mass% of the coarsely pulverized powder and mixing them, nitrogen was obtained by using an air flow type pulverizer (jet mill device). Dry pulverization was performed in an air stream to obtain finely pulverized powder (alloy powder) having a particle size D ₅₀ of 4 μm. The particle size D ₅₀ is a volume center value (volume-based median diameter) obtained by a laser diffraction method using an air flow dispersion method.

Zinc stearate as a lubricant was added to the finely pulverized powder in an amount of 0.05 mass% with respect to 100 mass% of the finely pulverized powder, and the mixture was molded in a magnetic field to obtain a molded body. A so-called orthogonal magnetic field molding device (transverse magnetic field molding device) in which the magnetic field applying direction and the pressurizing direction are orthogonal to each other was used as the molding device.

The obtained molded body was sintered in a vacuum for 4 hours (selecting a temperature at which sufficient densification by sintering occurs) and then rapidly cooled to obtain a magnet material. The density of the obtained magnet material was 7.5 Mg/m ³ or more. Table 1 shows the results of the components of the obtained magnet material. In addition, each component in Table 1 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). In addition, as a result of measuring the oxygen content of the magnet material by the gas melting-infrared absorption method, it was confirmed that all were about 0.1 mass %. Moreover, as a result of measuring C (carbon content) using a gas analyzer by a combustion-infrared absorption method, it was confirmed that it was around 0.1 mass %. “[T]/[B]” in Table 1 is obtained by dividing the analytical value (mass %) for each element (Fe, Co, Al, Si, Mn) constituting T by the atomic weight of the element. It is the ratio (a/b) of the value obtained by summing these values (a) and the value obtained by dividing the B analysis value (mass %) by the atomic weight of B (b). The same applies to all the tables below. In addition, even if each composition, oxygen content, and carbon content of Table 1 are added together, it does not become 100 mass %. This is because the analysis method differs depending on each component as described above. The same applies to the other tables.

[Process of preparing RL-RH-M alloy]
Each element is weighed and the raw materials thereof are melted so as to have the composition of the RL-RH-M-based alloy shown by reference numeral 1-a in Table 2, and ribbons or flakes are prepared by a single roll ultra-quenching method (melt spinning method). A shaped alloy was obtained. Table 2 shows the composition of the obtained RL-RH-M alloy. In addition, each component in Table 2 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES).

[Diffusion process]
The R-T-B based sintered magnet material of 1-A in Table 1 was cut and cut into a cube of 7.2 mm x 7.2 mm x 7.2 mm. PVA as an adhesive was applied to the entire surface of the RTB-based sintered magnet material by a dipping method on the processed RTB-based sintered magnet material. Next, the RL-RH-M type alloy was adhered to the entire surface of the R-T-B type sintered magnet material coated with the pressure-sensitive adhesive under the production conditions shown in Table 3. In addition, the RL-RH-M alloy deposition amount and the RH deposition amount are obtained by crushing the RL-RH-M alloy in an argon atmosphere using a mortar and then passing through several kinds of sieves having openings of 38 to 1000 μm. It was adjusted by using RL-RH-M type alloys having different grain sizes. Then, using a vacuum heat treatment furnace, the RL-RH-M alloy and the RTB sintered magnet material were heated under reduced pressure argon controlled to 200 Pa under the conditions shown in the diffusion step of Table 3. Then, it cooled.

[Step of performing heat treatment]
After the diffusion step, the RTB-based sintered magnet was subjected to a heat treatment of heating it to 500° C. in reduced pressure argon controlled to 200 Pa using a vacuum heat treatment furnace. The entire surface of each sample after the heat treatment was cut using a surface grinder to obtain a cubic sample (RTB sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. Obtained. The heating temperature of the RL-RH-M alloy and the RTB-based sintered magnet material in the step of performing the diffusion step, and the RTB-type in the step of performing heat treatment after the diffusion step. The heating temperature of the sintered magnet material was measured with a thermocouple.

[sample test]
The obtained sample was measured _{B r} and _{H cJ} of each sample by the B-H tracer. The measurement results are shown in Table 3. As shown in Table 3, sample No. The present invention Examples of 1-4～1-7 are all while reducing the amount of heavy rare earth elements, it can be seen that obtain a high B _r and high H _cJ. On the other hand, the sample No. in which the adhesion amount of the RL-RH-M alloy is less than 4 mass%. No high H _cJ was obtained for 1-1 to 1-3. Furthermore, the sample No. in which the adhesion amount of the RL-RH-M alloy is more than 15 mass%. In 1-9, Br is significantly reduced. In addition, the sample No. 1-8 is higher _{B r} and high _{H cJ} are obtained, a RH adhesion amount 0.6 mass% _greater, and _{H cJ} from _{H cJ} improvement is low (No. 1-7 is significantly improved No, and _Br has fallen). Therefore, while reducing the amount of heavy rare earth elements, it is impossible to obtain a R-T-B based sintered magnet having a high B _r and high H _cJ.

Experimental example 2
[Step of preparing RTB sintered magnet material (magnet material)]
Each element was weighed and cast by the strip casting method so as to have the composition of the magnet raw material shown by symbol 2-A in Table 4, and a flaky raw material alloy having a thickness of 0.2 to 0.4 mm was obtained. The obtained flaky raw material alloy was pulverized with hydrogen and then subjected to a dehydrogenation treatment of heating in vacuum to 550° C. and then cooling to obtain coarsely pulverized powder. Next, after adding zinc stearate as a lubricant to the obtained coarsely pulverized powder in an amount of 0.04 mass% with respect to 100 mass% of the coarsely pulverized powder and mixing them, nitrogen was obtained by using an air flow type pulverizer (jet mill device). Dry pulverization was performed in an air stream to obtain finely pulverized powder (alloy powder) having a particle size D ₅₀ of 4 μm. The particle size D ₅₀ is a volume center value (volume-based median diameter) obtained by a laser diffraction method using an air flow dispersion method.

Zinc stearate as a lubricant was added to the finely pulverized powder in an amount of 0.05 mass% with respect to 100 mass% of the finely pulverized powder, and the mixture was molded in a magnetic field to obtain a molded body. A so-called orthogonal magnetic field molding device (transverse magnetic field molding device) in which the magnetic field applying direction and the pressurizing direction are orthogonal to each other was used as the molding device.

The obtained molded body was sintered in a vacuum for 4 hours (selecting a temperature at which sufficient densification by sintering occurs) and then rapidly cooled to obtain a magnet material. The density of the obtained magnet material was 7.5 Mg/m ³ or more. Table 1 shows the results of the components of the obtained magnet material. In addition, each component in Table 4 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). In addition, as a result of measuring the oxygen content of the magnet material by the gas melting-infrared absorption method, it was confirmed that all were about 0.1 mass %. Moreover, as a result of measuring C (carbon content) using a gas analyzer by a combustion-infrared absorption method, it was confirmed that it was around 0.1 mass %.

[Process of preparing RL-RH-M alloy]
Each element is weighed and the raw materials thereof are melted so as to have the composition of the RL-RH-M alloy shown by the symbols 2-a to 2-g in Table 5, and the single roll ultra-quenching method (melt spinning method) is used. A ribbon or flake alloy was obtained by. Table 5 shows the composition of the obtained RL-RH-M alloy. In addition, each component in Table 5 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES).

[Diffusion process]
The R-T-B based sintered magnet material with the code 2-A in Table 4 was cut and cut into a cube of 7.2 mm x 7.2 mm x 7.2 mm. PVA as an adhesive was applied to the entire surface of the RTB-based sintered magnet material by a dipping method on the processed RTB-based sintered magnet material. Next, the RL-RH-M type alloy was adhered to the entire surface of the R-T-B type sintered magnet material coated with the pressure-sensitive adhesive under the production conditions shown in Table 6. In addition, the RL-RH-M alloy deposition amount and the RH deposition amount are obtained by crushing the RL-RH-M alloy in an argon atmosphere using a mortar and then passing through several kinds of sieves having openings of 38 to 1000 μm. It was adjusted by using RL-RH-M type alloys having different grain sizes. Then, using a vacuum heat treatment furnace, the RL-RH-M alloy and the RTB sintered magnet material were heated under reduced pressure argon controlled to 200 Pa under the conditions shown in the diffusion step of Table 6. Then, it cooled.

[Step of performing heat treatment]
After the diffusion step, the RTB-based sintered magnet was subjected to a heat treatment of heating it to 500° C. in reduced pressure argon controlled to 200 Pa using a vacuum heat treatment furnace. The entire surface of each sample after the heat treatment was cut using a surface grinder to obtain a cubic sample (RTB sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. Obtained. The heating temperature of the RL-RH-M alloy and the RTB-based sintered magnet material in the step of performing the diffusion step, and the RTB-type in the step of performing heat treatment after the diffusion step. The heating temperature of the sintered magnet material was measured with a thermocouple.

[sample test]
The obtained sample was measured _{B r} and _{H cJ} of each sample by the B-H tracer. The measurement results are shown in Table 6. As shown in Table 6, sample No. The present invention Examples of 2-2～2-7 are all while reducing the amount of heavy rare earth elements, it can be seen that obtain a high B _r and high H _cJ. On the other hand, Sample No. in which the RH amount of the RL-RH-M alloy is less than 1%. No high H _cJ was obtained for 2-1. In addition, the sample No. 2-8 is higher _{B r} and high _{H cJ} are obtained, the amount RH of RL-RH-M alloy is 8 percent, and RH adhesion amount is 0.6 mass _{percent, H cJ} increased The effect is low (from _No. 2-7, H _cJ is hardly improved). Therefore, while reducing the amount of heavy rare earth elements, it is impossible to obtain a R-T-B based sintered magnet having a high B _r and high H _cJ.

Experimental example 3
[Step of preparing RTB sintered magnet material (magnet material)]
Each element was weighed and cast by the strip casting method so as to have the composition of the magnet material shown by the reference numeral 3-A in Table 7, and a flaky raw material alloy having a thickness of 0.2 to 0.4 mm was obtained. The obtained flaky raw material alloy was pulverized with hydrogen and then subjected to a dehydrogenation treatment of heating in vacuum to 550° C. and then cooling to obtain coarsely pulverized powder. Next, after adding zinc stearate as a lubricant to the obtained coarsely pulverized powder in an amount of 0.04 mass% with respect to 100 mass% of the coarsely pulverized powder and mixing them, nitrogen was obtained by using an air flow type pulverizer (jet mill device). Dry pulverization was performed in an air stream to obtain finely pulverized powder (alloy powder) having a particle size D ₅₀ of 4 μm. The particle size D ₅₀ is a volume center value (volume-based median diameter) obtained by a laser diffraction method using an air flow dispersion method.

Zinc stearate as a lubricant was added to the finely pulverized powder in an amount of 0.05 mass% with respect to 100 mass% of the finely pulverized powder, and the mixture was molded in a magnetic field to obtain a molded body. A so-called orthogonal magnetic field molding device (transverse magnetic field molding device) in which the magnetic field applying direction and the pressurizing direction are orthogonal to each other was used as the molding device.

The obtained molded body was sintered in a vacuum for 4 hours (selecting a temperature at which sufficient densification by sintering occurs) and then rapidly cooled to obtain a magnet material. The density of the obtained magnet material was 7.5 Mg/m ³ or more. Table 7 shows the results of the components of the obtained magnetic material. In addition, each component in Table 7 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). In addition, as a result of measuring the oxygen content of the magnet material by the gas melting-infrared absorption method, it was confirmed that all were about 0.1 mass %. Moreover, as a result of measuring C (carbon content) using a gas analyzer by a combustion-infrared absorption method, it was confirmed that it was around 0.1 mass %.

[Process of preparing RL-RH-M alloy]
Each element is weighed and the raw materials thereof are melted so as to have the composition of the RL-RH-M alloy shown by symbol 3-a in Table 8, and ribbons or flakes are formed by a single roll ultra-quenching method (melt spinning method). A shaped alloy was obtained. The obtained alloy was pulverized in an argon atmosphere using a mortar, and then passed through a sieve having an opening of 300 μm to prepare an RL-RH-M alloy. Table 8 shows the composition of the obtained RL-RH-M alloy. In addition, each component in Table 8 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES).

[Diffusion process]
The R-T-B based sintered magnet material indicated by the reference numeral 3-A in Table 9 was cut and cut into a cube of 7.2 mm x 7.2 mm x 7.2 mm. PVA as an adhesive was applied to the entire surface of the RTB-based sintered magnet material by a dipping method on the processed RTB-based sintered magnet material. Next, the RL-RH-M type alloy was adhered to the entire surface of the R-T-B type sintered magnet material coated with the adhesive under the production conditions shown in Table 9. Then, using a vacuum heat treatment furnace, the RL-RH-M alloy and the RTB sintered magnet material were heated under reduced pressure argon controlled to 200 Pa under the conditions shown in the diffusion step of Table 9. Then, it cooled.

[Step of performing heat treatment]
After the diffusion step, the RTB-based sintered magnet was subjected to a heat treatment of heating it to 500° C. in reduced pressure argon controlled to 200 Pa using a vacuum heat treatment furnace. The entire surface of each sample after the heat treatment was cut using a surface grinder to obtain a cubic sample (RTB sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. Obtained. The heating temperature of the RL-RH-M alloy and the RTB-based sintered magnet material in the step of performing the diffusion step, and the RTB-type in the step of performing heat treatment after the diffusion step. The heating temperature of the sintered magnet material was measured with a thermocouple.

[sample test]
The obtained sample was measured _{B r} and _{H cJ} of each sample by the B-H tracer. The measurement results are shown in Table 9. As shown in Table 9, sample No. The present invention Examples of 3-2～3-8 are all while reducing the amount of heavy rare earth elements, it can be seen that obtain a high B _r and high H _cJ. On the other hand, the sample No. whose treatment temperature in the diffusion step is less than 700° C. 3-1 could not obtain high _HcJ . Further, in the sample No. 1 having a treatment temperature of more than 1100° C. in the diffusion step. 3-9 is reduced _{B r} and _{H cJ} significantly.

Experimental example 4
[Step of preparing RTB sintered magnet material (magnet material)]
Each element was weighed and cast by the strip casting method so as to have the composition of the magnet material shown by the symbols 4-A to 4-D in Table 10, and a flaky raw material alloy having a thickness of 0.2 to 0.4 mm was obtained. It was The obtained flaky raw material alloy was pulverized with hydrogen and then subjected to a dehydrogenation treatment of heating in vacuum to 550° C. and then cooling to obtain coarsely pulverized powder. Next, after adding zinc stearate as a lubricant to the obtained coarsely pulverized powder in an amount of 0.04 mass% with respect to 100 mass% of the coarsely pulverized powder and mixing them, nitrogen was obtained by using an air flow type pulverizer (jet mill device). Dry pulverization was performed in an air stream to obtain finely pulverized powder (alloy powder) having a particle size D ₅₀ of 4 μm. The particle size D ₅₀ is a volume center value (volume-based median diameter) obtained by a laser diffraction method using an air flow dispersion method.

Zinc stearate as a lubricant was added to the finely pulverized powder in an amount of 0.05 mass% with respect to 100 mass% of the finely pulverized powder, and the mixture was molded in a magnetic field to obtain a molded body. A so-called orthogonal magnetic field molding device (transverse magnetic field molding device) in which the magnetic field applying direction and the pressurizing direction are orthogonal to each other was used as the molding device.

The obtained molded body was sintered in vacuum at a temperature of 1000° C. or higher and 1050° C. or lower (a temperature at which sufficient densification by sintering is sufficiently selected is selected for each sample) for 4 hours and then rapidly cooled to obtain a magnet material. The density of the obtained magnet material was 7.5 Mg/m ³ or more. Table 1 shows the results of the components of the obtained magnet material. In addition, each component in Table 10 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). In addition, as a result of measuring the oxygen content of the magnet material by the gas melting-infrared absorption method, it was confirmed that all were about 0.1 mass %. Moreover, as a result of measuring C (carbon content) using a gas analyzer by a combustion-infrared absorption method, it was confirmed that it was around 0.1 mass %.

[Process of preparing RL-RH-M alloy]
Each element is weighed and the raw materials thereof are melted so as to have the composition of the RL-RH-M alloy shown by the symbol 4-a in Table 11, and ribbons or flakes are prepared by the single-roll ultra-quenching method (melt spinning method). A shaped alloy was obtained. The obtained alloy was crushed in an argon atmosphere using a mortar and then passed through a sieve with a mesh opening of 300 μm to prepare an RL-RH-M alloy. Table 11 shows the composition of the obtained RL-RH-M alloy. In addition, each component in Table 11 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES).

[Diffusion process]
The RTB-based sintered magnet materials indicated by the symbols 4-A to 4-D in Table 10 were cut and cut into a cube of 7.2 mm×7.2 mm×7.2 mm. PVA as an adhesive was applied to the entire surface of the RTB-based sintered magnet material by a dipping method on the processed RTB-based sintered magnet material. Next, the RL-RH-M alloy was adhered to the entire surface of the R-T-B sintered magnet material coated with the pressure-sensitive adhesive under the manufacturing conditions shown in Table 12. Then, using a vacuum heat treatment furnace, the RL-RH-M alloy and the RTB sintered magnet material were heated under reduced pressure argon controlled to 200 Pa under the conditions shown in the diffusion step of Table 12. Then, it cooled.

[Step of performing heat treatment]
After the diffusion step, the RTB-based sintered magnet was subjected to a heat treatment of heating it to 500° C. in reduced pressure argon controlled to 200 Pa using a vacuum heat treatment furnace. The entire surface of each sample after the heat treatment was cut using a surface grinder to obtain a cubic sample (RTB sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. Obtained. The heating temperature of the RL-RH-M alloy and the RTB-based sintered magnet material in the step of performing the diffusion step, and the RTB-type in the step of performing heat treatment after the diffusion step. The heating temperature of the sintered magnet material was measured with a thermocouple.

[sample test]
The obtained sample was measured _{B r} and _{H cJ} of each sample by the B-H tracer. The measurement results are shown in Table 12. As shown in Table 12, sample No. The present invention Examples of 4-1 to 4-4 are all while reducing the amount of heavy rare earth elements, it can be seen that obtain a high B _r and high H _cJ.

Example 5
[Step of preparing RTB sintered magnet material (magnet material)]
Each element was weighed and cast by the strip casting method so as to have the composition of the magnet material shown by the symbol 5-A in Table 13, and a flaky raw material alloy having a thickness of 0.2 to 0.4 mm was obtained. The obtained flaky raw material alloy was pulverized with hydrogen and then subjected to a dehydrogenation treatment of heating in vacuum to 550° C. and then cooling to obtain coarsely pulverized powder. Next, after adding zinc stearate as a lubricant to the obtained coarsely pulverized powder in an amount of 0.04 mass% with respect to 100 mass% of the coarsely pulverized powder and mixing them, nitrogen was obtained by using an air flow type pulverizer (jet mill device). Dry pulverization was performed in an air stream to obtain finely pulverized powder (alloy powder) having a particle size D ₅₀ of 4 μm. The particle size D ₅₀ is a volume center value (volume-based median diameter) obtained by a laser diffraction method using an air flow dispersion method.

Zinc stearate as a lubricant was added to the finely pulverized powder in an amount of 0.05 mass% with respect to 100 mass% of the finely pulverized powder, and the mixture was molded in a magnetic field to obtain a molded body. A so-called orthogonal magnetic field molding device (transverse magnetic field molding device) in which the magnetic field applying direction and the pressurizing direction are orthogonal to each other was used as the molding device.

The obtained molded body was sintered in vacuum at 1040° C. (a temperature at which sufficient densification by sintering is sufficiently selected) was sintered for 4 hours and then quenched to obtain a magnet material. The density of the obtained magnet material was 7.5 Mg/m ³ or more. Table 13 shows the results of the components of the obtained magnetic material. In addition, each component in Table 13 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). In addition, as a result of measuring the oxygen content of the magnet material by the gas melting-infrared absorption method, it was confirmed that all were about 0.1 mass %. Moreover, as a result of measuring C (carbon content) using a gas analyzer by a combustion-infrared absorption method, it was confirmed that it was around 0.1 mass %. “[T]/[B]” in Table 13 is obtained by dividing the analytical value (mass%) for each element (here, Fe, Al, Si, and Mn) constituting T by the atomic weight of the element. It is the ratio (a/b) of the value obtained by summing these values (a) and the value obtained by dividing the B analysis value (mass %) by the atomic weight of B (b). The same applies to all the tables below. In addition, even if each composition, oxygen content, and carbon content of Table 13 are added together, it does not reach 100 mass %. This is because the analysis method differs depending on each component as described above. The same applies to the other tables.

[Process of preparing RL-RH-M alloy]
Each element is weighed and the raw materials thereof are melted so that the composition of the RL-RH-M alloy shown by the symbols 5-a to 5-n in Table 14 is obtained, and the single roll ultra-quenching method (melt spinning method) is performed. A ribbon or flake alloy was obtained by. The obtained alloy was pulverized in an argon atmosphere using a mortar, and then passed through a sieve having an opening of 300 μm to prepare an RL-RH-M alloy. Table 14 shows the composition of the obtained RL-RH-M alloy. In addition, each component in Table 14 was measured using the high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES).

[Diffusion process]
The R-T-B based sintered magnet material of 5-A in Table 13 was cut and cut into a cube of 7.2 mm×7.2 mm×7.2 mm. Next, PVA as an adhesive was applied to the entire surface of the RTB sintered magnet material by an dipping method on the RTB sintered magnet material. The RL-RH-M alloy powder was adhered to the R-T-B sintered magnet material coated with the adhesive. The RL-RH-M alloy powder was spread in a processing container and attached to the entire surface of the R-T-B sintered magnet material coated with an adhesive. Next, using a vacuum heat treatment furnace, the RL-RH-M-based alloy and the RTB-based sintered magnet material are heated at a temperature shown in the diffusion step of Table 15 in reduced pressure argon controlled to 200 Pa. After carrying out the diffusion process, the sample was cooled.

[Step of performing heat treatment]
The heat treatment after the diffusion step is performed on the RTB-based sintered magnet material that has been subjected to the diffusion step at 500° C. in reduced pressure argon controlled to 200 Pa using a vacuum heat treatment furnace, and then cooled. did. The surface of each sample after the heat treatment was cut using a surface grinder to obtain a cubic sample (RTB sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. Obtained. The heating temperature of the RL-RH-M alloy and the RTB-based sintered magnet material in the step of performing the diffusion step, and the RTB-type in the step of performing heat treatment after the diffusion step. The heating temperature of the sintered magnet material was measured by attaching a thermocouple to each.

[sample test]
Br and HcJ of each sample of the obtained sample were measured by a BH tracer. The measurement results are shown in Table 15. Table 15 shows the results of measuring the components of the sample by using high frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). As shown in Table 15, sample No. It can be seen that in all the invention examples 5-1 to 5-14, high Br and high HcJ were obtained.

According to the present disclosure, an RTB-based sintered magnet having a high residual magnetic flux density and a high coercive force can be manufactured. INDUSTRIAL APPLICABILITY The sintered magnet according to the present disclosure is suitable for various motors such as a motor mounted on a hybrid vehicle exposed to high temperatures, home electric appliances, and the like.

12... Main phase composed of R ₂ T ₁₄ B compound, 14... Grain boundary phase, 14a... Two-grain grain boundary phase, 14b... Grain boundary triple point

Claims (3)

A step of preparing an RTB-based sintered magnet material,
A step of preparing an RL-RH-M alloy,
At least a portion of the RL-RH-M alloy is attached to at least a portion of the surface of the RTB-based sintered magnet material, and the temperature is 700°C or more and 1100°C or less in a vacuum or an inert gas atmosphere. A diffusion step of heating at temperature,
Including
The amount of the RL-RH-M based alloy deposited on the R-T-B based sintered magnet material in the diffusion step is 4 mass% or more and 15 mass% or less, and the R based on the RL-RH-M based alloy. The amount of RH adhering to the -TB sintered magnet material is 0.1 mass% or more and 0.6 mass% or less,
In the R-T-B system sintered magnet material,
R is a rare earth element and always contains at least one selected from the group consisting of Nd, Pr and Ce, and the content of R is 27 mass% or more and 35 mass% or less of the entire RTB-based sintered magnet material. And
T is at least one selected from the group consisting of Fe, Co, Al, Mn, and Si, T always contains Fe, and the content of Fe with respect to the entire T is 80 mass% or more,
In the RL-RH-M type alloy,
RL is at least one of the light rare earth elements and always contains at least one selected from the group consisting of Nd, Pr and Ce, and the content of RL is 60 mass% of the entire RL-RH-M alloy. Is 97 mass% or less,
RH is at least one selected from the group consisting of Tb, Dy and Ho, and the content of RH is 1 mass% or more and 8 mass% or less of the entire RL-RH-M alloy,
M is at least one selected from the group consisting of Cu, Ga, Fe, Co, Ni, and Al, and the content of M is 2 mass% or more and 39 mass% or less of the entire RL-RH-M alloy. is there,
A method for manufacturing an RTB-based sintered magnet. In the RL-RH-M system alloy, the content of RH is 2 mass% or more and 6 mass% or less of the entire RL-RH-M system alloy, of the RTB sintered magnet according to claim 1. Production method. The R-T- according to claim 1 or 2, wherein the amount of the RL-RH-M alloy deposited on the R-T-B sintered magnet material in the diffusion step is 5 mass% or more and 10 mass% or less. A method for manufacturing a B-based sintered magnet.

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