JP2021153146A - 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 which has high HcJ while reducing an amount of using heavy rare earth RH.SOLUTION: A method for manufacturing an R-T-B based sintered magnet comprises: a step of making a sintered compact of fine powder having particle size D50 of 2.0-3.5 μm to prepare an R-T-B based sintered magnet material; a step of preparing an RL-RH-M based alloy; and a diffusion step of depositing at least part of the RL-RH-M based alloy to at least part of the surface of the R-T-B based sintered magnet material, and heating them at a temperature of 700°C up to 1100°C in a vacuum or inert gas atmosphere. In the diffusion step, an amount of the RL-RH-M based alloy depositing to the R-T-B based sintered magnet material is 1 mass% or more and 2.5 mass% or less.SELECTED DRAWING: Figure 2

Description

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

RT-B-based sintered magnets (R is at least one of the rare earth elements, T is mainly Fe, and B is boron) are known as the highest performance magnets 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 appliances.

R-T-B based sintered magnet is mainly composed of a main phase consisting of R _{2 T} 14 _B compound, and the grain boundary phase located in the grain boundary of the main phase. The main phase, R ₂ T ₁₄ B compound, is a ferromagnetic material with high saturation magnetization and anisotropic magnetic field, and forms the basis of the characteristics of R-TB based sintered magnets.

_{The RTB} -based sintered magnet has a problem that irreversible thermal demagnetization occurs because the coercive force H cJ (hereinafter, simply referred to as “H _{cJ”) decreases at a 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.

It is known that _{H cJ} is improved by substituting light rare earth elements (mainly Nd, Pr) in the R ₂ T ₁₄ B type compound phase with heavy rare earth elements (mainly Dy, Tb). However, while the H _cJ is improved, the residual magnetic flux density B _{r (hereinafter,} simply referred to as "B _r") in the saturation magnetization of the R 2 _T 14 _B compound phase is lowered is lowered.

Patent Document 1 describes that while supplying a heavy rare earth element such as Dy to the surface of a sintered magnet of an RTB alloy, the heavy rare earth element RH is diffused inside the sintered magnet. .. The method described in Patent Document 1 diffuses Dy 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 which is effective for improving _HcJ. it allows to reduce the amount of RH, while further suppressing a decrease in B _r, it is possible to obtain a high H _cJ.

According to Patent Document 2, grain boundaries in an RTB-based sintered magnet are obtained by contacting the surface of an R-TB-based sintered body with an R-Ga-Cu alloy having a specific composition and performing heat treatment. It has been described that the composition and thickness of the phase are controlled to _{improve HcJ.}

International Publication No. 2007/10231 International Publication No. 2016/133071

However, while reducing the amount of expensive heavy rare earth elements such as in recent particular motor for an electric vehicle, it has been 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 the method for producing an RTB-based sintered magnet of the present disclosure, in an exemplary embodiment, a _{sintered body is produced from a fine powder having a particle size D 50} of 2.0 μm to 3.5 μm to prepare an RT. -B-based 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 T is from the group consisting of Fe, Co, Al, Mn, and Si. The step of preparing at least one selected, where T always contains Fe) and the RL-RH-M based alloy (RL is at least one of the light rare earth elements, Nd, Pr and Ce. It always comprises at least one selected from the group consisting of, RH is at least one selected from the group consisting of Tb, Dy and Ho, and M is Cu, Ga, Fe, Co, Ni, and Al. At least a part of the RL-RH-M alloy on at least a part of the surface of the RTB-based sintered magnet material. In the RTB-based sintered magnet material, the content of R is R. -The total content of the TB-based sintered magnet material is 27 mass% or more and 35 mass% or less, the Fe content with respect to the entire T is 80 mass% or more, and the RL content in the RL-RH-M system alloy is The total RL-RH-M based alloy is 57 mass% or more and 82 mass% or less, the RH content is 13 mass% or more and 23 mass% or less of the entire RL-RH-M based alloy, and the M content is RL-. The total amount of the RH-M alloy is 5 mass% or more and 20 mass% or less, and the amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material in the diffusion step is 1 mass% or more and 2. It is 5 mass% or less.

In a certain embodiment, the amount of the RL-RH-M-based alloy adhered to the R-TB-based sintered magnet material in the diffusion step is 1.5 mass% or more and 2.5 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 shows the part of the RTB-based sintered magnet enlarged and schematically. It is sectional drawing which shows the inside of the broken line rectangular region of FIG. 1A by further enlarging. It is a flowchart which shows the example of the process in the manufacturing method of the RTB-based sintered magnet according to this disclosure.

First, the basic structure of the RTB-based sintered magnet according to the present disclosure will be described. The RT-B-based sintered magnet has a structure in which powder particles of a raw material alloy are bonded by sintering, and has a _{main phase mainly composed of R 2} T ₁₄ B compound particles and a grain boundary portion of the main phase. It is composed of grain boundary phases located in.

FIG. 1A is a cross-sectional view schematically showing an enlarged part of an RTB-based sintered magnet, and FIG. 1B is a cross-sectional view schematically showing the inside of the broken line rectangular region of FIG. 1A in an enlarged manner. Is. In FIG. 1A, as an example, an arrow having a length of 5 μm is shown for reference as a reference length indicating the size. As shown in FIGS. 1A and 1B, R-T-B based sintered magnet includes a main phase 12 mainly composed of _R 2 _{T 14} B compound, the grain boundary phase located grain boundary of the main phase 12 14 It is composed of and. Further, in the grain boundary phase 14, as shown in FIG. 1B, two R ₂ T ₁₄ B compound particles (grains) are adjacent to each other, and three R ₂ T ₁₄ B compound particles are adjacent to each other. Includes grain boundary triple points 14b. The typical main phase crystal grain size is 3 μm or more and 10 μm or less on average of the equivalent circle diameter of the magnet cross section. _{The R 2} T ₁₄ B compound, which is the main phase 12, is a ferromagnetic material having a 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 amount, T amount, and B amount in the raw material alloy _{are changed to the stoichiometric ratio of the R 2} T ₁₄ B compound (R amount: T amount: B amount = It should be close to 2:14: 1).
_{Further, by substituting a part of R of the R 2} T ₁₄ B compound which is the main phase with a heavy rare earth element such as Dy, Tb, Ho, the anisotropic magnetic field of the main phase can be increased while lowering the saturation magnetization. It has been known. In particular, the main phase outer shell in contact with the two-grain boundary phase tends to be the starting point of magnetization reversal, so heavy rare earth diffusion technology that can preferentially replace heavy rare earth elements with the main phase outer shell is efficient while suppressing the decrease in saturation magnetization. High H _cJ can be obtained.
On the other hand, it is known that _{high HcJ} can also be obtained by controlling the magnetism of the two-particle boundary phase 14a. Specifically, by lowering the concentration of magnetic elements (Fe, Co, Ni, etc.) in the two-grain boundary phase, the two-particle boundary phase is brought closer to non-magnetic, thereby forming a magnetic bond between the main phases. It can be weakened to suppress magnetization reversal.

In the method for producing an RTB-based sintered magnet according to the present disclosure, from the surface of the R-TB-based sintered magnet material to the inside of the magnet material through the grain boundary, together with the RH contained in the RL-RH-M-based alloy. , RL and M are diffused. As a result of the study by the present inventors, with respect to the RTB-based sintered magnet material prepared by preparing a fine powder sintered body having _{a particle size D 50 in the range of 2.0 μm to 3.5 μm.} , found that it is possible to while reducing expensive RH by performing spreading processing and the adhesion amount and the RH concentrations of RL-RH-M alloy in a narrow specific range, give a high B _r and high H _cJ ..

In the method for manufacturing an RTB-based sintered magnet according to the present disclosure, as shown in FIG. 2, the steps S10 for preparing the RTB-based sintered magnet material and the RL-RH-M-based alloy are prepared. Includes step S20. The order of the step S10 for preparing the RTB-based sintered magnet material and the step S20 for preparing the RL-RH-M alloy is arbitrary.
As shown in FIG. 2, the method for manufacturing an RTB-based sintered magnet according to the present disclosure further comprises RL-RH-M-based alloy on at least a part of the surface of the RTB-based sintered magnet material. Includes a diffusion step S30 in which at least a portion is adhered and heated at a temperature of 700 ° C. or higher and 1100 ° C. or lower in a vacuum or inert gas atmosphere. The amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material in the diffusion step S30 is 1 mass% or more and 2.5 mass% or less.

In the present disclosure, the RTB-based sintered magnet before and during the diffusing step is referred to as "RTB-based sintered magnet material", and the RTB-based firing after the diffusing step is used. The connecting magnet is simply referred to as "RTB-based sintered magnet".

(Step of preparing RTB-based sintered magnet material)
In the RTB-based 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 RTB-based. It is 27 mass% or more and 35 mass% or less of the whole sintered magnet material. T is at least one selected from the group consisting of Fe, Co, Al, Mn, and Si, and T always contains Fe, and the content of Fe with respect to the whole T is 80 mass% or more.
If R is less than 27 mass%, a liquid phase is not sufficiently formed 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: 0.80-1.20 mass%,
Ga: 0-1.0 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 mol ratio [T] / [B] of T to 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 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 the Fe content (80 mass% or more) with respect to the whole was divided by the atomic weight of each element, and the sum of these values [T] and the analytical value of B (mass%) were obtained. ) Divided by the atomic weight of B [B]. provided that mol ratio [T] / [B] is more than 14.0 shows that relatively B amount is small relative to the T amount used for the main phase _{(R 2 T 14} B compound) formed .. The mol ratio [T] / [B] is more preferably 14.3 or more and 15.0 or less. A higher H _cJ can be obtained. The B content is preferably 0.9 mass% or more and less than 1.0 mass% of the entire RTB-based sintered body.

The RTB-based sintered magnet material can be prepared by using a general method for manufacturing an RTB-based sintered magnet represented by an Nd-Fe-B-based sintered magnet. As an example, a raw material alloy produced by a strip casting method or the like _{is pulverized using a jet mill or the like to have a particle size D 50} of 2.0 μm or more and 3.5 μm or less, and then molded in a magnetic field at 900 ° C. or higher. A sintered body can be prepared by sintering at a temperature of 1100 ° C. or lower. If the particle size D ₅₀ is less than 2.0 μm, the productivity may be significantly deteriorated, and if it exceeds 3.5 μm, the desired effect may not be obtained even if the diffusion step of the present disclosure is performed. There is sex. It is considered that this is because the particle size of the powder is reflected in the crystal particle size of the sintered body, which also affects the diffusion. Preferably, the particle size D ₅₀ is 2.5 μm or more and 3.3 μm or less. While reducing the precious RH on that suppresses deterioration in productivity, it is possible to obtain a higher B _r and a high H _cJ. The D ₅₀ is a particle size in which the integrated particle size distribution (volume basis) from the small diameter side is 50% in the particle size distribution obtained by the laser diffraction method by the air flow dispersion method. Further, the D ₅₀ can be measured by using, for example, a particle size distribution measuring device “HELOS & RODOS” manufactured by Symbolec under the conditions of dispersion pressure: 4 bar, measurement range: R2, and measurement mode: HRLD.

(Step of preparing RL-RH-M alloy)
In the RL-RH-M alloy, RL is at least one of 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 RL. It is 57 mass% or more and 82 mass% or less of the whole −RH−M alloy. Examples of light rare earth elements 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 13 mass% or more and 23 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 5 mass% or more and 20 mass% or less of the entire RL-RH-M alloy. be. Typical examples of RL-RH-M alloys are TbNdPrCu alloy, TbNdCePrCu alloy, TbNdGa alloy, TbNdPrGaCu alloy and the like.

If the RL is less than 57 mass%, it becomes difficult for RH and M to be introduced into the R-TB-based sintered magnet material, and H _cJ may decrease. If the RL exceeds 82 mass%, the RL-RH-M may decrease. The alloy powder becomes very active during the manufacturing process of the system alloy. As a result, the alloy powder may be significantly oxidized or ignited. Preferably, the RL content is 70 mass% or more and 80 mass% or less of the entire RL-RH-M alloy. Higher H _cJ can be obtained.

If RH is less than 13 mass%, a high H _cJ improving effect by RH may not be obtained, and if it exceeds 23 mass%, the H _cJ improving effect by RL and M may decrease. Therefore, heavy rare earth elements while reducing the usage, it may be impossible to obtain a R-T-B based sintered magnet having a high B _r and high H _cJ. Preferably, the RH content is 13 mass% or more and 20 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 5 mass%, RL and RH are less likely to be introduced into the two-grain boundary phase, and H _cJ may not be sufficiently improved. If M is more than 20 mass%, the contents of RL and RH decrease and H _There is a possibility that cJ will not improve sufficiently. Preferably, the M content is 7 mass% or more and 15 mass% or less of the entire RL-RH-M alloy. Higher H _cJ can be obtained. Further, M preferably contains Ga, more preferably Cu, and a higher H _cJ can be obtained.

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

(Diffusion process)
At least a part of the prepared RL-RH-M alloy is attached to at least a part of the surface of the R-TB-based sintered magnet material prepared as described above, and a vacuum (non-oxidizing atmosphere) or an inert gas is attached. A diffusion step of heating at a temperature of 700 ° C. or higher and 1100 ° C. or lower is performed in an atmosphere. 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 surface of the sintered material via the grain boundaries in the RTB-based sintered magnet material. It is diffused and introduced inside. The amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material in the diffusion step is set to 1 mass% or more and 2.5 mass% or less. Thereby, a high H _cJ improvement effect can be obtained. When the amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material is less than 1 mass%, the amount of RH, RL, and M introduced into the magnet material is too small and high H _cJ. may not be obtained, it exceeds 2.5 mass%, _{B r} may be reduced. Preferably, the amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material is 1.5 mass% or more and 2.2 mass% or less. Higher H _cJ can be obtained. Further, the amount of RH adhered to the RTB-based sintered magnet material by the RL-RH-M-based alloy is preferably 0.1 mass% or more and 0.4 mass% or less. _Within this range, it is possible to obtain an RTB-based sintered magnet having a high HcJ while more reliably reducing the amount of heavy rare earth elements used. The amount of RH attached is the amount of RH attached to the R-TB-based sintered magnet material, and is the RH concentration in the RL-RH-M-based alloy and the R- of the RL-RH-M-based alloy. It can be calculated from the amount of adhesion of the TB-based sintered magnet material. The amount of RH adhered is defined by the mass ratio when the mass of the RTB-based sintered magnet material is 100 mass%.

If the heating temperature in the diffusion step is less than 700 ° C., the amount of the liquid phase containing RH, RL and M may be _{too small to obtain a high H cJ.} On the other hand, if the temperature exceeds 1100 ° C., H _cJ may decrease significantly. Preferably, the heating temperature in the diffusion step is 800 ° C. or higher and 1000 ° C. or lower. Higher H _cJ can be obtained. Further, preferably, the RTB-based sintered magnet subjected to the diffusion step (700 ° C. or higher and 1100 ° C. or lower) is cooled to 300 ° C. at a cooling rate of 15 ° C./min or higher from the temperature at which the diffusion step was carried out. It is preferable to cool it. Higher H _cJ can be obtained.

The diffusion step can be carried out by arranging an RL-RH-M alloy having an arbitrary shape on the surface of the RTB-based sintered magnet material and using a known heat treatment apparatus. For example, the surface of the R-TB-based sintered magnet material can be covered with a powder layer of an RL-RH-M alloy to perform a diffusion step. For example, a coating step of applying the pressure-sensitive adhesive to the surface to be coated and a step of adhering the RL-RH-M alloy to the region to which the pressure-sensitive adhesive is applied may be performed. Examples of the pressure-sensitive 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 preheated before coating. The purpose of preheating is to remove excess solvent to control the adhesive strength and to evenly adhere the adhesive. 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. Further, 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 form an RL-RH-M alloy and an RT. -A B-based sintered magnet material may be attached. Examples of the dispersion medium include alcohol (ethanol and the like), aldehydes and ketones. Further, as long as at least a part of the RL-RH-M alloy is attached to at least a part of the R-TB-based sintered magnet material, the arrangement position is not particularly limited, but RL-RH is preferable. The −M alloy is arranged so as to adhere to a surface at least perpendicular to the orientation direction of the RTB-based 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 R-TB-based sintered magnet material. It may be attached.

(Step of performing heat treatment)
Preferably, the temperature is 400 ° C. or higher and 750 ° C. or lower and lower than the temperature carried out in the diffusion step in a vacuum or an inert gas atmosphere with respect to the RTB-based sintered magnet in which the diffusion step is carried out. Heat treatment at temperature. By performing the heat treatment, a higher H _cJ can be obtained.

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 R-T-B-based sintered magnet material]
Each element was weighed so as to have the composition of the RTB-based sintered magnet material shown in No. 1 of Table 1, and a raw material alloy was prepared by a strip casting method. Each of the obtained alloys was coarsely pulverized by a hydrogen pulverization method to obtain a coarsely pulverized powder. Next, zinc stearate as a lubricant was added to the crude pulverized powder in an amount of 0.035 mass% based on 100 mass% of the crude powder and mixed. The coarsely pulverized powder containing the lubricant was finely pulverized by a jet mill under the conditions A and B described below.
Under condition A, _{fine powder having a particle size D 50} : 4.2 μm and a particle size D ₉₉ : 12.5 μm was obtained by pulverization. In addition, _{in the particle size distribution obtained by the laser diffraction method by the air flow dispersion method, the D 50} and D ₉₉ are from the particle size and the small particle size side in which the integrated particle size distribution (volume basis) from the small diameter side becomes 50%, respectively. The particle size is such that the integrated particle size distribution (volume basis) of is 99%. Further, D ₅₀ and D ₉₉ were measured by using a particle size distribution measuring device “HELOS & RODOS” manufactured by Symbolec under the conditions of dispersion pressure: 4 bar, measurement range: R2, and measurement mode: HRLD.
Condition B was finely pulverized so that the _{particle size D 50} : 3.3 μm and the particle size D _{99: 8.5 μm.}

Zinc stearate as a lubricant was added to each of the obtained finely pulverized powders A and B in an amount of 0.05 mass% based on 100 mass% of the finely pulverized powder, mixed, and then molded in a magnetic field to obtain a molded product. As the molding apparatus, a so-called right-angled magnetic field forming apparatus (transverse magnetic field forming apparatus) in which the magnetic field application direction and the pressurizing direction are orthogonal to each other was used. The obtained molded product was sintered in vacuum for 4 hours (selecting a temperature at which densification by sintering occurs sufficiently), and then rapidly cooled to obtain an RTB-based sintered magnet material. The density of the obtained RTB-based sintered magnet material was 7.5 Mg / m ³ or more.
High frequency induction of the content of Nd, Pr, Fe, Co, Al, Si, Ga, Cu, Zr, B in order to determine the components of the RTB-based sintered magnet material obtained from conditions A and B. It was measured by inductively coupled plasma emission spectroscopy (ICP-OES). A gas analyzer is used for the amount of oxygen in the RTB-based sintered magnet material by the gas melting-infrared absorption method, the amount of nitrogen by the gas melting-heat conduction method, and the amount of carbon by the sintering-infrared absorption method. Was measured. Both condition A and condition B had the same composition. The results of the analysis are shown in Table 1. The total components of the RTB-based sintered magnet material may not be 100 mass%. This is because the measurement method is different as described above, and because other elements may be contained as unavoidable impurities.

[Step of preparing RL-RH-M alloy]
Each element is weighed so as to have the composition of the RL-RH-M alloy shown in No. 1-A and 1-B of Table 2, the raw materials thereof are dissolved, and a ribbon or flakes are formed by a single roll ultra-quenching method. Obtained the alloy of. The composition of the obtained RL-RH-M alloy is shown in Table 2. Each component in Table 2 was measured using high frequency inductively coupled plasma emission spectroscopy.

[Diffusion process]
The RTB-based sintered magnet material of reference numeral 1 in Table 1 was cut and cut into a cube of 7.2 mm × 7.2 mm × 7.2 mm. PVA was applied to the entire surface of the processed RTB magnet material as an adhesive by a dipping method. Next, the RL-RH-M alloy was adhered to the entire surface of the RTB-based sintered magnet material coated with the adhesive under the production conditions shown in Table 3. The amount of RL-RH-M alloy adhered is determined by crushing the RL-RH-M alloy in an argon atmosphere using a mortar and then passing it through several types of sieves with a mesh size of 45 to 1000 μm to obtain RL having different particle sizes. It was adjusted by using a −RH—M based alloy. Then, using a vacuum heat treatment furnace, the RL-RH-M alloy and the RTB sintered magnet material are heated under the conditions shown in the diffusion step of Table 3 in a reduced pressure argon atmosphere controlled to 100 Pa. , Cooled.

[Step of performing heat treatment]
The RTB-based sintered magnet material heated in the diffusion step was heat-treated by heating at 500 ° C. in reduced pressure argon controlled to 100 Pa using a vacuum heat treatment furnace. The entire surface of each heat-treated sample was machined using a surface grinding machine to obtain a cube-shaped sample (RTB-based sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. .. The heating temperature of the RL-RH-M alloy and the RTB-based sintered magnet material in the diffusion step, and the heating of the R-TB-based sintered magnet in the step of performing the heat treatment after the diffusion step. The temperature was measured using a thermocouple.

[Sample evaluation]
The obtained sample was measured remanence B _r and coercivity H _cJ by B-H tracer. _Further , the difference ( _{ΔH cJ} ) between H cJ of the RTB-based sintered magnet material and H _cJ of the RTB-based sintered magnet after the diffusion step and the heat treatment step was determined. The results are shown in Table 3. In the experimental example, the amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material was 2.5 mass% or less, and the obtained R-TB-based sintered magnet was obtained. magnetic properties _B r: 1.35 T or _more, H cJ: _1925kA / m or more was evaluated as the present invention example. As shown in Table 3, the RL-RH having the composition shown by reference numerals 1-A and 1-B in Table 2 is used using the RTB-based sintered magnet material obtained from the finely pulverized powder obtained under the above condition B. Sample No. of the example of the present invention using the −M alloy. 1-4～1-6 can obtain a high _{B r} and high _{H cJ,} further △ _{H cJ} seen that even higher. On the other hand, an R-TB-based sintered magnet material obtained from the finely pulverized powder pulverized under the above condition A was used, and RL-RH-M having the compositions shown by reference numerals 1-A and 1-B in Table 2 was used. Sample No. using a system alloy. In 1-1 through 1-3, _{H cJ} compared to invention sample is low, indicating the effect of the diffusion step and the heat treatment step △ _{H cJ} is low.

Experimental Example 2
[Step of preparing R-T-B-based sintered magnet material]
Each element was weighed so as to have the composition of the RTB-based sintered magnet material shown by reference numeral 2 in Table 4, and a raw material alloy was prepared by a strip casting method. Each of the obtained alloys was coarsely pulverized by a hydrogen pulverization method to obtain a coarsely pulverized powder. Next, zinc stearate as a lubricant was added to the coarsely pulverized powder in an amount of 0.035 mass% based on 100 mass% of the crude powder and mixed to obtain a lubricant-containing finely pulverized powder. The obtained coarsely pulverized lubricant-containing powder was pulverized using a jet mill device to obtain a finely pulverized powder having _{a particle size D 50} of 3.3 _{μm and D 99: 8.5 μm.}
Zinc stearate as a lubricant was added to the obtained finely ground powder in an amount of 0.05 mass% based on 100 mass% of the finely ground powder, mixed, and then molded in a magnetic field to obtain a molded product. As the molding apparatus, a so-called right-angle magnetic field forming apparatus (transverse magnetic field forming apparatus) in which the magnetic field application direction and the pressurizing direction are orthogonal to each other was used.
The obtained molded product was sintered in vacuum for 4 hours (selecting a temperature at which densification by sintering occurs sufficiently), and then quenching was performed to obtain a sintered magnet material. The density of the obtained RTB-based sintered magnet material was 7.5 Mg / m ³ or more.
The results of the obtained RTB-based sintered magnet material are shown in Table 4. Each component in Table 4 was measured by the same method as in Experimental Example 1.

[Step of preparing RL-RH-M alloy]
Each element is weighed so as to have the composition of the RL-RH-M alloy shown by reference numerals 2-A, 2-B, 2-C in Table 5, the raw materials thereof are dissolved, and a single roll ultra-quenching method is performed. Obtained a ribbon or flaky alloy. The composition of the obtained RL-RH-M alloy is shown in Table 5. Each component in Table 5 was measured by high frequency inductively coupled plasma emission spectroscopy.

[Diffusion process]
The RTB-based sintered magnet material of reference numeral 2 in Table 4 was cut and cut into a cube of 7.2 mm × 7.2 mm × 7.2 mm. PVA was applied to the entire surface of the processed RTB magnet material as an adhesive by a dipping method. Next, the RL-RH-M alloy was adhered to the entire surface of the RTB-based sintered magnet material coated with the adhesive under the production conditions shown in Table 6. The amount of the RL-RH-M alloy adhered is determined by crushing the RL-RH-M alloy in an argon atmosphere using a mortar and then passing it through several types of sieves having a mesh size of 45 to 1000 μm to obtain a particle size. It was adjusted by using different RL-RH-M alloys. and. After heating the RL-RH-M alloy and the RTB sintered magnet material under the conditions shown in the diffusion step in Table 6 in a reduced pressure argon atmosphere controlled to 100 Pa using a vacuum heat treatment furnace, Cooled.

[Step of performing heat treatment]
The RTB-based sintered magnet material after the diffusion step was heat-treated by heating at 490 ° C. in reduced pressure argon controlled to 100 Pa using a vacuum heat treatment furnace. The entire surface of each heat-treated sample was machined using a surface grinding machine to obtain a cube-shaped sample (RTB-based sintered magnet) of 7.0 mm × 7.0 mm × 7.0 mm. .. 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 R-TB system in the step of performing the heat treatment after the diffusion step. The heating temperature of the sintered magnet was measured using a thermocouple. The heating temperatures of the RL-RH-M alloy and the RTB sintered magnet material in the diffusion step were all 900 ° C. × 10H as in Experimental Example 1.

[Sample evaluation]
As shown in Table 6, sample No. In 2-1~2-4, RL-RH-M alloy coating weight was a comparison of _{B r} and _{H cJ} in the range of less than 1.6mass%. Sample No. in which the RH amount of the RL-RH-M alloy is less than 13 mass%. Although 2-1 In high B _r is obtained, a high H _cJ can not be obtained. On the other hand, the sample No. which is an example of the present invention. 2-2 to 2-4 in the high _{B r} and a high _{H cJ} is obtained together.

Claims (2)

A sintered body is prepared from fine powder having a particle size D ₅₀ of 2.0 μm to 3.5 μm, and an RTB-based sintered magnet material (R is a rare earth element, and is composed of a group consisting of Nd, Pr and Ce. A step of preparing at least one selected, T being at least one selected from the group consisting of Fe, Co, Al, Mn, and Si, and T always containing Fe).
RL-RH-M alloys (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, where RH is from Tb, Dy and Ho. At least one selected from the group consisting of, and M is at least one selected from the group consisting of Cu, Ga, Fe, Co, Ni, and Al).
At least a part of the RL-RH-M alloy is adhered to at least a part of the surface of the RTB-based sintered magnet material, and the temperature is 700 ° C. or higher and 1100 ° C. or lower in a vacuum or an inert gas atmosphere. Diffusion process that heats at temperature and
Including
In the RTB-based sintered magnet material, the R content is 27 mass% or more and 35 mass% or less of the entire RTB-based sintered magnet material, and the Fe content with respect to the entire T is 80 mass%. That's it,
In the RL-RH-M alloy, the RL content is 57 mass% or more and 82 mass% or less of the entire RL-RH-M alloy, and the RH content is 13 mass of the entire RL-RH-M alloy. % Or more and 23 mass% or less, and the M content is 5 mass% or more and 20 mass% or less of the entire RL-RH-M alloy.
The amount of the RL-RH-M alloy adhered to the RTB-based sintered magnet material in the diffusion step is 1 mass% or more and 2.5 mass% or less.
A method for manufacturing an RTB-based sintered magnet. The R-. A method for manufacturing a TB-based sintered magnet.

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