Bonded magnet and preparation method and application thereof

Abstract

The invention provides a bonded magnet as well as a preparation method and application thereof. The bonded magnet comprises at least two substrates, a bonding layer is arranged between any two adjacent base bodies, and a bonding layer is arranged between the two base bodies. The bonding layer comprises an insulating bonding agent and micro-beads; the D50 particle size of the microbeads is 10 [mu] m or more and less than 90 [mu] m; the coercive force of the surface layer of the matrix is higher than the coercive force of the interior of the matrix; wherein the surface layer of the base body is a surface layer adjacent to the bonding layer and / or a surface layer opposite to the bonding layer. The bonded magnet has excellent coercive force, and has excellent eddy current loss resistance and heat resistance when being applied to a motor.

Description

Technical Field

[0001] The present invention relates to an adhesive magnet, a preparation method thereof, and an application thereof. Background Art

[0002] Neodymium iron boron rare earth permanent magnets have been widely used in new energy vehicles, intelligent communication, wind power generation and other fields. In recent years, neodymium iron boron magnets have been continuously improved and have more excellent magnetic properties. Especially, due to their strong magnetic field intensity, high coercivity, and high temperature resistance, they are widely used in permanent magnet motors. However, as a permanent magnet material, it still has certain defects.

[0003] In the application of motors, with the increase of motor speed or power, there is an eddy current effect in the neodymium iron boron magnet, which will further cause the temperature to rise. In the worst case, it may lead to the demagnetization of the neodymium iron boron magnet material, thus greatly reducing the performance of the motor. In the prior art, generally, most of the permanent magnets of motors use neodymium iron boron materials with high coercivity and remanence. Their conductivity is high and their heat resistance is poor. Compared with copper loss and iron loss, the eddy current loss of permanent magnets is not large in most cases. However, for high-speed, high-power density motors and motors with a closed structure, the eddy current loss of neodymium iron boron permanent magnets will cause a large temperature rise in the rotor part, and even cause irreversible demagnetization of the permanent magnet in severe cases, which is fatal to permanent magnet motors.

[0004] Therefore, there is a need for a magnet that can effectively reduce eddy current loss and improve heat resistance without affecting the use of the motor. Summary of the Invention

[0005] In order to overcome the defects of serious eddy current loss and poor heat resistance when the magnets in the prior art are applied to motors, the present application provides an adhesive magnet, a preparation method thereof, and an application thereof. The adhesive magnet has excellent coercivity, and when it is applied to a motor, the anti-eddy current loss effect and heat resistance effect are excellent.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides an adhesive magnet, which includes at least two substrates; an adhesive layer is provided between any two adjacent substrates;

[0008] The adhesive layer includes an insulating adhesive and microbeads; the D50 particle size of the microbeads is more than 10 μm and less than 90 μm;

[0009] The coercivity of the surface layer of the substrate is higher than that of the interior of the substrate; wherein, the surface layer of the substrate is the surface layer adjacent to the adhesive layer and / or the surface layer opposite to the adhesive layer.

[0010] In the present invention, for any substrate, the surface layer adjacent to the adhesive layer means the area with a perpendicular distance of 1 mm or less from the surface adjacent to the adhesive layer, which is defined as the surface layer adjacent to the adhesive layer; the surface layer opposite to the adhesive layer means the area with a perpendicular distance of 1 mm or less from the surface opposite to the adhesive layer, which is defined as the surface layer opposite to the adhesive layer; the remaining part of any substrate is defined as the interior of the substrate.

[0011] In the present invention, preferably, the difference between the coercivity of the surface layer of the substrate and the coercivity of the interior of the substrate is ≥ 0.5 kOe.

[0012] In the present invention, preferably, the coercivity of the surface layer of the substrate is ≥ 18.5 kOe, such as 25.02 kOe, 25.03 kOe, 25.05 kOe, 25.07 kOe, 25.08 kOe, 25.09 kOe, 25.1 kOe, 25.11 kOe, 25.12 kOe or 25.19 kOe.

[0013] In the present invention, preferably, the coercivity of the interior of the substrate is ≥ 18 kOe, such as 23.02 kOe, 23.04 kOe, 23.05 kOe, 23.08 kOe, 23.09 kOe, 23.12 kOe, 23.15 kOe, 23.16 kOe, 23.17 kOe or 23.53 kOe.

[0014] In the present invention, preferably, the substrate is a cuboid or a cube.

[0015] In the present invention, preferably, the surface layer of the substrate is the surface layer adjacent to the adhesive layer and the surface layer opposite to the adhesive layer.

[0016] Wherein, when the surface layer of the substrate is the surface layer adjacent to the adhesive layer and the surface layer opposite to the adhesive layer, the coercivity of the surface layer of the substrate is the average value of the coercivities of the surface layer adjacent to the adhesive layer and the surface layer opposite to the adhesive layer.

[0017] In the present invention, preferably, the coercivity distribution of the surface layer adjacent to the adhesive layer and the surface layer opposite to the adhesive layer in the substrate is the same.

[0018] In the present invention, preferably, the substrate is a neodymium iron boron magnet, and the definition of "neodymium iron boron" can be conventional in the art, which refers to a class of permanent magnet materials that at least include neodymium element, iron element and boron element and inevitable impurities.

[0019] In the present invention, preferably, the material of the microbeads includes ceramic materials and / or glass materials.

[0020] Among them, preferably, the ceramic material includes one or more of metal oxides, carbides, nitrides, and borides. Among them, the meaning of carbide is a binary compound formed by carbon and an element (except hydrogen) with an electronegativity smaller than or similar to it; the meaning of nitride is a binary compound formed by nitrogen and an element with an electronegativity smaller than it; the meaning of boride is a binary compound formed by boron and a metal or certain non-metals (such as carbon).

[0021] Among them, the metal oxide includes, for example, alumina (Al2O3) and / or zirconia (ZrO2).

[0022] Among them, the carbide includes, for example, silicon carbide (SiC) and / or boron carbide (B4C).

[0023] Among them, the nitride includes, for example, silicon nitride (Si3N4) and / or aluminum nitride (AlN).

[0024] Among them, the boride includes, for example, zirconium boride (ZrB2) and / or silicon boride (SiB6).

[0025] Among them, preferably, the glass material includes one or more of Na2SiO3, CaSiO3, SiO2, Na2O·CaO·6SiO2, K2O, CaO, and B2O3.

[0026] In some preferred embodiments of the present invention, the material of the microbeads is alumina (Al2O3).

[0027] In some preferred embodiments of the present invention, the material of the microbeads is silicon carbide (SiC).

[0028] In some preferred embodiments of the present invention, the material of the microbeads is zirconium boride (ZrB2).

[0029] In the present invention, preferably, the D50 particle size of the microbeads is 20 - 40 μm or 50 - 70 μm.

[0030] In the present invention, preferably, the shape of the microbeads is one or more of spherical, polygonal, elliptical, and bar-shaped.

[0031] Among them, the spherical shape can be a regular sphere and / or an irregular sphere.

[0032] Among them, the polygon can be a regular polygon and / or an irregular polygon.

[0033] In the present invention, preferably, the material of the microbeads is a ceramic material, and the density of the microbeads is less than 1.5 g / cm 3 , for example, 1.2 g / cm 3 .

[0034] In the present invention, preferably, the material of the microbeads is a glass material, and the density of the microbeads is greater than 2.5 g / cm 3 , for example, 1.2 g / cm 3 .

[0035] In the present invention, preferably, the roundness of the microbeads is 0.4 - 1, for example, 0.6. Among them, the roundness can reflect the degree of similarity between the projected area of the microbeads and a circle. Considering the smoothness of the perimeter comprehensively, it is defined as the ratio of the minimum radius and the maximum radius of the microbeads. The minimum radius is the minimum straight-line distance from the centroid of the microbeads to the surface, and the maximum radius is the maximum straight-line distance from the centroid of the microbeads to the surface.

[0036] In the present invention, preferably, the types of the insulating adhesive include one or more of epoxy resin, cyanoacrylate, unsaturated polyester resin, phenolic resin, and polyimide resin.

[0037] In the present invention, preferably, in any one of the adhesive layers, the mass percentage of the microbeads in the adhesive layer is 0.1% - 5%, for example, 1%.

[0038] In the present invention, preferably, in any one of the adhesive layers, the mass percentage of the insulating adhesive in the adhesive layer is 95% - 99.9%, for example, 99%.

[0039] In the present invention, preferably, the mass percentage of the adhesive layer in the substrate is less than 2% and not zero, for example, 0.12%.

[0040] In the present invention, preferably, the thicknesses of the respective adhesive layers are independently 20 - 100 μm. The meaning of the thickness of the adhesive layer is the vertical distance between the two adjacent side surfaces of the adhesive layer and the substrate.

[0041] In the present invention, preferably, the bonded magnet includes at least three substrates and adhesive layers respectively disposed between two adjacent substrates.

[0042] Among them, preferably, the standard deviation σt of the seam width t of different adhesive layers is < 10, and σt is, for example, 3.1, 3.2, 3.3, 3.4, 3.5, 3.7, or 4.1.

[0043] In the present invention, the seam width t of any one of the adhesive layers is the thickness of any one of the adhesive layers, and the meaning of the thickness of the adhesive layer is the vertical distance between the two adjacent side surfaces of the adhesive layer and the substrate.

[0044] Among them, preferably, in any one of the adhesive layers, the seam width t is 1 - 3 times the D50 particle size of the microbeads.

[0045] Preferably, in any one of the bonding layers, the width t of the glue seam is 20-100 μm, for example, 50-90 μm.

[0046] In the present invention, preferably, the resistance at both ends of the bonding layer is ≥0.1 MΩ, for example, >20 MΩ, where the meaning of both ends of the bonding layer refers to the two side surfaces adjacent to the substrate of the bonding layer.

[0047] In the present invention, preferably, the bonded magnet includes 3-100 substrates.

[0048] The present invention also provides a method for preparing a bonded magnet, which includes the following steps:

[0049] Apply an insulating bonding paste between any two adjacent substrates and then perform a curing treatment to form a bonding layer between the two adjacent substrates;

[0050] The coercivity of the two surfaces of the substrate adjacent to or opposite to the bonding layer is higher than the coercivity inside the substrate;

[0051] Among them, the insulating bonding paste includes an insulating binder and microbeads; the D50 particle size of the microbeads is more than 10 μm and less than 90 μm;

[0052] Among them, the pressure of the curing treatment is 0.5-2.5 Mpa.

[0053] In the present invention, preferably, the substrate is a neodymium iron boron magnet.

[0054] In the present invention, preferably, the number of the substrates is 2-100, more preferably 3-100.

[0055] In the present invention, the method for preparing the intermediate green body can be a conventional preparation method in the art, for example, including the following steps:

[0056] S1. Melting: Put the raw materials into a melting furnace according to the formula and perform vacuum melting to obtain an alloy sheet;

[0057] S2. Hydrogen crushing: Hydrogenate and dehydrogenate the above alloy sheet in a hydrogen atmosphere and then cool to obtain coarse powder;

[0058] S3. Jet milling: Jet mill the coarse powder in step S2 in an atmosphere with an oxygen gas content of 200 ppm or less to obtain fine powder;

[0059] S4. Orientation forming: Perform orientation forming on the fine powder in step S3;

[0060] S5. Sintering: Sinter the product after step S4 in a vacuum or inert gas atmosphere to obtain a green compact;

[0061] S6. Cutting: Cut the blank obtained in step S5 to obtain an intermediate blank.

[0062] In certain specific embodiments of the present invention, in step S1, the hydrogen crushing is performed using a hydrogen crushing furnace.

[0063] Preferably, in step S3, the content of the oxidation gas is 100 ppm.

[0064] Preferably, in step S3, the jet milling includes jet milling the coarse powder and the lubricant in step S2 in an atmosphere with an oxidation gas content of 200 ppm or less to obtain fine powder.

[0065] The lubricant is, for example, tributyl borate.

[0066] The mass percentage of the lubricant in the mass of the coarse powder is 0.3% or less, more preferably 0.04% - 0.12%, for example 0.1%.

[0067] Preferably, in step S3, the D50 particle size of the fine powder is 3.9 - 4.4 μm.

[0068] Preferably, in step S4, the magnetic field strength for the orientation forming is 1.5 T or more.

[0069] Preferably, in step S4, it further includes adding an antioxidant to the fine powder and then performing orientation forming.

[0070] Preferably, the antioxidant includes alkanes.

[0071] The mass percentage of the antioxidant in the mass of the fine powder is 0.3% or less, more preferably 0.04% - 0.12%, for example 0.1%.

[0072] Preferably, in step S5, the sintering temperature is 1040 - 1100 °C.

[0073] Preferably, in step S5, the sintering time is 4 - 12 h, for example 8 h.

[0074] Preferably, in step S6, the cutting can be performed along the length direction and / or the width direction of the blank. The length direction and the width direction are both perpendicular to the orientation direction.

[0075] Preferably, in step S6, the intermediate blank is cut into an intermediate blank with a length of 2 - 40 mm and / or a width of 2 - 40 mm, for example an intermediate blank with a length of 2 - 20 mm and / or a width of 2 - 20 mm.

[0076] In the present invention, preferably, the method for preparing the substrate comprises the following steps:

[0077] Diffusion sources are applied to two opposite surfaces of the intermediate blank, and after heat treatment and tempering treatment in sequence, a substrate is obtained.

[0078] Among them, preferably, the method for applying the diffusion source includes sputtering, evaporation coating, coating, printing or electrodeposition.

[0079] Among them, preferably, the diffusion source includes one or more of heavy rare earth simple substances, alloys containing heavy rare earths, hydrides containing heavy rare earths, fluorides containing heavy rare earths, and oxides containing heavy rare earths.

[0080] Among them, the heavy rare earths are, for example, Dy and / or Tb.

[0081] Among them, preferably, the temperature of the heat treatment is 710 - 1000 °C, for example, 900 °C.

[0082] Among them, preferably, the time of the heat treatment is 5 - 50 h, for example, 20 h.

[0083] Among them, preferably, the temperature of the tempering treatment is 400 - 600 °C, for example, 500 °C.

[0084] Among them, preferably, the time of the tempering treatment is 2 - 8 h, more preferably 3 - 6 h, for example, 5 h.

[0085] Among them, preferably, the application amount of the diffusion source is 0.5% - 1%, for example, 0.6%. Herein, the meaning of the application amount is the mass percentage of the diffusion source in the mass of the intermediate blank.

[0086] In some specific embodiments of the present invention, after the tempering treatment, a surface degreasing step is further included to obtain the substrate.

[0087] Among them, surface grinding can be performed before the surface degreasing step. Among them, diamond grinding wheels can be used for the surface grinding.

[0088] Among them, the surface degreasing includes, for example, phosphating treatment and degreasing in sequence.

[0089] Among them, preferably, the phosphating treatment is to soak the intermediate blank in a phosphating solution, and the phosphating solution is a composite phosphating solution.

[0090] Among them, preferably, the degreasing is to soak the intermediate blank in a degreasing solution, and the degreasing solution includes degreasing powder.

[0091] In some specific embodiments of the present invention, the mass content of the degreasing powder in the degreasing solution is 2%.

[0092] In certain specific embodiments of the present invention, the types of the degreasing powder are one or more of sodium carbonate, sodium silicate, sodium bicarbonate, surfactant, and sodium hydroxide.

[0093] In certain specific embodiments of the present invention, the degreasing is to soak the intermediate green body in a degreasing solution, and the degreasing solution includes ethanol and isopropanol.

[0094] In the present invention, there is no particular limitation on the time of the phosphating treatment and the degreasing, as long as the surface of the substrate has no rust and grease.

[0095] Among them, before the phosphating treatment, a mechanical processing step may further be included.

[0096] In the present invention, preferably, the difference between the coercive force of two faces of the substrate adjacent to or opposite to the adhesive layer and the coercive force inside the substrate is ≥ 0.5 kOe.

[0097] In the present invention, preferably, the coercive force of two faces of the substrate adjacent to or opposite to the adhesive layer is ≥ 18.5 kOe, such as 25.02 kOe, 25.03 kOe, 25.05 kOe, 25.07 kOe, 25.08 kOe, 25.09 kOe, 25.1 kOe, 25.11 kOe, 25.12 kOe, or 25.19 kOe.

[0098] In the present invention, preferably, the coercive force inside the substrate is ≥ 18 kOe, such as 23.02 kOe, 23.04 kOe, 23.05 kOe, 23.08 kOe, 23.09 kOe, 23.12 kOe, 23.15 kOe, 23.16 kOe, 23.17 kOe, or 23.53 kOe.

[0099] Those skilled in the art generally understand that in order to achieve curing between two substrates, the direction of the pressure applied during the curing treatment is perpendicular to the direction of the adhesive layer.

[0100] In the present invention, preferably, the temperature of the curing treatment is 100 - 250 °C.

[0101] In the present invention, preferably, the curing treatment includes a first heating section and a second heating section, the temperature of the first heating section is 100 - 250 °C, and the temperature of the second heating section is higher than that of the first heating section.

[0102] Among them, preferably, the pressure of the first heating section is 0.5 - 2.5 Mpa, such as 2 Mpa.

[0103] Among them, preferably, the time of the first heating stage is 0.1 - 6 h, for example, 1 h.

[0104] In some specific embodiments of the present invention, the temperature of the first heating stage is 120 °C.

[0105] Among them, preferably, the temperature of the second heating stage is 150 - 250 °C, for example, 160 °C.

[0106] Among them, preferably, the pressure of the second heating stage is 0.5 - 2.5 Mpa, for example, 2 Mpa.

[0107] Among them, preferably, the time of the second heating stage is 0.1 - 6 h, for example, 1 h.

[0108] In some specific embodiments of the present invention, after the curing treatment, it further includes the steps of machining and surface treatment.

[0109] Among them, the machining can process the bonded magnet into a target size.

[0110] Among them, the surface treatment includes, for example, phosphating treatment or spraying epoxy resin.

[0111] In the present invention, preferably, the material of the microbeads includes ceramic material and / or glass material.

[0112] Among them, preferably, the ceramic material includes one or more of metal oxides, carbides, nitrides, and borides. Among them, the meaning of carbide is a binary compound formed by carbon and an element (except hydrogen) with an electronegativity smaller than or close to it; the meaning of nitride is a binary compound formed by nitrogen and an element with an electronegativity smaller than it; the meaning of boride is a binary compound formed by boron and a metal, some non-metals (such as carbon).

[0113] Among them, the metal oxide includes, for example, alumina (Al2O3) and / or zirconia (ZrO2).

[0114] Among them, the carbide includes, for example, silicon carbide (SiC) and / or boron carbide (B4C).

[0115] Among them, the nitride includes, for example, silicon nitride (Si3N4) and / or aluminum nitride (AlN).

[0116] Among them, the boride includes, for example, zirconium boride (ZrB2) and / or silicon boride (SiB6).

[0117] Among them, preferably, the glass material includes one or more of Na2SiO3, CaSiO3, SiO2, Na2O·CaO·6SiO2, K2O, CaO, and B2O3.

[0118] In certain preferred embodiments of the present invention, the material of the microbeads is alumina (Al2O3).

[0119] In some specific embodiments of the present invention, the method for preparing the microbeads is as follows:

[0120] Mix the Al2O3 powder, binder and dispersant, and successively carry out ball milling, heat atomization, screening, sintering, and ball milling to form alumina ceramic microbeads, wherein the sintering temperature is 1300 - 1500 °C.

[0121] Among them, the binder is, for example, polyvinyl alcohol.

[0122] Among them, the dispersant is, for example, polyacrylic acid.

[0123] In certain preferred embodiments of the present invention, the material of the microbeads is silicon carbide (SiC).

[0124] In certain preferred embodiments of the present invention, the material of the microbeads is zirconium boride (ZrB2).

[0125] In the present invention, preferably, the D50 particle size of the microbeads is 20 - 40 μm or 50 - 70 μm.

[0126] In the present invention, preferably, the material of the microbeads is a ceramic material, and the density of the microbeads is less than 1.5 g / cm 3 , for example, 1.2 g / cm 3 .

[0127] In the present invention, preferably, the material of the microbeads is a glass material, and the density of the microbeads is greater than 2.5 g / cm 3 , for example, 1.2 g / cm 3 .

[0128] In the present invention, preferably, the roundness of the microbeads is 0.4 - 1, for example, 0.6. Among them, the roundness can reflect the degree of similarity between the projected area of the microbeads and a circle. Considering the smoothness of the perimeter comprehensively, it is defined as the ratio of the minimum radius and the maximum radius of the microbeads. The minimum radius is the minimum straight-line distance from the centroid of the microbeads to the surface, and the maximum radius is the maximum straight-line distance from the centroid of the microbeads to the surface.

[0129] In the present invention, preferably, the shape of the microbeads is one or more of spherical, polygonal, elliptical, and bar-shaped.

[0130] Among them, the spherical shape can be a regular sphere and / or an irregular sphere.

[0131] Among them, the polygon can be a regular polygon and / or an irregular polygon.

[0132] In the present invention, preferably, the types of the insulating adhesive include one or more of epoxy resin, cyanoacrylate, unsaturated polyester resin, phenolic resin, and polyimide resin.

[0133] In the present invention, the mass percentages of the components in the insulating adhesive paste are the same as those of the components in the adhesive layer, and the material loss during the curing process can be ignored.

[0134] In the present invention, preferably, the mass percentage of the microbeads in the insulating adhesive paste is 0.1% - 5%, for example, 1%.

[0135] In the present invention, preferably, the mass percentage of the insulating adhesive in the insulating adhesive paste is 95% - 99.9%, for example, 99%.

[0136] In the present invention, preferably, the mass percentage of the insulating adhesive paste in the matrix is less than 2%, for example, 0.12%.

[0137] The present invention also provides an adhesive magnet prepared by the preparation method of the above-mentioned adhesive magnet.

[0138] The present invention also provides an application of the above-mentioned adhesive magnet in an electric motor.

[0139] On the basis of conforming to the common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0140] The reagents and raw materials used in the present invention are all commercially available.

[0141] The positive and progressive effects of the present invention are as follows:

[0142] The adhesive magnet of the present invention includes a matrix and an adhesive layer. The adhesive layer includes an insulating adhesive and microbeads, which can control the width of the glue seam within a certain size, avoid the conduction caused by the infinite reduction of the glue seam, and prevent the phenomenon of non-insulation of the glue seam. The adhesive magnet of the present invention combines the adhesive layer with a matrix having a specific coercivity distribution, so that the adhesive magnet has excellent anti-eddy current loss effect and heat resistance effect.

[0143] In addition, the adhesive magnet of the present invention can effectively reduce the usage amount of heavy rare earths on the premise that the coercivity of the adhesive magnet meets the requirements; at the same time, it can also improve the production efficiency and material utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0144] Figure 1 It is a schematic structural diagram of the adhesive magnet of Example 1.

[0145] Figure 2Coercivity distribution diagram along the length direction of the bonded magnet assembly of Example 9.

[0146] Figure 3 Coercivity distribution diagram along the length direction of the bonded magnet assembly of Comparative Example 1.

[0147] Figure 4 Coercivity distribution diagram along the length direction of the bonded magnet assembly of Comparative Example 3. Detailed implementation manners

[0148] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0149] The manufacturers and models of the products used in the following examples and comparative examples are as follows:

[0150] Phosphating solution: The type is a composite phosphating solution, the manufacturer is Aier Chemical, and the model is AE;

[0151] Insulating adhesive: The type is epoxy resin, the manufacturer is Tianshan, and the model is 9322;

[0152] Lubricant: The type is tributyl borate, the manufacturer is Ningbo Haotian New Materials, and the model is Ningbo 0#;

[0153] Antioxidant: The type is alkane, the manufacturer is Tianjin Yueshengxing New Materials, and the model is Tianjin 3#;

[0154] Degreasing powder: The type is a mixture of sodium carbonate, sodium silicate, sodium bicarbonate, surfactant and sodium hydroxide, the manufacturer is Ensen, and the model is EFC-142T;

[0155] Microspheres: The type is alumina ceramic, the manufacturer is Jinlong Rare Earth Co., Ltd. which is self-produced, and the shape of the microspheres is spherical.

[0156] Among them, the preparation method of the alumina ceramic microspheres is as follows:

[0157] Mix Al2O3 powder, adhesive (type is polyvinyl alcohol) and dispersant (type is polyacrylic acid), and form alumina ceramic microspheres through ball milling, heating atomization, screening, sintering, and ball milling in sequence. Among them, the sintering temperature is 1300 - 1500 °C. After sintering, the adhesive and dispersant are removed.

[0158] Example 1

[0159] The preparation method of the intermediate blank of Example 1 is as follows:

[0160] S1. Melting: Put the raw materials into a melting furnace according to the formula and conduct vacuum melting to obtain alloy sheets; the formula is listed in Table 1:

[0161] Table 1

[0162]

[0163] S2. Hydrogen crushing: Use a hydrogen crushing furnace to successively hydrogenate and dehydrogenate the above alloy sheets in a hydrogen atmosphere and then cool to obtain coarse powder;

[0164] S3. Jet milling: After the coarse powder is stirred and mixed, the coarse powder in step S2 and the lubricant are subjected to jet milling in an atmosphere with an oxygen gas content of 100 ppm to obtain fine powder with a D50 particle size of 3.9 - 4.4 μm; the mass percentage of the lubricant in the coarse powder is 0.1%;

[0165] S4. Orientation forming: Add an antioxidant to the fine powder in step S3, mix evenly, and conduct orientation forming under the condition of a magnetic field strength of 1.5 T; the mass percentage of the antioxidant in the fine powder is 0.1%;

[0166] S5. Sintering: Sinter the product after step S4 under vacuum to obtain a blank; the sintering temperature is 1040 - 1100 °C, and the sintering time is 8 h;

[0167] S6. Cutting: Cut the blank in step S5 along the length direction of the blank to obtain an intermediate blank; the size of the intermediate blank is L = 40.0 mm, W = 8.1 mm, T = 37.5 mm; among them, the direction along T is the orientation direction, the direction along L is the length direction, and the direction along W is the width direction.

[0168] The preparation method of the bonded magnet in Example 1 is as follows:

[0169] Grain boundary diffusion treatment:

[0170] Conduct grain boundary diffusion treatment on the above intermediate blank, specifically: Coat the two L×T surfaces of the above intermediate blank with Tb element, and the application amount of Tb element on each surface of any substrate is 0.6%, conduct heat treatment at 900 °C for 20 h, and then conduct tempering treatment at 500 °C for 5 h. After completion, use a diamond grinding wheel to grind the two L×T surfaces of the intermediate blank after grain boundary diffusion treatment (the purpose of grinding is to grind to the specified size according to the width of the glue joint to ensure that the required size is reached after curing).

[0171] Surface degreasing:

[0172] The intermediate blank after the above-mentioned grain boundary diffusion treatment is successively subjected to phosphating treatment and degreasing to obtain a substrate without rust and grease on the surface; the phosphating solution used for phosphating treatment is a composite phosphating solution, and the degreasing solution used for degreasing is a degreasing powder with a mass content of 2%.

[0173] Curing treatment:

[0174] Mix the insulating adhesive and microbeads with a D50 particle size of 20 - 40 μm, a density of 1.2 g / cm 3 ³, and a roundness of 0.6 to form an insulating adhesive paste. Apply the insulating adhesive paste between the L×T surfaces of any adjacent 4 of the above-mentioned substrates and then carry out curing treatment to form an adhesive layer between two adjacent substrates; the mass percentage of the microbeads in the adhesive layer (i.e., the mass percentage of the microbeads in the insulating adhesive paste) is 1%, and the mass percentage of the insulating adhesive in the adhesive layer (i.e., the mass percentage of the insulating adhesive in the insulating adhesive paste) is 99%; the mass percentage of the adhesive layer in the substrate (i.e., the percentage of the mass of the substrate) is 0.12%.

[0175] Among them, the application direction of the pressure during the curing treatment is perpendicular to the direction of the adhesive layer; the above-mentioned curing treatment includes a first heating section and a second heating section. The temperature of the first heating section is 120 °C, and the time is 1 h. The temperature of the second heating section is 160 °C, and the time is 1 h; the pressure in both the first heating section and the second heating section is 2 Mpa.

[0176] After the curing treatment is completed and cooled to room temperature, a bonded magnet with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 37.5 mm is formed. Then, the bonded magnet is cut along the direction perpendicular to the orientation direction to form 4 bonded magnet assemblies with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm, and the width of the glue seam (i.e., the thickness of the adhesive layer) is observed using an optical microscope. Among them, the structural schematic diagram of the bonded magnet is as Figure 1 shown, which includes a substrate 1 and an adhesive layer 2 respectively arranged between two adjacent substrates. Among them Figure 1 is only for example and does not represent the actual number of bonded blocks.

[0177] Among them, the surface coercivity and the internal coercivity of any one substrate are equal, and their distributions are also equal. The surface layer of the substrate is the surface layer adjacent to the adhesive layer and the surface layer opposite to the adhesive layer. The coercivity of the surface layer of the substrate is the average coercivity of the surface layer adjacent to the adhesive layer and the surface layer opposite to the adhesive layer. The magnetic flux of the bonded magnet assembly, the surface coercivity and the internal coercivity of any one substrate are listed in Table 2.

[0178] Example 2

[0179] In step S6 of Example 2, an intermediate blank with dimensions of L = 40.0 mm, W = 4.1 mm, and T = 37.5 mm is cut and formed;

[0180] Curing treatment:

[0181] Apply insulating adhesive paste between the L×T surfaces of any adjacent 8 substrates, and then carry out curing treatment. After the curing treatment is completed, cool down to room temperature. Then cut the bonded magnet perpendicular to the orientation direction to form 8 segments of bonded magnet assemblies with dimensions of L = 40.0 mm, W = 32 mm, and T = 2.5 mm.

[0182] Other conditions are the same as those in Example 1.

[0183] Example 3

[0184] In step S6 of Example 3, an intermediate blank with dimensions of L = 20.1 mm, W = 8.1 mm, and T = 37.5 mm is cut and formed;

[0185] Grain boundary diffusion treatment:

[0186] Carry out grain boundary diffusion treatment on the above intermediate blank. Specifically: Coat the two L×T surfaces and the two W×T surfaces of the above intermediate blank with Tb element. The application amount of Tb element on each of the above surfaces of any one substrate is 0.6%. Conduct heat treatment at 900 °C for 20 h, and then conduct tempering treatment at 500 °C for 5 h. After completion, use a diamond grinding wheel to grind the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment.

[0187] Curing treatment:

[0188] Apply insulating adhesive paste between the W×T surfaces of any adjacent 2 of the above substrates to form an intermediate body, and then apply insulating adhesive paste between the L×T surfaces of any adjacent 4 intermediate bodies and then carry out curing treatment. After the curing treatment is completed, cool down to room temperature to form a bonded magnet with 2 segments bonded in the length direction and 4 segments bonded in the width direction. Then cut the bonded magnet perpendicular to the orientation direction to form 8 segments of bonded magnet assemblies with dimensions of L = 40.0 mm, W = 32 mm, and T = 2.5 mm.

[0189] Other conditions are the same as those in Example 1.

[0190] Example 4

[0191] In step S6 of Example 4, an intermediate blank with dimensions of L = 20.1 mm, W = 4.1 mm, and T = 37.5 mm is cut and formed;

[0192] Grain boundary diffusion treatment:

[0193] The above intermediate blank is subjected to grain boundary diffusion treatment, specifically: Tb element is coated on two L×T surfaces and two W×T surfaces of the above intermediate blank, and the application amount of Tb element on each of the above surfaces of any matrix is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After that, the two L×T surfaces and two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0194] Curing treatment:

[0195] The insulating adhesive paste is applied between the W×T surfaces of any two adjacent above-mentioned matrices to form an intermediate body, and then the insulating adhesive paste is applied between the L×T surfaces of any eight adjacent intermediate bodies and then cured. After the curing treatment is completed, the temperature is lowered to room temperature to form a bonded magnet with two segments bonded in the length direction and eight segments bonded in the width direction. Then, the bonded magnet is cut perpendicular to the orientation direction to form a 16-segment bonded magnet assembly with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0196] Other conditions are the same as those in Example 1.

[0197] Example 5

[0198] In step S6 of Example 5, an intermediate blank with dimensions of L = 10.1 mm, W = 32.00 mm, and T = 37.5 mm is cut;

[0199] Grain boundary diffusion treatment:

[0200] The above intermediate blank is subjected to grain boundary diffusion treatment, specifically: Tb element is coated on two W×T surfaces of the above intermediate blank, and the application amount of Tb element on each of the above surfaces of any matrix is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After that, the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0201] Curing treatment:

[0202] The insulating adhesive paste is applied between the W×T surfaces of any four adjacent above-mentioned matrices and then cured. After the curing treatment is completed, the temperature is lowered to room temperature to form four segments bonded in the length direction, and then the bonded magnet is cut perpendicular to the orientation direction to form a 4-segment bonded magnet assembly with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0203] Other conditions are the same as those in Example 1.

[0204] Example 6

[0205] In step S6 of Example 6, an intermediate blank with dimensions of L = 10.1 mm, W = 16.10 mm, and T = 37.5 mm is cut and formed;

[0206] Grain boundary diffusion treatment:

[0207] The above intermediate blank is subjected to grain boundary diffusion treatment. Specifically, Tb element is coated on both L×T surfaces and both W×T surfaces of the above intermediate blank. The application amount of Tb element on each of the above surfaces of any matrix is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0208] Curing treatment:

[0209] Insulating adhesive paste is applied between the W×T surfaces of any adjacent 4 of the above matrices to form an intermediate body, and then insulating adhesive paste is applied between the L×T surfaces of any adjacent 2 intermediate bodies and then cured. After the curing treatment is completed and cooled to room temperature, a bonded magnet with 4 segments bonded in the length direction and 2 segments bonded in the width direction is formed. Then, the bonded magnet is cut perpendicular to the orientation direction to form an 8-segment bonded magnet assembly with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0210] Other conditions are the same as those in Example 1.

[0211] Example 7

[0212] In step S6 of Example 7, an intermediate blank with dimensions of L = 10.1 mm, W = 8.10 mm, and T = 37.5 mm is cut and formed;

[0213] Grain boundary diffusion treatment:

[0214] The above intermediate blank is subjected to grain boundary diffusion treatment. Specifically, Tb element is coated on both L×T surfaces and both W×T surfaces of the above intermediate blank. The application amount of Tb element on each of the above surfaces of any matrix is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0215] Curing treatment:

[0216] After applying the insulating adhesive paste between the W×T surfaces of any four adjacent substrates above, an intermediate body is formed. Then, the insulating adhesive paste is applied between the L×T surfaces of any four adjacent intermediate bodies and then cured. After the curing process is completed, the temperature is reduced to room temperature to form a bonded magnet with four segments of bonding in the length direction and four segments of bonding in the width direction. Then, the bonded magnet is cut along a direction perpendicular to the orientation direction to form a 16-segment bonded magnet assembly with dimensions of L = 40.0 mm, W = 32 mm, and T = 2.5 mm.

[0217] Other conditions are the same as in Example 1.

[0218] Example 8

[0219] In step S6 of Example 8, an intermediate blank with dimensions of L = 10.1 mm, W = 4.1 mm, and T = 37.5 mm is cut.

[0220] Grain boundary diffusion treatment:

[0221] The above intermediate blank is subjected to grain boundary diffusion treatment, specifically: Tb element is coated on the two L×T surfaces and the two W×T surfaces of the above intermediate blank. The application amount of Tb element on each of the above surfaces of any one substrate is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0222] Curing treatment:

[0223] After applying the insulating adhesive paste between the W×T surfaces of any four adjacent substrates above, an intermediate body is formed. Then, the insulating adhesive paste is applied between the L×T surfaces of any eight adjacent intermediate bodies and then cured. After the curing process is completed, the temperature is reduced to room temperature to form a bonded magnet with four segments of bonding in the length direction and eight segments of bonding in the width direction. Then, the bonded magnet is cut along a direction perpendicular to the orientation direction to form a 32-segment bonded magnet assembly with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0224] Other conditions are the same as in Example 1.

[0225] Example 9

[0226] In step S6 of Example 9, an intermediate blank with dimensions of L = 5.1 mm, W = 32.0 mm, and T = 37.5 mm is cut.

[0227] Grain boundary diffusion treatment:

[0228] The above intermediate blank is subjected to grain boundary diffusion treatment, specifically: Tb single element is coated on both W×T surfaces of the above intermediate blank, and the application amount of Tb single element on each surface of any matrix is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0229] Curing treatment:

[0230] The insulating adhesive paste is applied between the W×T surfaces of any adjacent 8 of the above matrices and then cured. After the curing treatment is completed, it is cooled to room temperature. Then, the bonded magnet is cut along the direction perpendicular to the orientation direction to form 32 segments of bonded magnet assemblies with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0231] Other conditions are the same as those in Example 1.

[0232] Example 10

[0233] In step S6 of Example 10, an intermediate blank with dimensions of L = 5.1 mm, W = 16.1 mm, and T = 37.5 mm is cut.

[0234] Grain boundary diffusion treatment:

[0235] The above intermediate blank is subjected to grain boundary diffusion treatment, specifically: Tb single element is coated on both L×T surfaces and both W×T surfaces of the above intermediate blank, and the application amount of Tb single element on each surface of any matrix is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0236] Curing treatment:

[0237] The insulating adhesive paste is applied between the W×T surfaces of any adjacent 8 of the above matrices to form an intermediate body, and then the insulating adhesive paste is applied between the L×T surfaces of any adjacent 2 intermediate bodies and then cured. After the curing treatment is completed, it is cooled to room temperature to form a bonded magnet with 8 segments bonded in the length direction and 2 segments bonded in the width direction. Then, the bonded magnet is cut along the direction perpendicular to the orientation direction to form 16 segments of bonded magnet assemblies with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0238] Other conditions are the same as those in Example 1.

[0239] Example 11

[0240] In step S6 of Example 11, an intermediate blank with dimensions of L = 5.1 mm, W = 8.1 mm, and T = 37.5 mm is cut and formed;

[0241] Grain boundary diffusion treatment:

[0242] The above intermediate blank is subjected to grain boundary diffusion treatment. Specifically: Tb element is coated on both L×T surfaces and both W×T surfaces of the above intermediate blank. The application amount of Tb element on each of the above surfaces of any substrate is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0243] Curing treatment:

[0244] Insulating adhesive paste is applied between the W×T surfaces of any adjacent 8 of the above substrates to form an intermediate body, and then insulating adhesive paste is applied between the L×T surfaces of any adjacent 4 intermediate bodies and then cured. After the curing treatment is completed and cooled to room temperature, an adhesive magnet with 8 segments of bonding in the length direction and 4 segments of bonding in the width direction is formed. Then, the adhesive magnet is cut perpendicular to the orientation direction to form a 32-segment adhesive magnet assembly with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0245] Other conditions are the same as in Example 1.

[0246] Example 12

[0247] In step S6 of Example 12, an intermediate blank with dimensions of L = 5.1 mm, W = 4.1 mm, and T = 37.5 mm is cut and formed;

[0248] Grain boundary diffusion treatment:

[0249] The above intermediate blank is subjected to grain boundary diffusion treatment. Specifically: Tb element is coated on both L×T surfaces and both W×T surfaces of the above intermediate blank. The application amount of Tb element on each of the above surfaces of any substrate is 0.6%. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h. After completion, the two L×T surfaces and the two W×T surfaces of the intermediate blank after grain boundary diffusion treatment are ground using a diamond grinding wheel.

[0250] Curing treatment:

[0251] Apply the insulating adhesive paste between the W×T surfaces of any adjacent 8 of the above substrates to form an intermediate body. Then, apply the insulating adhesive paste between the L×T surfaces of any adjacent 4 intermediate bodies and perform a curing treatment. After the curing treatment is completed, cool down to room temperature to form a bonded magnet with 8 segments of bonding in the length direction and 8 segments of bonding in the width direction. Then, cut the bonded magnet perpendicular to the orientation direction to form a 64-segment bonded magnet assembly with dimensions of L = 40.0 mm, W = 32.0 mm, and T = 2.5 mm.

[0252] Other conditions are the same as in Example 1.

[0253] Comparative Example 1

[0254] The preparation conditions of the intermediate blank in Comparative Example 1 are the same as in Example 1.

[0255] Grain boundary diffusion treatment:

[0256] Perform grain boundary diffusion treatment on the above intermediate blank. Specifically: Coat the two L×W surfaces of the above intermediate blank with Tb elemental substance, and the heavy rare earth contents coated on different regions of the two L×W surfaces are inconsistent. Perform heat treatment at 900 °C for 20 h, and then perform tempering treatment at 500 °C for 5 h to form the same coercivity distribution as in Example 2. After completion, use a diamond grinding wheel to grind the two L×T surfaces of the intermediate blank after grain boundary diffusion treatment.

[0257] Surface degreasing:

[0258] Perform phosphating treatment and degreasing on the intermediate blank after the above grain boundary diffusion treatment in sequence to obtain a substrate without rust and grease on the surface; the phosphating solution used for phosphating treatment is a composite phosphating solution, and the degreasing solution used for degreasing is a degreasing powder with a mass content of 2%.

[0259] Spray epoxy resin:

[0260] Spray epoxy resin on the six surfaces of the above substrate to form a 30-μm coating on each of the six surfaces as the final magnet assembly.

[0261] Comparative Example 2

[0262] In Comparative Example 2, a magnet with an integrally formed double-sided comb shape (the middle is a connected substrate, and the two sides are tooth-shaped substrates with pores in the middle) is used, and there is no bonding layer in the middle of the magnet; then, perform surface treatment on all surfaces of the magnet by spraying epoxy resin to form a 30-μm coating on all surfaces as the final magnet assembly.

[0263] Comparative Example 3

[0264] The preparation conditions of the intermediate blank in Comparative Example 3 are the same as in Example 1.

[0265] Grain boundary diffusion treatment:

[0266] The above intermediate blank is subjected to grain boundary diffusion treatment, specifically: coating the two L×W surfaces of the above intermediate blank with Tb element, the application amount of Tb element on each surface of any matrix is 0.6%, and the heavy rare earth content coated in different regions of the two L×W surfaces is the same. Heat treatment is carried out at 900 °C for 20 h, and then tempering treatment is carried out at 500 °C for 5 h to make the coercivity equal at each part on any plane parallel to the L×W surface.

[0267] Surface degreasing:

[0268] The intermediate blank after the above grain boundary diffusion treatment is successively subjected to phosphating treatment and degreasing to obtain a matrix without rust and grease on the surface; the phosphating solution used for phosphating treatment is a composite phosphating solution, and the degreasing solution used for degreasing is a degreasing powder with a mass content of 2%.

[0269] Spraying epoxy resin:

[0270] Epoxy resin is sprayed on the six surfaces of the above matrix to form a 30-μm coating on each of the six surfaces as the final magnet assembly.

[0271] Effect Example 1

[0272] The following tests are carried out on Examples 1-12 and Comparative Examples 1-3:

[0273] 1. Test of surface coercivity and internal coercivity of the matrix: The surface coercivity and internal coercivity of the matrix are measured by using the PBH-1000 pulsed magnetic property measuring device of NDK Company, Japan. Among them, for the coercivity at different positions, small-size matrices (1 mm×1 mm×1 mm) are first cut from different positions and then measured separately to obtain the surface coercivity and internal coercivity respectively.

[0274] Among them, the coercivity distribution diagram along the length direction of the bonded magnet assembly in Example 9 is as Figure 2 shown, the coercivity distribution diagram along the length direction of the bonded magnet assembly in Comparative Example 1 is as Figure 3 shown, and the coercivity distribution diagram along the length direction of the bonded magnet assembly in Comparative Example 3 is as Figure 4 shown; where L in the figure is the length of the bonded magnet assembly and W is the width of the bonded magnet assembly.

[0275] 2. Magnetic flux test: The magnetic flux of the bonded magnet assembly is tested by using an FM-1 magnetic flux meter and a D300 coil.

[0276] The above test results are listed in Table 2 below:

[0277] Table 2

[0278]

[0279] Effect Example 2

[0280] The following tests were conducted on Examples 1-12:

[0281] 1. Adhesive joint width t and its standard deviation: The adhesive joint width of the bonded magnet assemblies prepared in Examples 1-12 was measured using an optical microscope, and the standard deviation σt of each adhesive joint width was calculated according to the standard deviation calculation formula.

[0282] 2. Resistance at both ends of the adhesive layer: Tested using a multimeter.

[0283] 3. Volume resistivity of the adhesive layer: Tested in accordance with the national standard "GB / T 1410".

[0284] The above test results are listed in Table 3 below:

[0285] Table 3

[0286]

[0287] Since there is no adhesive layer in Comparative Examples 1-3, there are no effect data related to the adhesive layer. As can be seen from the above table, the resistance at both ends of the adhesive layer of the bonded magnets in the examples of the present invention > 20 MΩ, and the volume resistivity is as high as 1.1×10 15 , and this adhesive layer can effectively disconnect the flow path of eddy currents, reduce the eddy current heating of high-torque and high-speed permanent magnet motors, and improve the heat resistance of the magnets.

[0288] Effect Example 3

[0289] The following tests were conducted on Examples 1-12 and Comparative Examples 1-3:

[0290] 1. Initial demagnetization temperature test: The bonded magnet assembly was installed in the rotor of a 6-pole IPM rotating machine. The rotor had an outer diameter of 150 mm and a length of 90 mm. The rotor of this structure was magnetized and then assembled in the stator to form an IPM motor, which was placed in an oven for heating while the motor was running. The temperature when the induced electromotive force decreased by ≥ 1% was recorded as the initial demagnetization temperature.

[0291] Among them, the higher the initial demagnetization temperature, the better the tolerance of the bonded magnet assembly.

[0292] 2. Iron loss test: The bonded magnet assembly was installed in the rotor of a 6-pole IPM rotating machine. The rotor had an outer diameter of 150 mm and a length of 90 mm. The rotor of this structure was magnetized and then assembled in the stator to form an IPM motor.

[0293] The no-load test method was used: No-load operation: When the motor was unloaded, the input power P0 was used to overcome the stator copper loss Pcu1 , iron loss \(P\) Fe and mechanical loss \(P\) mec , that is, \(P_0 = P\) cu1 + \(P\) Fe + \(P\) mec ;

[0294] Separation of iron loss and mechanical loss: By changing the voltage, plot the curve of \(P\) Fe + \(P\) mec versus the square of the voltage. Extend the straight-line segment to intersect the vertical axis. The intercept is the mechanical loss, and the slope corresponds to the iron loss. The calculation formula is: \(P\) Fe = \(P\) m - \(P\) out − \(P\) cu − \(P\) mec − \(P\) stray , where \(P\) m is the input power, \(P\) out is the output power, \(P\) cu is the copper loss, \(P\) stray is the stray loss, usually estimated at 0.5% - 1.5% of the rated power. In this invention, \(P\) stray is taken as 1%.

[0295] The above test results are listed in Table 4:

[0296] Table 4

[0297]

[0298] The bonded magnet of the present invention can achieve an iron loss lower than 172.3 W and a starting demagnetization temperature higher than 162 °C, indicating that the bonded magnet of the present invention has excellent anti-eddy current loss effect and heat resistance effect.

[0299] Compared with Comparative Example 1, in Comparative Example 1, no insulating adhesive and microbeads are used to form the bonding layer, resulting in an increase in its iron loss, a decrease in the starting demagnetization temperature, and poor heat resistance. Compared with Comparative Example 1, in Example 2, the iron loss decreases by 51.6 W, the starting demagnetization temperature increases by 8 °C, and both the anti-eddy current loss effect and the heat resistance effect become better.

[0300] Comparative Example 2 is integrally formed without forming a bonding layer, and electrical conduction can still be achieved between the interconnected substrates. Therefore, the iron loss is 44 W higher than that of Example 9, the starting demagnetization temperature is 6 °C lower, and the heat resistance is reduced.

[0301] In Comparative Example 3, the coercivity of the surface layers adjacent to and opposite to the bonding layer in the substrate is equal to that of the interior of the substrate and is relatively low. At the same time, in Comparative Example 3, no insulating adhesive and microbeads are used to form the bonding layer, resulting in an increase in its iron loss, a decrease in the starting demagnetization temperature, and a reduction in heat resistance.

Claims

1. An adhesive magnet, characterized in that, It includes at least two substrates; an adhesive layer is provided between any two adjacent substrates; The adhesive layer includes an insulating adhesive and microbeads; the D50 particle size of the microbeads is more than 10 μm and less than 90 μm; The coercivity of the surface layer of the substrate is higher than that of the interior of the substrate; wherein, the surface layer of the substrate is the surface layer adjacent to the adhesive layer and / or the surface layer opposite to the adhesive layer.

2. The bonded magnet according to claim 1, wherein The material of the microbeads includes ceramic materials and / or glass materials; Among them, preferably, the ceramic materials include one or more of metal oxides, carbides, nitrides and borides; Among them, the metal oxides include, for example, alumina and / or zirconia; Among them, the carbides include, for example, silicon carbide and / or boron carbide; Among them, the nitrides include, for example, silicon nitride and / or aluminum nitride; Among them, the borides include, for example, zirconium boride and / or silicon boride; Among them, preferably, the glass materials include one or more of Na2SiO3, CaSiO3, SiO2, Na2O·CaO·6SiO2, K2O, CaO and B2O3; And / or, the material of the microbeads is a ceramic material, and the density of the microbeads is less than 1.5 g / cm 3 , for example, 1.2 g / cm 3 ; and / or, the material of the microbeads is a glass material, and the density of the microbeads is greater than 2.5 g / cm 3 , for example, 1.2 g / cm 3 ; And / or, the roundness of the microbeads is 0.4 - 1, for example, 0.

6.

3. The bonded magnet according to claim 1, wherein, The difference between the coercivity of the two surfaces of the substrate adjacent to or opposite to the adhesive layer and the coercivity of the interior of the substrate is ≥ 0.5 kOe; And / or, the coercivity of the two surfaces of the substrate adjacent to or opposite to the adhesive layer is ≥ 18.5 kOe, for example, 25.02 kOe, 25.03 kOe, 25.05 kOe, 25.07 kOe, 25.08 kOe, 25.09 kOe, 25.1 kOe, 25.11 kOe, 25.12 kOe or 25.19 kOe; And / or, the coercivity of the interior of the substrate is ≥ 18 kOe, for example, 23.02 kOe, 23.04 kOe, 23.05 kOe, 23.08 kOe, 23.09 kOe, 23.12 kOe, 23.15 kOe, 23.16 kOe, 23.17 kOe or 23.53 kOe; And / or, in any one of the adhesive layers, the mass percentage of the microbeads in the adhesive layer is 0.1% - 5%, for example, 1%; And / or, in any one of the adhesive layers, the mass percentage of the insulating adhesive in the adhesive layer is 95% - 99.9%, for example, 99%; And / or, the mass percentage of the adhesive layer in the substrate is less than 2% and not zero, for example, 0.12%; 4. The bonded magnet according to claim 1, wherein, The thickness of each of the adhesive layers is independently 20 - 100 μm; And / or, the bonded magnet includes at least three substrates and adhesive layers respectively provided between two adjacent substrates; Among them, preferably, the standard deviation σt of the seam width t of different adhesive layers is < 10, and σt is, for example, 3.1, 3.2, 3.3, 3.4, 3.5, 3.7 or 4.1; Among them, preferably, in any one of the adhesive layers, the seam width t is 1 - 3 times the D50 particle size of the microbeads; Preferably, in any of the bonding layers, the width t of the glue seam is 20 - 100 μm, for example, 50 - 90 μm; and / or, the resistance at both ends of the bonding layer is ≥0.1 MΩ, for example, >20 MΩ; and / or, the bonded magnet includes 3 - 100 substrates.

5. A method for preparing an adhesive magnet, characterized in that, It includes the following steps: Applying an insulating bonding paste between any two adjacent substrates and then performing a curing treatment to form a bonding layer between the two adjacent substrates; The coercivity of two surfaces of the substrate adjacent to or opposite to the bonding layer is higher than the coercivity inside the substrate; Wherein, the insulating bonding paste includes an insulating binder and microbeads; the D50 particle size of the microbeads is more than 10 μm and less than 90 μm; Wherein, the pressure of the curing treatment is 0.5 - 2.5 Mpa.

6. The method for preparing the bonded magnet according to claim 5, characterized in that, The substrate is a neodymium iron boron magnet; and / or, the number of the substrates is 2 - 100, more preferably 3 - 100; and / or, the difference between the coercivity of two surfaces of the substrate adjacent to or opposite to the bonding layer and the coercivity inside the substrate is ≥0.5 kOe; and / or, the coercivity of two surfaces of the substrate adjacent to or opposite to the bonding layer is ≥18.5 kOe, for example, 25.02 kOe, 25.03 kOe, 25.05 kOe, 25.07 kOe, 25.08 kOe, 25.09 kOe, 25.1 kOe, 25.11 kOe, 25.12 kOe or 25.19 kOe; and / or, the coercivity inside the substrate is ≥18 kOe, for example, 23.02 kOe, 23.04 kOe, 23.05 kOe, 23.08 kOe, 23.09 kOe, 23.12 kOe, 23.15 kOe, 23.16 kOe, 23.17 kOe or 23.53 kOe.

7. The preparation method of the bonded magnet according to claim 5, characterized in that, The preparation method of the substrate includes the following steps: applying a diffusion source to two opposite surfaces of an intermediate blank, and then performing a heat treatment and a tempering treatment in sequence to obtain the substrate; Wherein, preferably, the method of applying the diffusion source includes sputtering, evaporation coating, coating, printing or electrodeposition; Wherein, preferably, the diffusion source includes one or more of heavy rare earth elements, alloys containing heavy rare earth elements, hydrides containing heavy rare earth elements, fluorides containing heavy rare earth elements and oxides containing heavy rare earth elements; wherein, the heavy rare earth is, for example, Dy and / or Tb; Wherein, preferably, the temperature of the heat treatment is 710 - 1000 °C, for example, 900 °C; Wherein, preferably, the time of the heat treatment is 5 - 50 h, for example, 20 h; Wherein, preferably, the temperature of the tempering treatment is 400 - 600 °C, for example, 500 °C; Wherein, preferably, the time of the tempering treatment is 2 - 8 h, more preferably 3 - 6 h, for example, 5 h; Wherein, preferably, the application amount of the diffusion source is 0.5% - 1%, for example, 0.6%; and / or, the temperature of the curing treatment is 100 - 250 °C; And / or, the curing treatment includes a first heating stage and a second heating stage, the temperature of the first heating stage is 100 - 250 °C, and the temperature of the second heating stage is higher than that of the first heating stage; Among them, preferably, the pressure of the first heating stage is 0.5 - 2.5 Mpa, for example, 2 Mpa; Among them, preferably, the time of the first heating stage is 0.1 - 6 h, for example, 1 h; Among them, preferably, the temperature of the first heating stage is 120 °C; Among them, preferably, the temperature of the second heating stage is 150 - 250 °C, for example, 160 °C; Among them, preferably, the pressure of the second heating stage is 0.5 - 2.5 Mpa, for example, 2 Mpa; Among them, preferably, the time of the second heating stage is 0.1 - 6 h, for example, 1 h.

8. The method for preparing the bonded magnet according to claim 5, characterized in that, The material of the microbeads includes ceramic material and / or glass material; Among them, preferably, the ceramic material includes one or more of metal oxides, carbides, nitrides and borides; Among them, the metal oxide includes, for example, alumina and / or zirconia; Among them, the carbide includes, for example, silicon carbide and / or boron carbide; Among them, the nitride includes, for example, silicon nitride and / or aluminum nitride; Among them, the boride includes, for example, zirconium boride and / or silicon boride; Among them, preferably, the glass material includes one or more of Na2SiO3, CaSiO3, SiO2, Na2O·CaO·6SiO2, K2O, CaO and B2O3; And / or, the D50 particle size of the microbeads is 20 - 40 μm or 50 - 70 μm; And / or, the material of the microbeads is a ceramic material, and the density of the microbeads is less than 1.5 g / cm 3 , for example, 1.2 g / cm 3 ; And / or, the material of the microbeads is glass material, and the density of the microbeads is greater than 2.5 g / cm 3 , for example, 1.2 g / cm 3 ; And / or, the roundness of the microbeads is 0.4 - 1, for example, 0.6; And / or, the types of the insulating adhesive include one or more of epoxy resin, cyanoacrylate, unsaturated polyester resin, phenolic resin and polyimide resin; And / or, the mass percentage of the microbeads in the insulating adhesive paste is 0.1% - 5%, for example, 1%; And / or, the mass percentage of the insulating adhesive in the insulating adhesive paste is 95% - 99.9%, for example, 99%; And / or, the mass percentage of the insulating adhesive paste in the matrix is less than 2%, for example, 0.12%.

9. A bonded magnet prepared by the method for preparing a bonded magnet according to any one of claims 5 - 8.

10. An application of a bonded magnet according to any one of claims 1 - 4 and 9 in an electric motor.

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