CN113950728B - Rare earth sintered magnet and rotary electric machine using the same - Google Patents
Rare earth sintered magnet and rotary electric machine using the same Download PDFInfo
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- CN113950728B CN113950728B CN201980097353.9A CN201980097353A CN113950728B CN 113950728 B CN113950728 B CN 113950728B CN 201980097353 A CN201980097353 A CN 201980097353A CN 113950728 B CN113950728 B CN 113950728B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/02—Details of the magnetic circuit characterised by the magnetic material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
- B23K26/146—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor the fluid stream containing a liquid
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/64—Electric machine technologies in electromobility
Abstract
The rare earth sintered magnet has R 2 T 14 And a rare earth sintered magnet in which the B phase, R is at least one selected from Nd, pr, dy and Tb, and T is at least one selected from Fe and Co, wherein the cut surface of the rare earth sintered magnet has: a moiety having R and O as main components; and a T-rich portion having a higher concentration of T than the portion mainly composed of R and O, wherein the area ratio of the T-rich portion to the cutting area of the rare earth sintered magnet is 5 to 30%.
Description
Technical Field
The present invention relates to a rare earth sintered magnet and a rotary electric machine using the same.
Background
The rare earth sintered magnet is produced by compacting a raw material powder for a magnet in a magnetic field and then sintering the compacted raw material powder. Since the rare earth sintered magnet has large sintering shrinkage and poor dimensional accuracy, it is necessary to perform grinding or the like after sintering. However, the magnetic characteristics of the rare earth sintered magnet are often degraded due to the influence of the processing.
In order to prevent deterioration of magnetic characteristics, patent document 1 proposes cutting a neodymium magnet by irradiating the neodymium magnet with a solid laser having a fundamental wave with a wavelength of 1000 to 1100 nm.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2009-000732
Disclosure of Invention
Problems to be solved by the invention
However, the following problems exist: even if the rare earth sintered magnet is subjected to cutting processing by the method of patent document 1, a decrease in magnetic characteristics is observed in the obtained rare earth sintered magnet.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rare earth sintered magnet in which a decrease in magnetic characteristics due to cutting processing performed after sintering is suppressed.
Means for solving the problems
The invention relates to a rare earth sintered magnet, which has R 2 T 14 A rare earth sintered magnet in which phase B and R are at least one selected from Nd, pr, dy and Tb, and T is at least one selected from Fe and Co, and a cut surface of the rare earth sintered magnet: having a moiety comprising R and O as main components; and a T-rich portion having a higher concentration of T than the portion mainly composed of R and O, wherein the area ratio of the T-rich portion to the cutting area of the rare earth sintered magnet is 5 to 30%.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide a rare earth sintered magnet in which a decrease in magnetic characteristics due to cutting processing performed after sintering is suppressed.
Drawings
Fig. 1 is a schematic configuration diagram of a processing device used for cutting a rare earth sintered magnet according to an embodiment of the present invention.
Fig. 2 is a schematic configuration diagram of a processing device used for cutting a rare earth sintered magnet according to an embodiment of the present invention.
Fig. 3 is a front view showing a configuration of a rotor of a rotary electric machine according to an embodiment of the present invention.
Fig. 4 is a front view showing a structure of a stator of a rotary electric machine according to an embodiment of the present invention.
Fig. 5 is a group image and element map of the cut surface of the rare earth sintered magnet of example 1.
Fig. 6 is a diagram emphasizing the T-rich portion of the group imaging and element mapping shown in fig. 5.
Fig. 7 is a group image and element map of the cut surface of the rare earth sintered magnet of comparative example 1.
Fig. 8 is a comparison result of the oxygen level in the cut surface of the rare earth sintered magnet of example 1 and the oxygen level in the cut surface of the rare earth sintered magnet of comparative example 1.
Fig. 9 is a group image and element map of the cut surface of the rare earth sintered magnet of comparative example 2.
Fig. 10 is a Dy map obtained by EPMA analysis of the cut surface of the rare earth sintered magnet of example 1 from the side.
Fig. 11 is a Dy map obtained by EPMA analysis of the cut surface of the rare earth sintered magnet of comparative example 1 from the side.
Fig. 12 shows an example of the evaluation result of the magnetic characteristics of the rare earth sintered magnet.
Detailed Description
The rare earth sintered magnet according to embodiment 1 is produced by a method comprising the steps of 2 T 14 The B-phase rare earth sintered magnet is obtained by performing a specific cutting process. Wherein R is at least one selected from Nd (neodymium), pr (praseodymium), dy (dysprosium) and Tb (terbium). T is at least one selected from Fe (iron) and Co (cobalt). From the viewpoint of magnetic characteristics, R preferably contains Nd as an essential component, and a part of Nd is substituted with at least one selected from Pr, dy, and Tb. From the viewpoint of magnetic characteristics, T is preferably composed of Fe as an essential component, and a part of Fe is preferably replaced with Co. The rare earth sintered magnet before the cutting process can be produced by compacting a raw material powder for a rare earth sintered magnet in a magnetic field according to a known method and then sintering the compacted raw material powder. In addition, R-containing rare earth sintered magnet can be used as the rare earth sintered magnet before cutting 2 T 14 Commercial rare earth sintered magnets of phase B.
Fig. 1 and 2 are schematic configuration diagrams of a processing device used for cutting the rare earth sintered magnet according to the present embodiment.
In fig. 1, the processing apparatus includes: a laser oscillator 1, a reflecting mirror 2, a collecting lens 3, a processing head 4, a pump 5, and a processing table 6. The processing head 4 includes: a nozzle for injecting water supplied from the pump 5 to the workpiece. Further, a rare earth sintered magnet 7 as a workpiece is disposed on the processing table 6. In the processing apparatus of FIG. 1, the laser beam is obtained from a YAG laser oscillator or CO 2 The laser beam 8 emitted from the laser oscillator 1 such as a laser oscillator is reflected by the reflecting mirror 2, collected by the collecting lens 3, and sent to the processing head 4. The water supplied from the pump 5 is ejected from a nozzle provided in the processing head 4 to form a water column 9. The laser beam 8 sent to the processing head 4 travels in the water column 9 and irradiates the rare earth sintered magnet 7. The rare earth sintered magnet 7 is irradiated with the laser beam 8 while water is sprayed in this manner, thereby performing the cutting process.
In fig. 2, the processing apparatus includes: a laser oscillator 1, a reflecting mirror 2, a collecting lens 3, a water jet nozzle 10, a pump 5, and a processing table 6. Water is supplied from the pump 5 to the water injection nozzle 10. Further, a rare earth sintered magnet 7 as a workpiece is disposed on the processing table 6. In the processing apparatus of fig. 2, although not shown, the water jet nozzle 10 and the rare earth sintered magnet 7 as the object to be processed are immersed in water. In the processing apparatus of fig. 2, the laser light 8 emitted from the laser oscillator 1 is reflected by the reflecting mirror 2 and then collected by the collecting lens 3, but the laser light travels through water, not shown, and irradiates the rare earth sintered magnet 7. The water supplied from the pump 5 is sprayed from the water spray nozzle 10 onto the workpiece. The rare earth sintered magnet 7 is irradiated with the laser beam 8 while water is sprayed in this manner, thereby performing the cutting process.
In the case of using, for example, a YAG laser, the wavelength of the laser light 8 that irradiates the rare earth sintered magnet 7 can be set to 1064nm as a fundamental wavelength or 532nm as a second harmonic. The laser output is not limited, and may be in the range of 10W to 2000W. The apertures of the nozzle provided in the processing head 4 and the water jet nozzle 10 are not limited, and may be in the range of 20 μm to 500 μm. If the apertures of the nozzle provided in the processing head 4 and the water jet nozzle 10 are within the above-described ranges, the rare earth sintered magnet 7 can be suitably cut without being significantly damaged. The water jet pressure is preferably in the range of 1MPa to 50MPa, more preferably in the range of 5MPa to 40MPa, from the viewpoint of performing cutting processing by the laser beam 8 and simultaneously forming a cut surface having a specific tissue. If the water jet pressure is less than 1MPa, the water may be insufficiently supplied to the processing portion, and a cut surface having a specific tissue may not be formed. On the other hand, if the water injection pressure exceeds 50MPa, the fixation of the rare earth sintered magnet 7 may become difficult. In the water used for the cutting process, from the viewpoint of preventing corrosion of the rare earth sintered magnet 7, it is preferable to remove at least chloride ions, and for example, pure water such as distilled water or ion-exchanged water, ultrapure water, or the like can be used. The water temperature during the cutting process may be in the range of 5 to 50 ℃ as long as the laser light 8 is stable. In view of workability, the water temperature at the time of cutting is preferably 15 to 35 ℃.
The cut surface of the rare earth sintered magnet 7 obtained by performing the above-described cutting process has: a moiety having R and O as main components; and a T-rich portion having a higher concentration of T than a portion mainly composed of R and O. The thicknesses of the R and O-based portions and the T-rich portions formed on the cut surface (the depth from the cut surface) are preferably 0.1 μm to 25. Mu.m, more preferably 0.5 μm to 10. Mu.m. If the thicknesses of the portion mainly composed of R and O and the T-rich portion are within the above-described range, the decrease in magnetic characteristics can be further suppressed. The area ratio of the T-rich portion is 5% to 30%, preferably 10% to 20%, of the cutting area of the rare earth sintered magnet 7. The R and O-based portions and the T-rich portion of the cut surface of the rare earth sintered magnet can be determined by elemental analysis using an electron probe microanalyzer (Electron Probe Micro Analyzer; EPMA). If the area ratio of the T-rich portion is within the above range, the decrease in magnetic characteristics due to the dicing process is suppressed.
From the viewpoint of both corrosion resistance and mechanical strength, the T-rich portion preferably contains Fe and Co. When the rare earth sintered magnet 7 containing Dy is used as the work, the Dy concentration in the range of 0.5 μm to 7 μm from the cut surface of the rare earth sintered magnet 7 in the depth direction is higher than the Dy concentration in the range of more than 7 μm from the cut surface of the rare earth sintered magnet 7 in the depth direction, in other words, the Dy concentration layer may be present in the range of 0.5 μm to 7 μm from the cut surface of the rare earth sintered magnet 7 in the depth direction. Even if a Dy concentrated layer easily coexisting with the T-rich portion is present, no problem arises in the mechanical strength of the rare earth sintered magnet 7. The Dy enriched layer is likely to suppress the decrease in coercive force of the rare earth sintered magnet 7 after the dicing process. In the T-rich portion, other elements than Dy, which are previously incorporated in the rare earth sintered magnet 7, may be incorporated as minor components. Examples of such other elements include B, C, N, al, si, P, S, ti, mn, ni, cu, zn, ga, ge, zr, pr, nb, nd, tb, la, sm.
The rare earth sintered magnet 7 obtained by the above-described cutting process may be subjected to additional surface treatment in order to improve corrosion resistance. Examples of the additional surface treatment include chemical conversion treatments such as phosphoric acid, chromic acid, zirconium-based, titanate-based, manganese-based, and silicate-based treatments, and surface treatments using hydrofluoric acid. The rare earth sintered magnet 7 may be coated with a coating film of epoxy, polyester, acrylic, amideimide, polyimide, silicone, zinc-rich paint containing zinc flakes, alkyl silicate, fluororesin, or the like, as required. The rare earth sintered magnet 7 may be formed as a powder coating film, an electrodeposition coating film, a vapor deposition film of parylene (parylene), or the like, as necessary. The rare earth sintered magnet 7 may be formed with an aluminum vapor deposition film, an aluminum alloy vapor deposition film, a TiN film, or a metal film by vacuum vapor deposition, sputtering, or wet method, as required. Examples of the metal-based coating film using the wet method include nickel plating, copper plating, tin plating, zinc plating, tin alloy plating, zinc alloy plating, fine particle-containing metal plating, electroless ni—p plating, and electroless ni—b plating. In addition, the rare earth sintered magnet 7 may be subjected to a treatment for forming an oxide, nitride, or the like.
In the present embodiment, the cutting process of the rare earth sintered magnet 7 includes chamfering, partial sizing, and punching.
According to embodiment 1, a rare earth sintered magnet in which a decrease in magnetic characteristics due to cutting processing performed after sintering is suppressed can be provided. In addition, the rare earth sintered magnet according to embodiment 1 has a small decrease rate of magnetic characteristics with an increase in operating temperature, and has a good square ratio.
The rotating electrical machine according to embodiment 2 includes: a rotor and a stator using the rare earth sintered magnet according to embodiment 1 described above. Fig. 3 is a front view showing a structure of a rotor of a rotary electric machine according to embodiment 2. In fig. 3, the rotor includes a rotor core 11 and a rare earth sintered magnet 7. The rotor core 11 is formed by stacking a plurality of steel plates. In the center of the rotor core 11, a shaft hole 12 is formed. The rare earth sintered magnet 7 is inserted into a plurality of magnet insertion holes provided in the circumferential direction of the rotor core 11.
According to embodiment 2, since the rare earth sintered magnet having excellent magnetic characteristics is incorporated into the rotor, the rotary electric machine can be made more efficient, smaller, and the like.
The rotating electrical machine according to embodiment 3 includes: a stator and a rotor using the rare earth sintered magnet according to embodiment 1 described above are used. Fig. 4 is a front view showing a structure of a stator of a rotary electric machine according to embodiment 3. In fig. 4, the stator includes a stator core 13 and a rare earth sintered magnet 7. The stator core 13 is formed by laminating a plurality of steel plates. The rare earth sintered magnet 7 is mounted in a magnet mounting groove provided in the inner peripheral surface of the stator core 13.
According to embodiment 3, since the rare earth sintered magnet having excellent magnetic characteristics is incorporated in the stator, the rotary electric machine can be made more efficient, smaller, and the like.
In embodiments 2 and 3, examples of the binder used for fixing the rare earth sintered magnet 7 include epoxy-based, acrylic-based, urethane-based, phenolic-based, cyanoacrylate-based, silicone-based, amideimide-based, hot melt-based, polyimide-based, modified silicone-based, and organic resin components used for coating. The curing method of these adhesives is not limited, and examples thereof include heat curing, room temperature curing, moisture curing, UV curing, electron beam curing, and the like. In addition, a resin such as a thermoplastic resin or a liquid crystal polymer other than the thermosetting resin may be used to fix the rare earth sintered magnet 7.
Examples
Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
Example 1 >
According to a known method, a sheet having a size of 12.5mm by 60mm, a thickness of 4.5mm and R 2 T 14 A rare earth sintered magnet in which B phase, R is Nd and Dy, and T is Fe and Co. In the rare earth sintered magnet, the thickness direction is set to be an easy magnetization direction.
The rare earth sintered magnet was fixed to a processing table of a processing apparatus shown in fig. 1, and the rare earth sintered magnet was cut into a rare earth sintered magnet having a size of 7mm×7mm and a thickness of 1mm by a laser beam having a wavelength of 532nm emitted from a YAG laser oscillator and a water jet having a jet pressure of 30MPa and a water temperature of 20 to 25 ℃, and then washed with water and dried to obtain a rare earth sintered magnet of example 1. In the rare earth sintered magnet after the cutting process, the thickness direction is set to be an easy magnetization direction.
Example 2 >
According to a known method, a sheet having a size of 12.5mm by 60mm, a thickness of 4.5mm and R 2 T 14 A rare earth sintered magnet in which B phase, R is Nd and Dy, and T is Fe and Co. In the rare earth sintered magnet, the thickness direction is set to be an easy magnetization direction.
The rare earth sintered magnet was fixed to a processing table of a processing apparatus shown in fig. 2, immersed in water at a water temperature of 20 to 25 ℃, and cut into a rare earth sintered magnet having a size of 7mm×7mm and a thickness of 1mm by a laser beam having a wavelength of 1064nm emitted from a YAG laser oscillator, a jet pressure of 8MPa and a water temperature of 20 to 25 ℃ by a water jet, and then washed with water and dried to obtain a rare earth sintered magnet of example 2. In the rare earth sintered magnet after the cutting process, the thickness direction is set to be an easy magnetization direction.
Comparative example 1 >
According to a known method, a sheet having a size of 12.5mm by 60mm, a thickness of 4.5mm and R 2 T 14 A rare earth sintered magnet in which B phase, R is Nd and Dy, and T is Fe and Co. In the rare earth sintered magnet, the thickness direction is set to be an easy magnetization direction.
The rare earth sintered magnet was cut into a rare earth sintered magnet having a size of 7mm×7mm and a thickness of 1mm by using a diamond grindstone while pouring water, and then washed with water and dried to obtain a rare earth sintered magnet of comparative example 1.
Comparative example 2 >
According to a known method, a sheet having a size of 12.5mm by 60mm, a thickness of 4.5mm and R 2 T 14 A rare earth sintered magnet in which B phase, R is Nd and Dy, and T is Fe and Co. In the rare earth sintered magnet, the thickness direction is set to be an easy magnetization direction.
The rare earth sintered magnet of comparative example 2 was obtained by cutting the rare earth sintered magnet into a rare earth sintered magnet having a size of 7mm×7mm and a thickness of 1mm, washing with water, and drying in the same manner as in example 2, except that water was stirred instead of spraying water.
FIG. 5 shows a composition image (COMPO image) obtained by analyzing the cut surface of the rare earth sintered magnet of example 1 by a scanning electron microscope (Scanning Electron Microscope: SEM) and an elemental mapping obtained by analyzing the cut surface by a Field Emission electron probe microscopy (Field Emission-Electron Probe Micro Analyzer: FE-EPMA).
As is clear from the composition imaging shown in fig. 5, the cut surface of the rare earth sintered magnet of example 1 is in a state of wavy white portions and gray portions. From a comparison of the group images and element maps shown in fig. 5, it is known that: the white part of the group image is mainly Nd, dy, and O, and only a small amount of Fe and Co are detected in this part. On the other hand, it is known that: the gray part of the group image shows higher Fe and Co concentrations than the white part, and only a small amount of Nd, dy, and O are detected in this part. In the group imaging and element mapping shown in fig. 5, a portion where the concentration of Fe and Co increases is emphasized as a T-rich portion, which is shown in fig. 6. If the comparison is made at the detection level of the element map, fe and Co are detected 2 times or more in the T-rich portion than in the portion other than the T-rich portion, specifically, the portion mainly composed of Nd, dy, and O. The T-rich portion was considered to exist from a circular portion having a diameter of 0.5 μm to a portion having a diameter of 20 μm×10 μm, as judged by gray portions imaged with the composition.
In the rare earth sintered magnet of example 1, the area ratio of the T-rich portion was 10% with respect to the cut area. In the rare earth sintered magnet of example 2, the area ratio of the T-rich portion was 17% relative to the cut area.
Fig. 7 is an elemental mapping obtained by analyzing the cut surface of the rare earth sintered magnet of comparative example 1 with a scanning electron microscope and by analyzing the cut surface with a field emission electron probe microscopic analyzer.
As is clear from the composition imaging shown in fig. 7, the undulation state was not found in the cut surface of the rare earth sintered magnet of comparative example 1. From the element map shown in fig. 7, it is known that: nd, dy and Fe are distributed on the whole cutting surface.
Fig. 8 is a result of comparing the detection level of oxygen in the cut surface of the rare earth sintered magnet of example 1 with the detection level of oxygen in the cut surface of the rare earth sintered magnet of comparative example 1. In comparison of the ratios present, the signal ratios of the corresponding elements using a field emission electron probe microanalyzer were used. The measurement was performed under the following conditions using a field emission electron probe microanalyzer (JXA-8530F, manufactured by Japanese electric Co., ltd.).
Acceleration voltage: 15.0kV
Irradiation current: 5.014e-008A
Irradiation time: 10ms of
Number of pixels: 512 pixels by 512 pixels
Multiplying power: 2000 times
Cumulative number of times: 1 time
Beam diameter: 1 μm
In fig. 8, the vertical axis represents the presence ratio of elements, and the horizontal axis represents the detection level of oxygen. The values of the points were multiplied to calculate the average value of the oxygen detection level in the cut surface of the rare earth sintered magnet of example 1 and the average value of the oxygen detection level in the cut surface of the rare earth sintered magnet of comparative example 1, respectively. The average value of the oxygen detection level was 74.0 in example 1 and 36.9 in comparative example 1. From this result, it was found that: in the cut surface of the rare earth sintered magnet of example 1, oxygen is present significantly more than in the cut surface of the rare earth sintered magnet of comparative example 1.
Fig. 9 is a group image obtained by analyzing the cut surface of the rare earth sintered magnet of comparative example 2 by a scanning electron microscope and an elemental mapping obtained by analyzing the cut surface by a field emission electron probe microscopic analyzer.
As is clear from the composition imaging shown in fig. 9, fine spherical materials and powdery materials were adhered to the cut surface of the rare earth sintered magnet of comparative example 2. From the element map shown in fig. 9, it is known that: these deposits mainly include Fe and O, and less Nd and Dy.
Fig. 10 is a Dy map obtained by analyzing the cut surface of the rare earth sintered magnet of example 1 from the side using a field emission electron probe microanalyzer. From the Dy map shown in fig. 10, it is known that: dy concentration in the range of 0.5 μm to 7 μm from the cut surface toward the depth direction is higher than Dy concentration in the range of more than 7 μm from the cut surface toward the depth direction.
Further, the detection signal of Dy in the Dy map was binarized, and quantitative comparison was attempted by the brightness at the time of 256 division. It can be said that the ratio of Dy is large when the luminance is high, and the ratio of Dy is small when the luminance is low. The Dy binarization level at this time is shown in FIG. 10. Dy binarization level was 140.4 in the range of 0.5 μm to 7 μm from the cut surface of the rare earth sintered magnet of example 1 toward the depth direction. On the other hand, dy binarization level in the range exceeding 7 μm from the cut surface of the rare earth sintered magnet of example 1 toward the depth direction was 107.0.
In addition, dy binarization level was 110.5 in the range of 0.5 μm to 7 μm from the cut surface of the rare earth sintered magnet of example 2 toward the depth direction. On the other hand, dy binarization level in the range exceeding 7 μm from the cut surface of the rare earth sintered magnet of example 2 toward the depth direction was 103.1.
Fig. 11 is a Dy map obtained by analyzing the cut surface of the rare earth sintered magnet of comparative example 1 from the side using a field emission electron probe microanalyzer. From the Dy map shown in fig. 11, in the rare earth sintered magnet of comparative example 1, no Dy concentrated layer was found as seen in the rare earth sintered magnet of example 1. The detection signal of Dy in the Dy map was binarized, and quantitative comparison was attempted using the brightness at 256 divisions. The Dy binarization level at this time is shown in FIG. 11. Dy binarization level was 101.6 in the range of 0.5 μm to 7 μm from the cut surface of the rare earth sintered magnet of comparative example 1 toward the depth direction. On the other hand, dy binarization level in the range exceeding 7 μm from the cut surface of the rare earth sintered magnet of comparative example 1 toward the depth direction was 115.4.
From the results shown in fig. 5 to 11, the following will be known.
In comparative example 2, since water was not injected during irradiation with laser light, it is considered that Fe, nd and Dy were separated from each other at the stage of forming the cut surface, and a large amount of fine particles mainly composed of Fe and O were adhered to the cut surface. In comparative example 2, the area ratio of the microparticle coating was 51% relative to the cut area.
In example 1, since the rare earth sintered magnet was cut by irradiating laser light while spraying water, it is considered that: the components constituting the rare earth sintered magnet are dissolved and collected together with the re-precipitation of the cut surface, thereby forming a cut surface having a specific composition. The cut surface has a portion mainly composed of Nd, dy, and O, and a portion rich in Fe and Co. A small amount of fine particles of 0.3 μm to 5 μm were also observed on the cut surface of the rare earth sintered magnet of example 1. Consider that: since the particles adhering to the cut surface are small, the decrease in magnetic characteristics is suppressed. In example 1, the area ratio of the microparticle coating was 1% or less relative to the cutting area.
In example 1, it was found that: dy-concentrated layers are formed in a specific range from the cutting surface toward the depth direction. It is assumed that this is due to: in the stage of forming the cut surface, deposition of Dy preferentially occurs.
Next, the magnetic characteristics of the rare earth sintered magnets obtained in examples 1 and 2 and comparative examples 1 and 2 were evaluated. Fig. 12 shows an example of the evaluation result of the magnetic characteristics. In FIG. 12, the vertical axis represents the magnetic flux density [ T ], and the horizontal axis represents the magnetic field [ MA/m ]. The coercive force of the rare earth sintered magnet in operation is an important index. The magnetic field corresponding to the point (90% Br) of the magnetic flux density which becomes 90% of the maximum magnetic flux density Br is set to coercive force Hk, and the maximum magnetic flux density Br and coercive force Hk of each rare earth sintered magnet are shown in table 1. The maximum magnetic flux density Br and coercive force Hk were evaluated at 23℃and 90℃respectively.
TABLE 1
| Example 1 | Example 2 | Comparative example 1 | Comparative example 2 | |
| Br [ T ] at 23 DEG C] | 1.314 | 1.314 | 1.335 | 1.212 |
| Br [ T ] at 90 DEG C] | 1.254 | 1.225 | 1.256 | 1.147 |
| Hk [ MA/m ] at 23 DEG C] | 1.225 | 1.225 | 1.259 | - |
| Hk [ MA/m ] at 90 DEG C] | 0.740 | 0.701 | 0.675 | - |
As is clear from table 1, the maximum magnetic flux density Br and coercive force Hk of the rare earth sintered magnets of examples 1 and 2 were slightly lower than those of the rare earth sintered magnet of comparative example 1 at 23 ℃. The maximum magnetic flux density Br of the rare earth sintered magnets of examples 1 and 2 was equal to the maximum magnetic flux density Br of the rare earth sintered magnet of comparative example 1 at 90 ℃. Further, the coercive force Hk of the rare earth sintered magnets of examples 1 and 2 was higher than that of the rare earth sintered magnet of comparative example 1 at 90 ℃. On the other hand, in the rare earth sintered magnet of comparative example 2, the maximum magnetic flux density Br was significantly reduced due to the influence of the cutting process.
Production example of rotor
A rare earth sintered magnet having a size of 5mm X10 mm and a thickness of 1.2mm was cut in the same manner as in example 1, and then washed with water and dried. In the rare earth sintered magnet after the cutting process, the thickness direction is set to be an easy magnetization direction.
A plurality of silicon steel plates with the diameter of 200mm and the thickness of 0.2mm are laminated and then riveted to manufacture the rotor core with the thickness of 60 mm. In the circumferential direction of the rotor core, 16 magnet insertion holes of 1.3mm×5.1mm are provided. At the center of the rotor core, a shaft hole is formed. 6 rare earth sintered magnets fabricated in the foregoing were inserted into the magnet insertion holes 1. A room temperature-curable two-component acrylic adhesive (CEMEDINE co., ltd. Y611 black S) was filled in the gap between the magnet insertion holes into which the rare earth sintered magnet was inserted, and the rare earth sintered magnet was bonded to the rotor core. Then, the shaft was pressed into the shaft hole to obtain a rotor with embedded magnets (Interior Permanent Magnet: IPM).
Production example of stator
A rare earth sintered magnet having a size of 5mm by 10mm and a thickness of 1.2mm was produced by the same method as in example 1 by a near net shape forming method. Then, the burrs and protrusions of the rare earth sintered magnet were removed and size-processed in the same manner as in example 2. In the rare earth sintered magnet, the thickness direction is set to be an easy magnetization direction.
After a plurality of silicon steel sheets with the thickness of 0.2mm are laminated, riveting is performed to manufacture a stator core with the thickness of 40 mm. A through hole having an inner diameter of 160mm was provided in the center of the stator core. A magnet mounting groove of 1.3mm×5.1mm is provided at 8 places on the inner peripheral surface of the through hole. For the magnet mounting groove 1, 4 rare earth sintered magnets manufactured in the front are mounted, and a permanent magnet type stator is obtained. For mounting the rare earth sintered magnet, a room temperature curing type two-liquid acrylic adhesive (CEMEDINE co., ltd. Y611 black S) was used.
Description of the reference numerals
1 laser oscillator, 2 reflector, 3 collecting lens, 4 processing head, 5 pump, 6 processing table, 7 rare earth sintered magnet, 8 laser, 9 water column, 10 water jet nozzle, 11 rotor core, 12 shaft hole, 13 stator core
Claims (5)
1. A rare earth sintered magnet is provided with R 2 T 14 B phase, R is at least one selected from Nd, pr, dy and Tb, T is at least one rare earth sintered magnet selected from Fe and Co, wherein,
the cut surface of the rare earth sintered magnet has: a moiety having R and O as main components; and a T-rich portion having a higher concentration of T than the portion mainly composed of R and O,
the area ratio of the T-rich part relative to the cutting area of the rare earth sintered magnet is 5% -30%.
2. A rare earth sintered magnet as claimed in claim 1, wherein said T-rich portion contains Fe and Co.
3. The rare earth sintered magnet according to claim 1 or 2, wherein a concentration of Dy in a range of 0.5 μm to 5 μm from a cut surface of the rare earth sintered magnet toward a depth direction is higher than a concentration of Dy in a range of more than 5 μm from the cut surface of the rare earth sintered magnet toward the depth direction.
4. A rotating electrical machine is provided with:
a rotor comprising a rotor core formed by stacking steel plates and the rare earth sintered magnet according to any one of claims 1 to 3 inserted into a magnet insertion hole provided in the rotor core; and
and a stator.
5. A rotating electrical machine is provided with:
a stator including a stator core formed by stacking steel plates, and the rare earth sintered magnet according to any one of claims 1 to 3 attached to an inner peripheral surface of the stator core;
and a rotor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2019/024049 WO2020255240A1 (en) | 2019-06-18 | 2019-06-18 | Rare earth sintered magnet and rotating electrical machine using same |
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| Publication Number | Publication Date |
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| CN113950728A CN113950728A (en) | 2022-01-18 |
| CN113950728B true CN113950728B (en) | 2023-07-04 |
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| CN201980097353.9A Active CN113950728B (en) | 2019-06-18 | 2019-06-18 | Rare earth sintered magnet and rotary electric machine using the same |
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| Country | Link |
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| JP (1) | JP6625299B1 (en) |
| CN (1) | CN113950728B (en) |
| DE (1) | DE112019007471T5 (en) |
| WO (1) | WO2020255240A1 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009000732A (en) * | 2007-06-25 | 2009-01-08 | Mitsubishi Materials Corp | Neodymium magnet machining method |
| JP2009054754A (en) * | 2007-08-27 | 2009-03-12 | Hitachi Metals Ltd | R-fe-b based rare earth sintered magnet and manufacturing method thereof |
| CN107622853A (en) * | 2016-07-15 | 2018-01-23 | Tdk株式会社 | R T B based rare earth element permanent magnets |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5074929A (en) * | 1989-08-28 | 1991-12-24 | General Motors Corporation | Method of making a permanent magnet sensor element with a soft magnetic layer |
| JPH0462813A (en) * | 1990-06-25 | 1992-02-27 | Daihen Corp | Method for producing amorphous magnetic alloy wound core |
| JP2005198365A (en) * | 2003-12-26 | 2005-07-21 | Neomax Co Ltd | Rare earth permanent magnet for motor, and its manufacturing method |
| JP5013430B2 (en) * | 2008-06-18 | 2012-08-29 | 株式会社スギノマシン | Laser processing equipment |
| JP6848735B2 (en) * | 2016-07-15 | 2021-03-24 | Tdk株式会社 | RTB series rare earth permanent magnet |
| JP6743549B2 (en) * | 2016-07-25 | 2020-08-19 | Tdk株式会社 | R-T-B system sintered magnet |
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2019
- 2019-06-18 DE DE112019007471.7T patent/DE112019007471T5/en active Pending
- 2019-06-18 CN CN201980097353.9A patent/CN113950728B/en active Active
- 2019-06-18 WO PCT/JP2019/024049 patent/WO2020255240A1/en active Application Filing
- 2019-06-18 JP JP2019547328A patent/JP6625299B1/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009000732A (en) * | 2007-06-25 | 2009-01-08 | Mitsubishi Materials Corp | Neodymium magnet machining method |
| JP2009054754A (en) * | 2007-08-27 | 2009-03-12 | Hitachi Metals Ltd | R-fe-b based rare earth sintered magnet and manufacturing method thereof |
| CN107622853A (en) * | 2016-07-15 | 2018-01-23 | Tdk株式会社 | R T B based rare earth element permanent magnets |
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| Publication number | Publication date |
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| CN113950728A (en) | 2022-01-18 |
| DE112019007471T5 (en) | 2022-03-10 |
| WO2020255240A1 (en) | 2020-12-24 |
| JPWO2020255240A1 (en) | 2021-09-13 |
| JP6625299B1 (en) | 2019-12-25 |
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