A pressure-resistant Mn-Zn ferrite core for a high-frequency induction heating furnace and a preparation method thereof

Abstract

The application discloses a high-frequency induction heating furnace pressure-resistant manganese-zinc ferrite core and a preparation method thereof, and belongs to the technical field of soft magnetic ferrite materials. The high-frequency induction heating furnace pressure-resistant manganese-zinc ferrite core comprises the following steps: mixing ferroferric oxide, manganese carbonate and zinc oxide, ball-milling to obtain main materials, pre-sintering in a muffle furnace to obtain pre-sintered materials; mixing the pre-sintered materials, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and a surfactant, ball-milling, drying, adding a binder, stirring and uniformly mixing to obtain mixed materials; and pressing and forming the mixed materials, calcining after obtaining a green body to obtain the pressure-resistant manganese-zinc ferrite core. The prepared pressure-resistant manganese-zinc ferrite core has high density, hardness, initial permeability and saturation magnetic induction intensity.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic ferrite materials technology, specifically to a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace and its preparation method. Background Technology

[0002] Manganese-zinc ferrite is a type of soft magnetic material with a spinel structure, possessing advantages such as high permeability, low coercivity, and low high-frequency loss. It is widely used in high-frequency transformers, inductors, and high-frequency induction heating equipment. Particularly in high-frequency induction furnaces, manganese-zinc ferrite cores can effectively concentrate the magnetic field and improve electromagnetic coupling efficiency, thereby enhancing heating efficiency and equipment stability. However, high-frequency induction furnaces typically operate at high frequencies and high power, requiring the core to withstand not only strong alternating magnetic fields but also certain mechanical compressive and thermal stresses. Traditional manganese-zinc ferrite cores are usually made from iron oxide, manganese carbonate, and zinc oxide as main raw materials, prepared through ball milling, pre-sintering, pressing, and high-temperature sintering. Due to severe agglomeration and poor particle dispersion, defects such as uneven density distribution, high porosity, and microcracks easily occur during the pressing process. This results in a loose internal structure of the sintered core, with low mechanical strength and compressive strength, making it difficult to meet the requirements for long-term stable operation of high-frequency induction furnaces.

[0003] Chinese invention patent CN110571039A discloses a method for manufacturing a manganese-zinc ferrite core, including the following steps: a) Particle inspection: inspecting the particle size of the purchased mixture; b) Pressing: pressing the mixture into a blank using a molding press; c) Sintering: sintering the blank in a sintering furnace to obtain a sintered product; d) Sintered product inspection: inspecting the appearance, dimensions, and electrical properties of the sintered product; e) Cutting: manually cutting the sintered product and placing it in layers; f) Grinding: grinding the sintered product using a grinding machine; g) Polishing: polishing the sintered product using a polishing device to obtain a finished product; h) Finished product inspection: inspecting the appearance, dimensions, and electrical properties of the finished product; i) Packaging: packaging the finished product for storage. However, the saturation magnetic induction intensity of the manganese-zinc ferrite core prepared by this invention is still insufficient. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a pressure-resistant manganese-zinc ferrite core for high-frequency induction heating furnaces and its preparation method.

[0005] A method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace includes the following steps: (1) Weigh out the following by weight: 68-72 parts of ferric oxide, 20-25 parts of manganese carbonate, 4-6 parts of zinc oxide, 0.5-1 parts of silicon dioxide, 2-4 parts of titanium dioxide, 1-2 parts of zirconium oxide, 0.04-0.1 parts of surfactant, 8-10 parts of binder, and 80 parts of deionized water; (2) After mixing ferric oxide, manganese carbonate and zinc oxide, the main material is obtained by ball milling and pre-calcining in a muffle furnace to obtain pre-calcined material; (3) After mixing the pre-burned material, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and surfactant, the mixture is ball-milled, dried, and then the binder is added and stirred to obtain a mixture. (4) Press the mixture into shape, and after obtaining the green embryo, calcine it to obtain a pressure-resistant manganese-zinc ferrite core; The structural formula of the surfactant is as follows: .

[0006] The adhesive is a 10wt% aqueous solution of polyvinyl alcohol.

[0007] In step (1), the pre-firing temperature is 900-1000℃ and the time is 2-3h.

[0008] In step (4), the pressure for pressing is 60-70 MPa.

[0009] In step (4), the calcination reaction temperature is 1200-1400℃.

[0010] In step (4), the calcination reaction time is 2-3 hours.

[0011] In step (4), the calcination heating rate is 5-10℃ / min.

[0012] The surfactant is prepared by the following method: S1: The reaction of 1,5-dichloropentane with 2-amino-1,3-propanediol yields intermediate 1, as illustrated in the following reaction equation:

[0013] S2: Intermediate 1 reacts with hexadecyl chloride to give intermediate 2, and the reaction equation is shown below:

[0014] S3: Intermediate 2 reacts with 1,3-propylsulfonyl lactone to yield a surfactant, as shown in the following schematic equation:

[0015] In step S1, the molar ratio of 1,5-dichloropentane to 2-amino-1,3-propanediol is 1:(2.05-2.08); in step S2, the molar ratio of intermediate 1 to hexadecane is 1:(2.03-2.05); in step S3, the molar ratio of intermediate 2 to 1,3-propylsulfonyl lactone is 1:(4.08-4.12).

[0016] A pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace is prepared by the method described above.

[0017] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: The pressure-resistant manganese-zinc ferrite core prepared by this invention has high density, hardness, initial permeability and saturation magnetic induction intensity. Attached Figure Description

[0018] Figure 1 The image shows a high-resolution mass spectrum of the surfactant prepared in Example 1. Detailed Implementation

[0019] Example 1 Preparation of Surfactants S1: 150 ml of tetrahydrofuran, 0.1 mol of 1,5-dichloropentane, 0.205 mol of 2-amino-1,3-propanediol, and 0.21 mol of potassium carbonate were added to a reaction vessel, stirred and mixed, and reacted at 40 °C for 4 h. After cooling to room temperature, the mixture was filtered, and the filtrate was washed with saturated brine (2 × 50 ml), dried with 20 g of anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated at 45 °C to constant weight to obtain intermediate 1; its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 4.35 (t, J = 5.2 Hz, 4H),3.54 – 3.34 (m, 10H), 3.08 (dt, J = 8.0, 4.4 Hz, 2H), 2.81 – 2.57 (m, 4H),1.52 – 1.41 (m, 4H), 1.39 – 1.26 (m, 2H); HRMS (m / z): 251.1895[M+H] + ; S2: Add 350 ml of acetonitrile, 0.1 mol of intermediate 1, 0.25 mol of potassium carbonate, and 0.02 mol of potassium iodide to a reaction flask, stir and mix well, heat to 70 °C, and add 0.203 mol of hexadecane chloride dropwise over 30 min. Let the reaction proceed for 7 h, cool to room temperature, filter, and rotary evaporate the filtrate at 50 °C to constant weight. Add 300 ml of deionized water, stir to precipitate, filter, wash the filter cake with 50 wt% ethanol aqueous solution (3 × 50 ml), and vacuum dry at 60 °C for 12 h to obtain intermediate 2; its 1H NMR data are as follows: 1 H NMR (400MHz, Chloroform- d ) δ 3.66 – 3.47 (m, 12H), 3.08 (p, J = 5.6 Hz, 2H), 2.72 –2.48 (m, 8H), 1.52 – 1.40 (m, 8H), 1.39 – 1.21 (m, 54H), 0.95 – 0.84 (m, 6H); HRMS (m / z): 699.6907[M+H] + ; S3: Under nitrogen protection, 800 ml of anhydrous tetrahydrofuran and 0.1 mol of intermediate 2 were added to a reaction flask and stirred until homogeneous. At 0°C, 0.45 mol of sodium hydride was added in 5 equal batches, with a 4-min interval between batches, and stirred for 30 min. Then, 200 ml of anhydrous DMF solution containing 0.408 mol of 1,3-propylsulfonate lactone was slowly added dropwise over 1 h. The mixture was heated to 50°C and reacted for 24 h. After cooling to 0°C, 100 ml of isopropanol was slowly added and stirred for 10 min. The mixture was then rotary evaporated at 50°C to constant weight. 500 ml of acetone was added and stirred to precipitate the precipitate. The precipitate was filtered, washed with 50 wt% acetone aqueous solution (2 × 80 ml), and dried under vacuum at 60°C for 12 h to obtain the surfactant. Its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, Methanol- d 4) δ 3.56 – 3.43 (m, 16H), 3.19 – 3.03 (m, 10H), 2.81 (dt, J = 12.4, 6.2 Hz, 4H), 2.70 (dt, J = 12.3, 6.2 Hz, 4H), 2.08 – 1.82 (m, 8H), 1.63 – 1.49 (m, 8H), 1.40 – 1.25 (m, 54H), 0.93 – 0.85 (m, 6H); its high-resolution mass spectrum is shown below. Figure 1 As shown, HRMS (m / z): 295.6695 [M-4Na] 4- .

[0020] Example 2 Preparation of Surfactants S1: Add 150 ml tetrahydrofuran, 0.1 mol 1,5-dichloropentane, 0.206 mol 2-amino-1,3-propanediol, and 0.21 mol potassium carbonate to a reaction vessel, stir and mix well, react at 35°C for 5 h, cool to room temperature, filter, wash the filtrate with saturated brine (2 × 50 ml), dry with 20 g anhydrous magnesium sulfate, filter, and rotary evaporate the filtrate at 45°C to constant weight to obtain intermediate 1; S2: Add 350 ml of acetonitrile, 0.1 mol of intermediate 1, 0.25 mol of potassium carbonate, and 0.02 mol of potassium iodide to a reaction flask, stir and mix well, heat to 65 °C, add 0.204 mol of hexadecane chloroplastane dropwise, and the addition is completed in 30 min. After reacting for 8 h, cool to room temperature, filter, and rotary evaporate the filtrate at 50 °C to constant weight. Add 300 ml of deionized water, stir to precipitate, filter, wash the filter cake with 50 wt% ethanol aqueous solution (3 × 50 ml), and vacuum dry at 60 °C for 12 h to obtain intermediate 2; S3: Under nitrogen protection, 800 ml of anhydrous tetrahydrofuran and 0.1 mol of intermediate 2 were added to a reaction flask and stirred until homogeneous. At 0°C, 0.45 mol of sodium hydride was added in batches (5 equal batches, 4 min apart), and stirred for 30 min. Then, 200 ml of anhydrous DMF solution containing 0.41 mol of 1,3-propylsulfonate lactone was slowly added dropwise over 1 h. The mixture was heated to 55°C and reacted for 22 h. After cooling to 0°C, 100 ml of isopropanol was slowly added and stirred for 10 min. The mixture was then rotary evaporated at 50°C to constant weight. 500 ml of acetone was added and stirred to precipitate the precipitate. The precipitate was filtered, washed with 50 wt% acetone aqueous solution (2 × 80 ml), and dried under vacuum at 60°C for 12 h to obtain the surfactant.

[0021] Example 3 Preparation of Surfactants S1: Add 150 ml of tetrahydrofuran, 0.1 mol of 1,5-dichloropentane, 0.208 mol of 2-amino-1,3-propanediol, and 0.21 mol of potassium carbonate to a reaction vessel, stir and mix well, react at 30 °C for 6 h, cool to room temperature, filter, wash the filtrate with saturated brine (2 × 50 ml), dry with 20 g of anhydrous magnesium sulfate, filter, and rotary evaporate the filtrate at 45 °C to constant weight to obtain intermediate 1; S2: Add 350 ml of acetonitrile, 0.1 mol of intermediate 1, 0.25 mol of potassium carbonate, and 0.02 mol of potassium iodide to a reaction flask, stir and mix well, heat to 60 °C, add 0.205 mol of hexadecane chloroplastane dropwise, and the addition is completed in 30 min. After reacting for 9 h, cool to room temperature, filter, and rotary evaporate the filtrate at 50 °C to constant weight. Add 300 ml of deionized water, stir to precipitate, filter, wash the filter cake with 50 wt% ethanol aqueous solution (3 × 50 ml), and vacuum dry at 60 °C for 12 h to obtain intermediate 2; S3: Under nitrogen protection, 800 ml of anhydrous tetrahydrofuran and 0.1 mol of intermediate 2 were added to a reaction flask and stirred until homogeneous. At 0°C, 0.45 mol of sodium hydride was added in 5 batches (4 min apart) and stirred for 30 min. Then, 200 ml of anhydrous DMF solution containing 0.412 mol of 1,3-propylsulfonate lactone was slowly added dropwise over 1 h. The mixture was heated to 60°C and reacted for 20 h. After cooling to 0°C, 100 ml of isopropanol was slowly added and stirred for 10 min. The mixture was then rotary evaporated at 50°C to constant weight. 500 ml of acetone was added and stirred to precipitate the precipitate. The precipitate was filtered and washed with 50 wt% acetone aqueous solution (2 × 80 ml). The precipitate was then dried under vacuum at 60°C for 12 h to obtain the surfactant.

[0022] Example 4: Preparation of a pressure-resistant manganese-zinc ferrite core (1) Weigh out: 68g of ferric oxide, 20g of manganese carbonate, 4g of zinc oxide, 0.5g of silicon dioxide, 2g of titanium dioxide, 1g of zirconium oxide, 0.04g of surfactant (prepared in Example 1), 8g of binder (10wt% polyvinyl alcohol aqueous solution), and 80g of deionized water; (2) Add ferric oxide, manganese carbonate and zinc oxide to a ball mill in sequence, using grinding balls with diameters of 5 mm and 10 mm. The weight ratio of 5 mm grinding balls to 10 mm grinding balls is 3:1, and the ball-to-material ratio is 10:1. Grind at 250 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 5 times to obtain the main material. Place it in a muffle furnace for pre-calcination, heat it to 900℃ at a rate of 5℃ / min, keep it at that temperature for 3 h, and let it cool naturally to room temperature to obtain the pre-calcined material. (3) Add the pre-burned material, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and surfactant to the ball mill in sequence. Use grinding balls with diameters of 3 mm and 6 mm. The weight ratio of 3 mm grinding balls to 6 mm grinding balls is 2:1 and the ball-to-material ratio is 11:1. Grind at 280 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 10 times to obtain a mixed slurry. After filtration, dry at 100℃ for 12 h, add binder, and stir at 300 rpm for 30 min to obtain a mixture. (4) The mixture is placed in a ring mold (φ20mm×φ10mm×5mm), pressed at 60MPa at room temperature, and held for 20s to obtain a blank. The blank is placed in a tube furnace, and a mixture of nitrogen and oxygen is introduced at a flow rate of 1L / min and an oxygen volume ratio of 1.9%. The temperature is raised to 300℃ at a rate of 5℃ / min and held for 30min. Then the temperature is raised to 1200℃ at a rate of 5℃ / min and calcined for 3h. The core is then naturally cooled to room temperature to obtain a pressure-resistant manganese-zinc ferrite core.

[0023] Example 5: Preparation of a pressure-resistant manganese-zinc ferrite core (1) Weigh out: 70g of ferric oxide, 23g of manganese carbonate, 5g of zinc oxide, 0.8g of silicon dioxide, 3g of titanium dioxide, 1.5g of zirconium oxide, 0.08g of surfactant (prepared in Example 2), 9g of binder (10wt% polyvinyl alcohol aqueous solution), and 80g of deionized water; (2) Add ferric oxide, manganese carbonate and zinc oxide to a ball mill in sequence, using grinding balls with diameters of 5 mm and 10 mm. The weight ratio of 5 mm grinding balls to 10 mm grinding balls is 3:1, and the ball-to-material ratio is 10:1. Grind at 250 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 5 times to obtain the main material. Place it in a muffle furnace for pre-calcination, heat it to 950℃ at a rate of 5℃ / min, keep it at that temperature for 2.5 h, and cool it naturally to room temperature to obtain the pre-calcined material. (3) Add the pre-burned material, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and surfactant to the ball mill in sequence. Use grinding balls with diameters of 3 mm and 6 mm. The weight ratio of 3 mm grinding balls to 6 mm grinding balls is 2:1 and the ball-to-material ratio is 11:1. Grind at 280 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 10 times to obtain a mixed slurry. After filtration, dry at 100℃ for 12 h, add binder, and stir at 300 rpm for 30 min to obtain a mixture. (4) The mixture is placed in a ring mold (φ20mm×φ10mm×5mm), pressed at 65MPa at room temperature, and held for 20s to obtain a blank. The blank is placed in a tube furnace, and a mixture of nitrogen and oxygen is introduced at a flow rate of 1L / min and an oxygen volume ratio of 1.9%. The temperature is raised to 300℃ at a rate of 8℃ / min and held for 30min. Then the temperature is raised to 1300℃ at a rate of 8℃ / min and calcined for 2.5h. The core is then naturally cooled to room temperature to obtain a pressure-resistant manganese-zinc ferrite core.

[0024] Example 6: Preparation of a pressure-resistant manganese-zinc ferrite core (1) Weigh out: 72g of ferric oxide, 25g of manganese carbonate, 6g of zinc oxide, 1g of silicon dioxide, 4g of titanium dioxide, 2g of zirconium oxide, 0.1g of surfactant (prepared in Example 3), 10g of binder (10wt% polyvinyl alcohol aqueous solution), and 80g of deionized water; (2) Add ferric oxide, manganese carbonate and zinc oxide to a ball mill in sequence, using grinding balls with diameters of 5 mm and 10 mm. The weight ratio of 5 mm grinding balls to 10 mm grinding balls is 3:1, and the ball-to-material ratio is 10:1. Grind at 250 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 5 times to obtain the main material. Place it in a muffle furnace for pre-calcination, heat it to 1000℃ at a rate of 5℃ / min, hold it for 2 h, and cool it naturally to room temperature to obtain the pre-calcined material. (3) Add the pre-burned material, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and surfactant to the ball mill in sequence. Use grinding balls with diameters of 3 mm and 6 mm. The weight ratio of 3 mm grinding balls to 6 mm grinding balls is 2:1 and the ball-to-material ratio is 11:1. Grind at 280 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 10 times to obtain a mixed slurry. After filtration, dry at 100℃ for 12 h, add binder, and stir at 300 rpm for 30 min to obtain a mixture. (4) The mixture is placed in a ring mold (φ20mm×φ10mm×5mm), pressed at 70MPa at room temperature, and held for 20s to obtain a blank. The blank is placed in a tube furnace, and a mixture of nitrogen and oxygen is introduced at a flow rate of 1L / min and an oxygen volume ratio of 1.9%. The temperature is raised to 300℃ at a rate of 10℃ / min and held for 30min. Then the temperature is raised to 1400℃ at a rate of 10℃ / min and calcined for 2h. The core is then naturally cooled to room temperature to obtain a pressure-resistant manganese-zinc ferrite core.

[0025] Comparative Example 1 The preparation method of the pressure-resistant manganese-zinc ferrite core is basically the same as that in Example 5, except that titanium dioxide is not added to the composition.

[0026] Comparative Example 2 The preparation method of the pressure-resistant manganese zinc ferrite core is basically the same as that in Example 5, except that in step (4), the heating rate of calcination is 20℃ / min.

[0027] Comparative Example 3 The preparation method of the pressure-resistant manganese zinc ferrite core is basically the same as that in Example 5, except that the calcination time in step (4) is 5h.

[0028] Comparative Example 4 Preparation of pressure-resistant manganese-zinc ferrite cores: (1) Weigh out: 70g of ferric oxide, 23g of manganese carbonate, 5g of zinc oxide, 0.8g of silicon dioxide, 3g of titanium dioxide, 1.5g of zirconium oxide, 0.08g of surfactant (prepared in Example 2), 9g of binder (10wt% polyvinyl alcohol aqueous solution), and 80g of deionized water; (2) Add ferric oxide, manganese carbonate and zinc oxide to a ball mill in sequence, using grinding balls with diameters of 5 mm and 10 mm. The weight ratio of 5 mm grinding balls to 10 mm grinding balls is 3:1, and the ball-to-material ratio is 10:1. Grind at 250 r / min for 30 min, stop for 15 min, and repeat the ball milling and stopping process 5 times to obtain the main material. Place it in a muffle furnace for pre-calcination, heat it to 950℃ at a rate of 5℃ / min, keep it at that temperature for 2.5 h, and cool it naturally to room temperature to obtain the pre-calcined material. (3) Mix the pre-burned material, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and surfactant, stir at 300 rpm for 30 min to form a slurry; filter and dry at 100℃ for 12 h, add binder, stir at 300 rpm for 30 min to obtain a mixture; (4) The mixture is placed in a ring mold (φ20mm×φ10mm×5mm), pressed at 65MPa at room temperature, and held for 20s to obtain a blank. The blank is placed in a tube furnace, and a mixture of nitrogen and oxygen is introduced at a flow rate of 1L / min and an oxygen volume ratio of 1.9%. The temperature is raised to 300℃ at a rate of 8℃ / min and held for 30min. Then the temperature is raised to 1300℃ at a rate of 8℃ / min and calcined for 2.5h. The core is then naturally cooled to room temperature to obtain a pressure-resistant manganese-zinc ferrite core.

[0029] Comparative Example 5 The preparation method of the pressure-resistant manganese-zinc ferrite core is basically the same as that in Example 5, except that the surfactant is replaced with an equal weight of a surfactant prepared by the following method: The preparation method of the surfactant is basically the same as that in Example 2, except that 2-amino-1,3-propanediol in step S1 is replaced with an equimolar amount of ethanolamine, and 1,3-propylsulfonate in step S3 is replaced with 0.205 mol.

[0030] Comparative Example 6 The preparation method of the pressure-resistant manganese-zinc ferrite core is basically the same as that in Example 5, except that the surfactant is replaced with an equal weight of a surfactant prepared by the following method: The preparation method of the surfactant is basically the same as that in Example 2, except that 1,5-dichloropentane in step S1 is replaced with an equimolar amount of 1,2-bis(2-chloroethoxy)ethane.

[0031] Comparative Example 7 The preparation method of the pressure-resistant manganese-zinc ferrite core is basically the same as that in Example 5, except that the surfactant is replaced with an equal weight of a surfactant prepared by the following method: The preparation method of the surfactant is basically the same as that in Example 2, except that the hexadecyl chloride in step S2 is replaced with an equimolar amount of hexane chloride.

[0032] The polyvinyl alcohol used in this application is PVA 17-88.

[0033] The density of the pressure-resistant manganese-zinc ferrite cores prepared in the examples and comparative examples was tested using the Archimedes' displacement method. The test method is as follows: Accurately weigh the manganese-zinc ferrite core to a mass m1; fill a beaker with an appropriate amount of deionized water (enough to completely submerge the sample), place it on a balance, and zero the balance; secure the manganese-zinc ferrite core firmly with a thin thread, ensuring it is completely submerged in the water without touching the bottom, and record the balance reading m2. At this point, the buoyancy force on the manganese-zinc ferrite core is F = (m1 - m2)g = ρ. 水 gV, where ρ 水 The density of deionized water is given; calculate the density of the manganese-zinc ferrite core using the following formula:

[0034] The hardness of the pressure-resistant manganese-zinc ferrite core was tested using an HV-1000ZDT hardness tester, with a test load of 200g and a loading time of 10s. The inductance of the pressure-resistant manganese-zinc ferrite core was tested using an Agilent E4980A impedance analyzer under the conditions of f=100kHz, U=0.5V, and T=25℃, and the initial permeability of the sample was calculated. The saturation magnetic induction intensity was tested using an SK110-MTR2655 DC magnetization characteristic tester under the conditions of H=1194A / m and T=25℃. The test results are shown in Table 1.

[0035] Table 1 Performance Test Data

[0036] As can be seen from the data in Table 1, the pressure-resistant manganese-zinc ferrite core prepared by the present invention has high density, hardness, initial permeability and saturation magnetic induction intensity.

[0037] This invention promotes partial spinelization of the main phases (ferric oxide, manganese carbonate, and zinc oxide) in the raw materials through pre-sintering treatment, resulting in fewer chemical reactions and more stable finished product performance during the final sintering process. The introduction of components such as silica, titanium dioxide, and zirconium oxide synergistically regulates the grain boundary structure. A two-step ball milling process is employed to achieve highly uniform dispersion of each component. Simultaneously, surfactants improve slurry stability and particle dispersibility. Through the sintering process, grain size and densification are precisely controlled, reducing porosity and defects. This results in a manganese-zinc ferrite core that simultaneously possesses high density, hardness, initial permeability, and saturation magnetic induction, achieving a synergistic improvement in both mechanical and magnetic properties.

[0038] The surfactant added to the pressure-resistant manganese-zinc ferrite magnetic core prepared in this invention has a methylene chain as its core, linked by two long-chain alkyl groups and four sulfonate groups. The sulfonate groups can adsorb onto the surface of granules (such as ferric oxide, manganese carbonate, and zinc oxide) through electrostatic and coordination interactions, thereby generating an electrostatic repulsion effect, preventing granule agglomeration and improving dispersion uniformity. The long-chain alkyl groups can effectively reduce the surface energy of the granules, improve their flowability, and enable closer packing during compression molding, increasing green density and reducing porosity. The methylene chain further enhances the adsorption stability with metal particles through hydrophobic interactions, and through conformational adjustment, the sulfonate groups can be more fully attached to the surface of the metal oxide particles, while the hydrophobic long chains extend in an orderly manner, further improving the green density. The synergistic effect of the multifunctional groups of surfactants helps to form a high-density and uniform microstructure, which greatly reduces the sources of electric field concentration such as pores. At the same time, due to the refinement of grains and the uniformity of the structure, the resistance to the movement of magnetic domain walls is reduced, which allows the initial magnetic permeability of the material to be maintained or improved. In addition, high density and good crystallinity are also conducive to maintaining a high saturation magnetic induction intensity, thereby achieving a synergistic improvement in mechanical and magnetic properties.

[0039] In Comparative Example 2, the excessively rapid heating rate and insufficient diffusion time during calcination prevented uniform grain growth. This also led to stress concentration and porosity defects within the grains and at grain boundaries, resulting in low initial permeability and saturation magnetic induction. In Comparative Example 3, the excessively long holding time during calcination caused abnormal grain growth (overheating), weakening the grain boundary's control over magnetic domain walls. Furthermore, excessive growth resulted in internal stress accumulation and microcrack formation, reducing the material's mechanical strength and density uniformity. In Comparative Example 5, the surfactant molecule contained only two sulfonate groups, reducing adsorption sites, resulting in insufficient negative charge on the particle surface, weakened electrostatic repulsion, and decreased dispersion stability. During sintering, the agglomerated regions were difficult to densify sufficiently, increasing residual porosity and ultimately reducing overall density. In Comparative Example 6, the surfactant used had a polyether chain segment as its core, leading to decreased directional adsorption capacity on the particle surface. Simultaneously, excessive flexibility resulted in a loose adsorption layer structure, making it difficult to form an effective steric hindrance layer, further reducing dispersion stability. During sintering, the agglomerated regions were difficult to densify sufficiently, ultimately reducing overall density and performance.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 68-72 parts of ferric oxide, 20-25 parts of manganese carbonate, 4-6 parts of zinc oxide, 0.5-1 parts of silicon dioxide, 2-4 parts of titanium dioxide, 1-2 parts of zirconium oxide, 0.04-0.1 parts of surfactant, 8-10 parts of binder, and 80 parts of deionized water; (2) After mixing ferric oxide, manganese carbonate and zinc oxide, the main material is obtained by ball milling and pre-calcining in a muffle furnace to obtain pre-calcined material; (3) After mixing the pre-burned material, silicon dioxide, titanium dioxide, zirconium oxide, deionized water and surfactant, the mixture is ball-milled, dried, and then the binder is added and stirred to obtain a mixture. (4) Press the mixture into shape, and after obtaining the green embryo, calcine it to obtain a pressure-resistant manganese-zinc ferrite core; The structural formula of the surfactant is as follows: 。 2. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, The adhesive is a 10wt% aqueous solution of polyvinyl alcohol.

3. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, In step (1), the pre-firing temperature is 900-1000℃ and the time is 2-3h.

4. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, In step (4), the pressure for pressing is 60-70 MPa.

5. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, In step (4), the calcination reaction temperature is 1200-1400℃.

6. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, In step (4), the calcination reaction time is 2-3 hours.

7. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, In step (4), the calcination heating rate is 5-10℃ / min.

8. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 1, characterized in that, The surfactant is prepared by the following method: S1: The reaction of 1,5-dichloropentane with 2-amino-1,3-propanediol yields intermediate 1. S2: Intermediate 1 reacts with hexadecyl chloride to give intermediate 2. S3: Intermediate 2 reacts with 1,3-propylsulfonate lactone to obtain a surfactant.

9. The method for preparing a pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace according to claim 8, characterized in that, In step S1, the molar ratio of 1,5-dichloropentane to 2-amino-1,3-propanediol is 1:(2.05-2.08); in step S2, the molar ratio of intermediate 1 to hexadecane is 1:(2.03-2.05); in step S3, the molar ratio of intermediate 2 to 1,3-propylsulfonyl lactone is 1:(4.08-4.12).

10. A pressure-resistant manganese-zinc ferrite core for a high-frequency induction heating furnace, characterized in that, It is prepared by the method described in any one of claims 1-9.

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