A method for detecting the residual magnetism of permanent magnet ferrite tiles

Abstract

This application provides a method for detecting the residual magnetism of a permanent magnet ferrite tile, comprising the following steps: cleaning the surface of the permanent magnet ferrite tile to be tested; measuring the volume of the tile; uniformly coating a peelable soft magnetic auxiliary layer on the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls of the tile, wherein the relative permeability of the soft magnetic auxiliary layer is 10 to 100 times that of the tile body, and the coating thickness is 0.2-0.6 mm; after the soft magnetic auxiliary layer is naturally dried, subjecting the tile to constant temperature treatment; placing the tile in the center of a magnetizing coil for saturated magnetization, with the magnetization direction consistent with the thickness direction of the tile; peeling off the soft magnetic auxiliary layer after magnetization; measuring the magnetic flux of the tile using the Helmholtz coil method, and calculating the residual magnetism by combining the volume data.

Description

Technical Field

[0001] This invention relates to the field of permanent magnets, and in particular to a method for detecting the residual magnetism of permanent magnet ferrite tiles. Background Technology

[0002] Permanent magnet ferrite tiles are widely used in magnetic devices such as motors and generators, serving as key components for energy conversion and magnetic field control. The remanence (Br) of these tiles is a crucial indicator of their magnetic properties, directly impacting the overall performance and application effectiveness of downstream products. With the continuous development of magnetic materials and device structures, the testing technology for these tiles is receiving increasing attention.

[0003] Currently, commonly used methods for detecting the remanent magnetism of magnetic tiles mainly include standard magnetic property measuring instruments and the Helmholtz coil method. These methods typically require the sample structure to be regular and the end faces to be parallel; otherwise, large measurement errors are likely to occur. CN115825829A measures the magnetic flux through the volume of the sample under test using a Helmholtz coil, then obtains the magnetic flux per unit volume of the sample, and finally calculates the remanence based on the proportional relationship between the magnetic flux per unit volume and the remanence. This method, because the magnetic flux per unit volume is only related to the sample volume, does not require high precision in sample processing during remanence measurement, allowing for rapid sample fabrication and quick and accurate calculation of remanence using the proportional relationship. However, for magnetic tiles with complex structures such as curved surfaces and grooves, localized magnetization unevenness and magnetic flux loss are severe. Under traditional magnetization methods, the magnetic field is unevenly distributed in areas such as curved surfaces and grooves, easily leading to magnetization dead zones, affecting the accuracy and representativeness of the remanence data.

[0004] Therefore, how to effectively improve the magnetization uniformity and data accuracy during remanence measurement without changing the complex structure of the magnetic tile is a key technical problem in this field. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a method for detecting the residual magnetism of a permanent magnet ferrite tile, comprising the following steps: cleaning the surface of the permanent magnet ferrite tile to be tested; measuring the volume of the tile; uniformly coating the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls of the tile with a peelable soft magnetic auxiliary layer, wherein the relative permeability of the soft magnetic auxiliary layer is 10 to 100 times that of the tile body, and the coating thickness is 0.2-0.6 mm; after the soft magnetic auxiliary layer has dried naturally, subjecting the tile to constant temperature treatment; placing the tile in the center of a magnetizing coil for saturated magnetization, with the magnetization direction aligned with the thickness direction of the tile; peeling off the soft magnetic auxiliary layer after magnetization; measuring the magnetic flux of the tile using the Helmholtz coil method, and calculating the residual magnetism by combining the volume data.

[0006] This invention significantly improves the uniformity of magnetic field distribution in complex structural areas by uniformly coating the inner and outer arc surfaces of the magnetic tile, as well as the bottom and sidewalls of the grooves at both ends, with a peelable soft magnetic auxiliary layer whose relative permeability is 10 to 100 times that of the magnetic tile body. During magnetization, the auxiliary layer effectively guides the magnetic flux, eliminating magnetization dead zones and local incomplete magnetization. After magnetization, the auxiliary layer is completely peeled off without affecting the performance of the magnetic tile body. Accurate and reliable test results are ensured by precisely measuring the volume of the magnetic tile, measuring the magnetic flux using the Helmholtz coil method, and calculating the residual magnetic flux using a standard formula. Experimental results verify that the deviation in residual magnetic flux is significantly reduced, making the test results more reliable.

[0007] Furthermore, the soft magnetic auxiliary layer is a ferrite magnetic powder-rubber matrix composite coating, wherein the magnetic powder content in the coating is 40-80 wt%, the rubber matrix content is 15-55 wt%, and the additive content is 1-10 wt%. This formulation combines excellent magnetic permeability and good peeling performance, which can improve the ease of operation and consistency.

[0008] Furthermore, the magnetic powder comprises large-particle magnetic powder and small-particle magnetic powder. The large-particle magnetic powder has a particle size of 70-100 μm, and the small-particle magnetic powder has a particle size of 2-10 μm. The surface of the large-particle magnetic powder is treated with a silane coupling agent. The silane coupling agent forms a chemical bonding layer on the surface of the large particles, enhancing the interfacial bonding strength between the particles and the matrix. The large particles become stress concentration points and peeling initiation points during peeling. The small particles form stable aggregates with the large particles through physical coating and van der Waals forces. During peeling, the large particles drive the surrounding small particles to detach as a whole, thereby significantly reducing the magnetic powder residue on the surface of the magnetic tile after peeling and further improving the detection accuracy.

[0009] Furthermore, the soft magnetic auxiliary layer is applied using an air spray gun with a nozzle diameter of 0.5-1.5 mm. This method ensures a uniform coating, adapts to different structural complexities, and improves magnetization uniformity.

[0010] Furthermore, the soft magnetic auxiliary layer is a peelable rubber magnetic tape or a soluble soft magnetic coating. A peelable rubber magnetic tape refers to a tape that can be completely peeled off by applying external force, while a soluble soft magnetic coating refers to a coating that contains soluble components that can be completely dissolved in a solvent, thereby allowing the coating to be completely removed.

[0011] Furthermore, the volume measurement employs the displacement method. This method is simple, accurate, and suitable for measuring the volume of irregularly shaped magnetic tiles.

[0012] Furthermore, the constant temperature treatment involves immersing the magnetic tile coated with the soft magnetic auxiliary layer in a constant temperature water tank at 15-30 degrees Celsius for 1-10 minutes. This treatment helps stabilize the performance of the auxiliary layer and ensures consistent magnetization.

[0013] Furthermore, the inner diameter of the magnetizing coil is 40-80mm, the number of coil turns is 600-1200, the magnetizing current is 10-30A, and the magnetizing time is 1-10 seconds. This parameter range is suitable for different specifications of magnetic tiles, ensuring sufficient magnetization.

[0014] Furthermore, the magnetic flux measurement adopts the Helmholtz coil method, with an inner diameter of 40-80 mm and a number of 800-1200 turns.

[0015] Furthermore, the formula for converting the remanence Br is Br = (Φ / V) × 1998, where Φ is the average magnetic flux and V is the volume of the magnetic tile. 1998 is an empirical value obtained through multiple experiments, representing the ratio between the sample's remanence Br and the magnetic flux per unit volume. Detailed Implementation

[0016] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0017] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0020] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0021] Unless otherwise specified, the percentage mass fractions mentioned in this application refer to mass percentages for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentages for liquid-phase-liquid mixtures.

[0022] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0023] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0024] The term "particle" as used in this application, or a substance with a defined particle size distribution, is not necessarily spherical in shape; it may be irregular and can be either primary or secondary particles. The particle size of irregular particles is calculated as the average of their maximum and minimum diameters.

[0025] Example 1: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0026] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0027] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (60wt% large-particle magnetic powder with an average particle size of 100μm, 35wt% rubber matrix (polyurethane, Bolino, PU-956), and 5wt% additive Suryfnol 465). Use a 1.0mm nozzle air spray gun to evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The coating thickness should be 0.4mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0028] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0029] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0030] Example 2: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles. The difference from Example 1 is the use of a soluble soft magnetic coating method. Specifically: a soluble soft magnetic coating is prepared: 55wt% ferrite magnetic powder (average particle size 100μm), 40wt% polyvinyl alcohol (PVA) aqueous solution, and 5wt% Suryfnol 465 additive, stirred evenly. The coating is evenly sprayed onto the inner arc surface, outer arc surface, and the bottom and sidewalls of the grooves at both ends using a 1.0mm nozzle air spray gun, with a coating thickness of 0.3mm. After spraying, it is allowed to air dry at room temperature for 10 minutes.

[0031] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0032] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the tile dry with a lint-free cloth. Prepare a soluble soft magnetic coating: 55wt% ferrite magnetic powder, 40wt% polyvinyl alcohol (PVA) aqueous solution, and 5wt% Suryfnol 465 additive. Stir well. Using a 1.0mm nozzle air spray gun, evenly spray the coating onto the inner curved surface, outer curved surface, and the bottom and sidewalls of the grooves at both ends, to a thickness of 0.3mm. Allow to air dry at room temperature for 10 minutes after spraying.

[0033] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0034] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0035] Example 3: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0036] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0037] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (60wt% large-particle magnetic powder with an average particle size of 80μm, 35wt% rubber matrix (polyurethane, Bolino, PU-956), and 5wt% additive Suryfnol 465). Use a 1.0mm nozzle air spray gun to evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The coating thickness should be 0.3mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0038] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0039] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0040] Example 4: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles. The difference from Example 1 is the use of a peelable rubber magnetic tape method. Specifically, a peelable soft magnetic rubber magnetic tape (0.3 mm thick, 10 mm wide) containing 65 wt% ferrite powder (average particle size 100 μm), 35 wt% rubber matrix, and a relative permeability approximately 20 times that of the tile body is selected and cut into strips suitable for each surface. Using tweezers, the tape is tightly adhered sequentially to the inner arc surface, outer arc surface, and the bottom and sidewalls of the grooves at both ends, ensuring no air bubbles, wrinkles, and uniform coverage. After adhesion, the magnetic tile is left to stand at room temperature for 10 minutes to ensure a firm bond.

[0041] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0042] Place the magnetic tile in a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Select a 0.3mm thick, 10mm wide peelable soft magnetic rubber tape (65wt% ferrite powder (average particle size 100μm), 35wt% rubber matrix, with a relative permeability approximately 20 times that of the magnetic tile itself), and cut it into strips suitable for each surface. Use tweezers to firmly adhere the tape to the inner curved surface, outer curved surface, and the bottom and sidewalls of the grooves at both ends, ensuring no air bubbles, wrinkles, or uneven coverage. After adhesion, allow the magnetic tile to stand at room temperature for 10 minutes to ensure a firm bond.

[0043] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0044] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0045] Example 5: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0046] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0047] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (60wt% large-particle magnetic powder with an average particle size of 80μm, 35wt% rubber matrix (polyurethane, Bolino, PU-956), and 5wt% additive Suryfnol 465). Use a 1.0mm nozzle air spray gun to evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The coating thickness should be 0.6mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0048] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0049] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0050] Example 6: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0051] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0052] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading is 37.2mL, and the volume is 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (40wt% large-particle magnetic powder with an average particle size of 80μm, 55wt% rubber matrix (polyurethane, Bolino, PU-956), and 5wt% additive Suryfnol 465). Use a 1.0mm nozzle air spray gun to evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and side walls. The coating thickness is 0.4mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0053] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0054] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0055] Example 7: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0056] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0057] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (60wt% large-particle magnetic powder with an average particle size of 80μm, 35wt% rubber matrix (polyurethane, Bolino, PU-956), and 5wt% additive Suryfnol 465). Use a 1.0mm nozzle air spray gun to evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The coating thickness should be 0.4mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0058] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 70mm inner diameter, 1000-turn magnetizing coil. Magnetize with a 15A magnetizing current for 5 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0059] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0060] Example 8: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0061] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0062] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (60wt% large-particle magnetic powder with an average particle size of 80μm, 35wt% rubber matrix (polyurethane, Bolino, PU-956), and 5wt% additive Suryfnol 465). Use a 1.0mm nozzle air spray gun to evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The coating thickness should be 0.4mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0063] Immerse the magnetic tile in a 25°C constant temperature water bath for 8 minutes. Immediately after removing it, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A magnetizing current for 3 seconds, ensuring the direction is consistent with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0064] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0065] Example 9: This example provides a method for detecting the residual magnetism of permanent magnet ferrite tiles.

[0066] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0067] Place the magnetic tile in a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the magnetic tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the magnetic tile dry with a lint-free cloth. Weigh 15g of ferrite magnetic powder-rubber matrix composite soft magnetic coating (60wt% magnetic powder, 35wt% rubber matrix (polyurethane, Bolino, PU-956), 5wt% additive Suryfnol 465). Using a 1.0mm nozzle air spray gun, evenly spray the soft magnetic auxiliary layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The coating thickness should be 0.4mm, with a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes. The magnetic powder contains 80wt% large particles with a particle size of 100μm and 20wt% small particles with a particle size of 8μm. Large-particle soft magnetic powder was treated with 3wt% KH-550 silane coupling agent at 60 degrees Celsius for 2 hours, and the mixture was stirred thoroughly to ensure uniform surface modification.

[0068] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0069] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0070] Comparative Example 1: This embodiment provides a method for detecting the residual magnetism of a permanent magnet ferrite tile.

[0071] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0072] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0073] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0074] Comparative Example 2: This embodiment provides a method for detecting the residual magnetism of a permanent magnet ferrite tile.

[0075] Testing method: Select a permanent magnet ferrite tile with specifications of R35-r30*30, and each end has a rectangular groove with a width of 8mm, a depth of 3mm, and a length of 10mm. Wipe the inner and outer curved surfaces, as well as the bottom and sidewalls of the grooves at both ends with a lint-free cloth. Wipe the bottom and sidewalls of the grooves with a cotton swab dipped in anhydrous ethanol to ensure that everything is clean and dry.

[0076] Place the magnetic tile into a 50mL graduated cylinder pre-filled with 30mL of deionized water. After slowly immersing the tile, the reading should be 37.2mL, with a volume of 7.2 cubic centimeters. Wipe the tile dry with a lint-free cloth. Weigh 15g of silicone and use a 1.0mm nozzle air spray gun to evenly spray a silicone layer onto the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls. The spray thickness should be 0.4mm, covering a total area of ​​1080 square millimeters. Allow it to air dry for 8 minutes.

[0077] Immerse the magnetic tile in a 20°C constant temperature water bath for 5 minutes. Immediately after removal, place it in the center of a 60mm inner diameter, 800-turn magnetizing coil. Magnetize with a 20A current for 3 seconds, ensuring the direction aligns with the thickness. After magnetization, allow it to cool to 20°C. Use tweezers to lift the soft magnetic auxiliary layer from one end and peel it cleanly along each surface. Wipe the surface with a lint-free cloth dampened with anhydrous ethanol.

[0078] Place the magnetic tile in the center of a Helmholtz coil (60mm inner diameter, 1000 turns), adjust the platform so that the geometric center coincides with the coil axis, connect the fluxmeter, zero the sample, and quickly remove it using a clamp. Read the magnetic flux Φ, and take the average of three measurements. Calculate the residual magnetism using Br = (Φ / V) × 1998. Repeat the test five times for multiple magnetic tiles from the same batch, and calculate the mean and standard deviation.

[0079] The above experimental data were compiled and plotted in Table 1.

[0080] Table 1. Test results of the examples and comparative examples.

[0081] project Mean remanence (Br) Gs Standard deviation of remanence Example 1 3847 12.3 Example 2 3842 13.1 Example 3 3845 13.0 Example 4 3846 12.5 Example 5 3849 12.4 Example 6 3838 13.6 Example 7 3844 12.9 Example 8 3845 13.2 Example 9 3846 11.3 Comparative Example 1 3708 37.6 Comparative Example 2 3686 41.2

[0082] As shown in Table 1, the average remanence (Br) values ​​of the embodiments are all higher than those of the comparative examples, and the standard deviations are all smaller than those of comparative examples 1-2. This is because the present invention significantly improves the uniformity of the magnetic field distribution in complex structural areas by uniformly coating a peelable soft magnetic auxiliary layer with a relative permeability of 10 to 100 times that of the magnetic tile body on the inner arc surface, outer arc surface, bottom of the grooves at both ends, and sidewalls of the magnetic tile. During magnetization, the auxiliary layer effectively guides the magnetic flux, eliminating magnetization dead zones and local incomplete magnetization. After magnetization, the auxiliary layer is completely peeled off without affecting the performance of the magnetic tile body. By accurately measuring the volume of the magnetic tile, combining the Helmholtz coil method to measure the magnetic flux, and converting the remanence through a standard formula, the accuracy and reliability of the test results are ensured. The experimental results verify that the deviation of the remanence is significantly reduced, and the test results are more reliable. Comparative example 1 has no auxiliary layer, the complex structure is not sufficiently magnetized, the average remanence value decreases, and the standard deviation increases significantly. Comparative example 2's non-magnetic coating material cannot guide the magnetic flux and cannot achieve the effect of this solution.

[0083] Among them, Example 9 showed the best results because it formed a chemical bonding layer on the surface of large particles through a silane coupling agent, which enhanced the interfacial bonding strength between the particles and the matrix; the large particles became stress concentration points and peeling initiation positions during peeling; the small particles formed stable aggregates with the large particles through physical coating and van der Waals forces; during the peeling process, the large particles drove the surrounding small particles to fall off as a whole, thereby significantly reducing the magnetic powder residue on the surface of the magnetic tile after peeling and further improving the detection accuracy.

[0084] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for detecting the residual magnetization of a permanent ferrite magnet tile, characterized in that, The method comprises the following steps: (1) surface cleaning treatment of the permanent magnet ferrite tile to be measured; (2) measurement of the volume of the tile; (3) uniform coating of a peelable soft magnetic auxiliary layer on the inner arc surface, outer arc surface, and both end groove bottom and sidewall of the tile, the relative magnetic permeability of the soft magnetic auxiliary layer being 10-100 times that of the tile body, and the spraying thickness being 0.2-0.6 mm; (4) after natural air drying of the soft magnetic auxiliary layer, constant temperature treatment of the tile; (5) placing the tile into the center of a magnetizing coil for saturation magnetization, the magnetizing direction being consistent with the thickness direction of the tile; (6) peeling off the soft magnetic auxiliary layer after magnetization; (7) measurement of the magnetic flux of the tile by the Helmholtz coil method, and conversion of the residual magnetization in combination with the volume data.

2. The method of claim 1, wherein, The soft magnetic auxiliary layer is a ferrite powder-rubber matrix composite coating, the content of the magnetic powder in the coating being 40-80 wt%, the content of the rubber matrix being 15-55 wt%, and the content of the auxiliary agent being 1-10 wt%.

3. The method of claim 2, wherein, The magnetic powder comprises large particle magnetic powder and small particle magnetic powder, the particle size of the large particle magnetic powder being 70-100 μm, and the particle size of the small particle magnetic powder being 2-10 μm, the surface of the large particle magnetic powder being treated by a silane coupling agent.

4. The method of claim 1, wherein, The soft magnetic auxiliary layer is sprayed by an air spray gun, the nozzle aperture being 0.5-1.5 mm.

5. The method of claim 1, wherein, The soft magnetic auxiliary layer is a peelable rubber magnetic tape or a soluble soft magnetic coating.

6. The method of claim 1, wherein, The volume measurement adopts the drainage method.

7. The method of claim 1, wherein, The constant temperature treatment is soaking the tile with the sprayed soft magnetic auxiliary layer in a constant temperature water tank at 15-30 degrees Celsius for 1-10 minutes.

8. The method of claim 1, wherein, The inner diameter of the magnetizing coil is 40-80 mm, the number of turns of the magnetizing coil is 600-1200 turns, the magnetizing current is 10-30 A, and the magnetizing time is 1-10 seconds.

9. The method of claim 1, wherein, The magnetic flux measurement adopts the Helmholtz coil method, the inner diameter of the Helmholtz coil being 40-80 mm, and the number of turns of the Helmholtz coil being 800-1200 turns.

10. The method of claim 1, wherein, The conversion formula of the residual magnetization Br is Br= (Φ / V) x 1998, Φ being the average value of the magnetic flux of the tile measured by the Helmholtz coil method and measured for 3 times, and V being the volume of the tile.