Segmented magnet based on glass fiber reinforcement, and preparation method and application thereof

Abstract

The invention discloses a segmented magnet based on glass fiber reinforcement and a preparation method and application thereof, and the segmented magnet comprises: (K1) a plurality of magnetic steels which are arranged at intervals; (K2) a plurality of bonding layers, any two adjacent magnetic steels are connected through the bonding layer, and at least one part of the bonding layer is prepared by using a bonding material; the bonding material comprises a glass fiber layer modified by a silane coupling agent and adhesive layers arranged on two opposite surfaces of the glass fiber layer. After the segmented magnets are bonded by the bonding material, crack propagation of the magnets is inhibited through a fiber network of the bonding material, and the service life of the magnet assembly is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth permanent magnet material bonding, and in particular to a glass fiber reinforced segmented magnet, and a preparation method and application thereof. Background Art

[0002] In high-speed motors, traditional sintered NdFeB magnets are prone to eddy current losses, resulting in reduced efficiency and increased temperature rise. The industry is gradually adopting segmented magnets to reduce eddy current losses. Segmented magnets, with their high magnetic properties, reduced eddy current losses, improved efficiency, good mechanical strength, high corrosion resistance, and stable process, have driven technological advancement and application expansion in the NdFeB industry.

[0003] The traditional preparation process of segmented magnets is: overall sintering → cutting into blocks → surface treatment → segmented assembly → secondary cutting → secondary surface treatment. Among them, the traditional segmented assembly method is glue bonding, which usually uses epoxy resin-based glue and adds glass beads as fillers. The segmented assembly is completed through the steps of gluing, extrusion tooling, and high-temperature curing and molding. The glue bonding assembly method can achieve simple process and low cost, and is suitable for general magnetic components and small and medium-sized batch production. However, the traditional glue bonding method has shortcomings such as low mechanical properties, stress concentration, poor temperature resistance, process limitations, excessive glue overflow, and poor consistency of glue seam thickness.

[0004] In the prior art, a series of methods have been used to overcome the shortcomings of traditional glue bonding methods. For example, patent CN101763929A discloses a method for insulating neodymium iron boron permanent magnet components. This method uses a mixture of glass beads and epoxy resin, and uses a dedicated fixture and a segmented curing process to control the thickness of the glue seam and insulation. However, the glass beads only control the thickness and have limited strength. They are only mixed with fillers without chemical modification, and the temperature resistance is ≤150°C (the glass bead / microbead interface is prone to failure). In addition, the glass bead-mixed glue is prone to bubbles, resulting in uneven insulation.

[0005] Patent CN109253903A discloses a composite bonding process with controllable bond thickness. Hollow glass beads or chopped copper wire are added to precisely control the adhesive layer thickness, and segmented pressurization optimizes strength. However, glass beads only control thickness, resulting in limited strength. Furthermore, they are simply mixed with fillers without chemical modification, and have a temperature resistance of ≤150°C (the glass bead / bead interface is susceptible to failure). Hollow glass beads and chopped copper wire require precision machining, which is costly.

[0006] Patent CN109686530A discloses a sheet adhesive material and magnetic workpiece, as well as a preparation method and uses thereof. The material uses an insulating layer of glass fiber fabric sandwiched between two adhesive layers to form a double-sided adhesive structure. This structure improves insulation and adhesive seam uniformity through segmented pressurization and curing. However, the material does not undergo special fiber treatment and relies solely on the double-sided adhesive structure. The sheet material has a thickness of 0.06 to 0.20 mm.

[0007] Patent CN118755391A discloses a novel, high-performance bonding method that incorporates collagen fiber membranes as solvent evaporation channels, accelerating curing and forming mechanical interlocks, thereby enhancing shear strength. While collagen fiber membranes rely on physical interlocking, rather than chemical bonding, to enhance bonding strength, they suffer from insufficient temperature resistance and high cost. Summary of the Invention

[0008] To improve the above technical problems, the present invention provides an adhesive material for bonding NdFeB magnets, which comprises a glass fiber layer modified with a silane coupling agent and adhesive layers arranged on two opposite surfaces of the glass fiber layer.

[0009] According to an embodiment of the present invention, the glass fiber layer modified with a silane coupling agent is prepared by immersing a glass fiber substrate in a silane solution.

[0010] According to an embodiment of the present invention, the silane solution comprises, based on 100% by mass, 1-2 wt% of a silane coupling agent, 0.1-0.5 wt% of a surfactant, 0.5-1 wt% of a crosslinking agent, 0.1-0.3 wt% of an antioxidant, and the rest being a solvent.

[0011] According to an embodiment of the present invention, the silane coupling agent may be at least one of γ-aminopropyltriethoxysilane (KH-550), γ-glycidoxypropyltrimethoxysilane (KH-560), and γ-methacryloxypropyltrimethoxysilane (KH-570).

[0012] According to an embodiment of the present invention, the solvent may be at least one of water (eg, deionized water), ethanol, and isopropyl alcohol.

[0013] According to an embodiment of the present invention, the surfactant may be at least one of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate.

[0014] According to an embodiment of the present invention, the cross-linking agent may be at least one of titanate and aluminate.

[0015] According to an embodiment of the present invention, the antioxidant may be at least one of 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-1,4-benzenediol, α-tocopherol, and 3,5-di-tert-butyl-4-hydroxyphenylpropionate;

[0016] According to an embodiment of the present invention, the glass fiber matrix serves as a reinforcing filler, and the length of the glass fiber matrix is ​​400 to 1200 μm and the diameter is 10 to 15 μm; preferably, the aspect ratio of the glass fiber matrix is ​​30 to 100, preferably 40 to 80, for example 40, 50, 60, 70 or 80.

[0017] According to an embodiment of the present invention, the content of the glass fiber matrix is ​​2-10 wt %, preferably 2-5 wt %, for example 2 wt %, 3 wt %, 4 wt % or 5 wt % of the total mass of the adhesive material.

[0018] According to an embodiment of the present invention, the glue used in the glue layer is epoxy resin glue.

[0019] The present invention also provides a method for preparing the adhesive material, the method comprising:

[0020] (S1) preparing a glass fiber layer modified with a silane coupling agent;

[0021] (S2) applying glue on two opposite surfaces of the glass fiber layer to form a glue layer.

[0022] According to an embodiment of the present invention, the preparation method of the glass fiber layer modified with a silane coupling agent in step (S1) is:

[0023] (1) preparing or preparing a glass fiber matrix: for example, preparing a glass fiber matrix by a weaving or non-woven process;

[0024] (2) Pre-treating the glass fiber substrate: immersing the glass fiber substrate in a silane solution and heating the solution to react, thereby preparing a glass fiber layer modified with a silane coupling agent.

[0025] Preferably, the temperature of the heating reaction is 80-120° C., and the heating reaction time is 30-60 min.

[0026] Preferably, step (2) further comprises removing water from the reaction product (if water is used as the solvent of the silane solution).

[0027] In the present invention, after the glass fiber is treated with a silane solution, a uniform silane film is formed on the surface of the glass fiber matrix, thereby enhancing the interface bonding with the epoxy resin glue.

[0028] According to an embodiment of the present invention, in step (S2), glue is evenly applied to both sides of the glass fiber layer, and pressure is applied to prepare the bonding material.

[0029] Preferably, the applied pressure is 0.1-0.5 MPa, for example, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa or 0.5 MPa.

[0030] In the present invention, a silane coupling agent is first dissolved in a solvent, the pH is adjusted to 4-5 with acetic acid, and then a surfactant, a cross-linking agent, and an antioxidant are added and stirred to form a silane solution. The glass fiber is immersed in the silane solution for 5-10 minutes to ensure complete wetting of the fiber and to avoid the formation of bubbles. The fiber is then dried at 80-120°C for 30-60 minutes to remove moisture and complete the condensation reaction, thereby preparing a glass fiber layer.

[0031] The present invention adjusts the thickness of the adhesive material and the extrusion pressure (i.e., 0.1-0.5 MPa) to precisely control the adhesive seam within a range of 35-55 μm, thereby reducing the amount of adhesive material used by 20-30%.

[0032] The present invention also provides an application of the bonding material in bonding neodymium iron boron magnets.

[0033] The present invention also provides a segmented magnet, comprising:

[0034] (K1) a plurality of magnetic steels, wherein the plurality of magnetic steels are arranged at intervals;

[0035] (K2) A plurality of adhesive layers, wherein any two adjacent magnetic steels are connected via the adhesive layer, wherein at least a portion of the adhesive layer is prepared using the above-mentioned adhesive material.

[0036] In the present invention, "plurality" means two or more, for example, 2-100, preferably 2-50, more preferably 2-30.

[0037] According to an embodiment of the present invention, the method further comprises performing surface treatment on the magnetic steel, for example, performing degreasing and passivation treatments on the magnetic steel to ensure that the surface of the magnetic steel is free of rust and grease.

[0038] According to an embodiment of the present invention, step (K2) specifically comprises: bonding any two adjacent magnetic steels with the bonding material, applying pressure, and heating and curing to obtain the segmented magnet.

[0039] Preferably, the applied pressure is 0.5-1 MPa, for example, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa or 1 MPa.

[0040] Preferably, the curing temperature is 20-250°C. For example, the curing process can be divided into two stages: first curing at 20-150°C (preferably 60-120°C), and then curing at 150-250°C (preferably 160-220°C). The curing time is 0.1-36 hours, for example, first curing at 20-150°C for 0.1-24 hours, and then curing at 150-250°C for 0.1-12 hours, to ensure that the insulating layer is completely cured.

[0041] Preferably, the method further comprises step (K3): performing secondary cutting and / or secondary surface treatment on the prepared product to obtain the segmented magnet.

[0042] Preferably, the secondary cutting is secondary mechanical cutting commonly used in the art, such as cutting, multi-wire cutting, etc.

[0043] Preferably, the secondary surface treatment is at least one of phosphating, spraying, powder spraying, etc. The phosphating, spraying, and powder spraying processes are all known in the art.

[0044] As an exemplary embodiment of the present invention, the preparation method of the segmented magnet is:

[0045] a) Surface treatment: Degreasing and passivation of magnetic steel,

[0046] b) Segment assembly:

[0047] Place the adhesive material on the bonding surface of the magnetic steel, cut it quantitatively according to the product size, stack 2 to 25 pieces of magnetic steel, fix them with an extrusion tool, apply a pressure of 0.5 to 1 MPa, and initially cure at 20 to 150°C for 0.1 to 24 hours, and then cure at 150 to 250°C for 0.1 to 12 hours;

[0048] c) Secondary cutting: secondary machining of the bonded magnetic steel;

[0049] d) Secondary surface treatment: the magnet after secondary cutting is subjected to protective treatments such as phosphating, spraying, and powder spraying to obtain the segmented magnet.

[0050] Beneficial effects of the present invention:

[0051] a) The present invention replaces glass beads with glass fibers. Through the directional reinforcement effect of the fibers, interface optimization, and precise coating methods, it solves the problems of low strength, poor temperature resistance, easy cracking, uneven glue seam thickness, glue overflow, and magnetic flux loss of the adhesive material, and significantly improves the mechanical properties (shear strength ≥ 25 MPa) and temperature resistance (long-term use temperature ≥ 180°C) of the adhesive material. In addition, the glass fiber matrix used is size-controllable and evenly distributed, which can reduce the amount of glue overflow.

[0052] b) After the segmented magnets of the present invention are bonded with an adhesive material, the fiber network of the adhesive material inhibits the expansion of magnet cracks, thereby extending the life of the magnet assembly;

[0053] c) The segmented magnet of the present invention has a simple process and its cost is reduced by more than 40% compared with the carbon fiber solution, and is suitable for large-scale production.

[0054] d) Glue seam consistency: The thickness fluctuation range of the glass fiber layer modified with the silane coupling agent of the present invention is reduced from ±20 μm to ±10 μm, thereby improving insulation properties;

[0055] e) Magnetic flux optimization: The present invention reduces the glue gap of the insulating layer, thereby increasing the effective thickness of the magnetic steel and improving the efficiency of the permanent magnet motor.

[0056] f) The aspect ratio of the glass fiber matrix of the present invention is significantly higher than that of glass beads, forming a three-dimensional network structure in the adhesive layer, which prevents crack propagation through the "bridging effect" and can improve the shear strength and fatigue life by 30-50%.

[0057] g) The present invention uses glass fibers modified with silane coupling agents to form chemical bonds with epoxy resins, reducing interface defects and increasing temperature resistance to 180°C (conventional glue ≤ 150°C). Furthermore, the glass fibers modified with silane coupling agents are evenly dispersed, and the viscosity of the prepared adhesive material is controllable. DETAILED DESCRIPTION

[0058] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0059] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0060] Example 1

[0061] The magnets with sizes of 48.28-4.47-34.47mm are degreased, activated and phosphated to ensure that the surface is free of rust and grease.

[0062] A glass fiber fabric (i.e., a silane-coupling agent-modified glass fiber layer) was prepared by weaving a glass fiber matrix of uniform thickness. The matrix was then immersed in a silane solution for 5 minutes. The silane solution consisted of 1.5 wt% KH-550, 0.3 wt% polyoxyethylene sorbitan monooleate (Tween 80), 0.8 wt% titanate, 0.2 wt% 2-tert-butyl-1,4-diphenol, and the remainder ethanol. The immersed glass fiber was then dried at 100°C for 30 minutes. The glass fiber matrix used had a length of 780 μm, a diameter of 13 μm, and an aspect ratio of 60.

[0063] 0.01g / cm 2 Nippon paint epoxy resin glue is evenly applied to both sides of the fiber fabric and squeezed through a casting roller at a pressure of 0.2MPa to form a bonding material;

[0064] The above adhesive material is continuously conveyed to the bonding surface of the segmented magnet, quantitatively cut according to the product size, and 4 pieces of magnetic steel are stacked and fixed with an extrusion tool, applying a pressure of 0.7Mpa.

[0065] The content of the glass fiber matrix is ​​5wt% of the total mass of the adhesive material.

[0066] The magnetic steel with the adhesive material is cured at 100°C for 1 hour and at 190°C for 3 hours to ensure that the insulating adhesive fiber cloth is completely cured; the bonded magnetic steel is subjected to secondary machining (such as wire cutting, multi-wire cutting, etc.) and spray-coated to obtain segmented magnets.

[0067] Comparative Example 1

[0068] Degrease, activate and phosphate the 48.28-4.47-34.47mm size magnetic steel to ensure that the surface is free of rust and grease;

[0069] Evenly coat the magnet surface with epoxy resin glue (or adhesive material) containing glass beads (the glass bead content is 20wt% of the total mass of the epoxy resin glue containing glass beads). Stack four magnets and secure them with an extrusion tool, applying a pressure of 0.7MPa. Curing is performed at 100°C for 1 hour and at 190°C for 3 hours. Finally, the bonded magnets undergo secondary machining (such as wire cutting, multi-wire cutting, etc.) and are spray-coated.

[0070] The performance parameters of the adhesive material of Example 1 and the epoxy resin glue containing glass beads in Comparative Example 1 are compared as shown in Table 1 below:

[0071] Table 1

[0072]

[0073]

[0074] In Table 1, the glue gap refers to the gap area between adjacent magnet segments filled with adhesive.

[0075] The adhesive seam thickness of the glass fiber-containing adhesive in Example 1 was 35-55 μm, while the adhesive seam thickness of the glass bead-containing adhesive in Comparative Example 1 was 50-80 μm. Because the particle size of glass beads is limited by the production process, screening accuracy, and surface tension, this results in a wide particle size distribution, localized thickness fluctuations in the adhesive seam, and reduced insulation performance. The electrical resistance of Example 1 is higher, the adhesive seam is thinner, the electric field strength is higher, the adhesive layer is denser, and the insulation resistance is generally higher and more uniform, reducing localized leakage.

[0076] The glass fibers in Example 1 are in surface contact, resulting in a large specific surface area, more uniform stress distribution within the adhesive layer, and a stronger bond with the resin interface (chemical bonding + mechanical anchoring). They also offer better temperature resistance, faster heat conduction, and more uniform heat distribution. Thin adhesive seams experience less thermal stress during temperature fluctuations, making them less susceptible to cracking. Furthermore, the glass fibers form a mesh structure that restricts resin flow. Glass beads, on the other hand, are highly fluid and prone to overflow. Comparative Example 1 exhibits high levels of overflow, resulting in wasteful resin.

[0077] Example 1 and Comparative Example 1 were subjected to high-temperature treatments at 190°C and 250°C, respectively. The fiber mesh structure of Example 1 dispersed stress and exhibited superior heat resistance. The methoxy end of the silane coupling agent HK550 reacted with the hydroxyl groups on the glass fiber surface to form a chemical bond, while the amino end reacted with the epoxy groups of the epoxy resin, enhancing interfacial bridging. Shear strength remained unaffected after the 250°C high-temperature treatment. At 250°C, the adhesive material of Comparative Example 1 readily debonded at point contact between the glass beads and the resin, significantly reducing the shear strength at the adhesive seams between the segmented magnets. Compared to Comparative Example 1, Example 1 exhibited higher resistivity, lower adhesive overflow, and significantly improved shear strength.

[0078] Example 2-4 and Comparative Example 2-3

[0079] The preparation method is the same as that of Example 1, except that the content of the glass fiber matrix in the total mass of the adhesive material is shown in Table 2 below:

[0080] Table 2

[0081]

[0082]

[0083] The test method for the standard deviation of the glue seam thickness is as follows: the number of samples in the same batch of experimental examples is 10, the glue seam thickness is tested, and the standard deviation is calculated.

[0084] The glass fiber matrix has a large specific surface area. As the content of the glass fiber matrix increases, the glass fiber network effect is significant, which is beneficial to increasing the viscosity of the adhesive material and reducing the amount of adhesive overflow. However, an excessively high content of the glass fiber matrix will cause uneven adhesive seam thickness. In Comparative Example 3, the excessively high content of the glass fiber matrix agglomerates, resulting in a viscosity of 1200 Pa.s. This viscosity is too high, which is not conducive to the dispersion of the adhesive material and causes large differences in adhesive seam thickness. In Comparative Example 2, the proportion of the glass fiber matrix is ​​too low, and the amount of adhesive overflow is high, resulting in waste.

[0085] Example 5:

[0086] The manufacturing method is the same as that of Example 1, except that the length of the glass fiber matrix is ​​390 μm and the aspect ratio is 30;

[0087] Example 6:

[0088] The manufacturing method is the same as that of Example 1, except that the length of the glass fiber matrix is ​​1170 μm and the aspect ratio is 90.

[0089] Comparative Example 4:

[0090] The manufacturing method is the same as that of Example 1, except that the length of the glass fiber matrix is ​​260 μm and the aspect ratio is 20;

[0091] Comparative Example 5:

[0092] The manufacturing method is the same as that of Example 1, except that the length of the glass fiber matrix is ​​1560 μm and the aspect ratio is 120.

[0093] The specific differences are shown in Table 3 below:

[0094] Table 3

[0095]

[0096]

[0097] As can be seen from the results in Table 3 above, in Comparative Example 4, when the aspect ratio of the glass fiber matrix is ​​less than 30, the fiber network structure does not disperse stress sufficiently, the glue fluidity is too high, and the shear strength at the glue seam of the segmented magnet is too low to meet the requirements of use. In Comparative Example 5, when the aspect ratio of the glass fiber matrix is ​​greater than 100, the fiber continuity and reinforcement effect are more significant, the shear strength is high, but the enhancement effect is limited. At the same time, an excessively high aspect ratio easily leads to fiber agglomeration, resulting in a large difference in glue seam thickness.

[0098] Comparative Example 6:

[0099] The preparation method is the same as that of Example 1, but the glass fiber matrix is ​​not modified with a silane coupling agent.

[0100] Table 4

[0101]

[0102] Salt spray resistance test method: Place the segmented magnet in a neutral salt spray environment and test the shear strength every 24 hours until failure (force value is 20MPa), and record the required time.

[0103] After the glass fiber matrix of Example 1 is pre-treated by silanization, the interfacial bonding strength can be improved by chemical bonding and the three-dimensional network structure can be strengthened. Compared with Comparative Example 6, the shear strength of the segmented magnet is increased by 15%. The formed silane film can block the penetration of moisture and improve the salt spray resistance from 7 days to 30 days.

[0104] The above examples illustrate the embodiments of the present invention. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A bonding material for bonding neodymium iron boron magnets, characterized in that: The invention comprises a glass fiber layer modified by a silane coupling agent and adhesive layers arranged on two opposite surfaces of the glass fiber layer.

2. The adhesive material according to claim 1, characterized in that The glass fiber layer modified with a silane coupling agent is prepared by immersing a glass fiber substrate in a silane solution; Preferably, the silane solution comprises, based on 100% by mass, 1-2 wt% of a silane coupling agent, 0.1-0.5 wt% of a surfactant, 0.5-1 wt% of a cross-linking agent, 0.1-0.3 wt% of an antioxidant, and the remainder being a solvent.

3. The adhesive material according to claim 2, characterized in that The silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; The solvent may be at least one of water, ethanol, and isopropanol; The surfactant is at least one of polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate; The cross-linking agent is at least one of titanate and aluminate; The antioxidant is at least one of 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-1,4-dibenzene, α-tocopherol, and 3,5-di-tert-butyl-4-hydroxyphenylpropionate.

4. The adhesive material according to claim 1, wherein The glass fiber matrix is ​​used as a reinforcing filler, and the aspect ratio of the glass fiber matrix is ​​30 to 100; Preferably, the content of the glass fiber matrix is ​​2-10 wt% of the total mass of the adhesive material. Preferably, the glue used in the glue layer is epoxy resin glue.

5. The method for preparing the adhesive material according to any one of claims 1 to 4, characterized in that: The method comprises: (S1) preparing a glass fiber layer modified with a silane coupling agent; (S2) applying glue on two opposite surfaces of the glass fiber layer to form a glue layer.

6. The method according to claim 5, characterized in that The preparation method of the glass fiber layer modified with a silane coupling agent in step (S1) is as follows: (1) preparing or preparing a glass fiber matrix: for example, preparing a glass fiber matrix by a weaving or non-woven process; (2) Pre-treating the glass fiber substrate: immersing the glass fiber substrate in a silane solution and heating the solution to react, thereby preparing a glass fiber layer modified with a silane coupling agent. Preferably, in step (S2), glue is evenly applied to both sides of the glass fiber layer, and pressure is applied to prepare the bonding material. Preferably, the applied pressure is 0.1-0.5 MPa.

7. Use of the bonding material according to any one of claims 1 to 4 in bonding neodymium iron boron magnets.

8. A segmented magnet comprising: (K1) a plurality of magnetic steels, wherein the plurality of magnetic steels are arranged at intervals; (K2) A plurality of adhesive layers, wherein any two adjacent magnetic steels are connected by the adhesive layer, wherein at least a portion of the adhesive layer is prepared using the adhesive material according to any one of claims 1 to 4.

9. The segmented magnet according to claim 8, characterized in that Step (K2) comprises: bonding any two adjacent magnetic steels with the bonding material, applying pressure, and heating and curing to obtain the segmented magnet.

10. The segmented magnet according to claim 9, characterized in that The applied pressure is 0.5~1Mpa; Preferably, the temperature of heat curing is 20-250° C. For example, the heat curing is divided into two stages: first curing at 20-150° C., and then curing at 150-250° C.; the heat curing time is 0.1-36 hours.

Images