Low-temperature sintered manganese-zinc wave-absorbing ferrite and preparation method thereof

Abstract

The application provides a low-temperature sintered manganese-zinc wave-absorbing ferrite and a preparation method thereof. The low-temperature sintered manganese-zinc wave-absorbing ferrite comprises main materials, fluxing agents, dispersing agents, additives and lubricants. The main materials comprise iron phosphate, iron nitrate, zinc sulfate and manganese nitrate. The fluxing agents are nano lead acetate and nano silver nitrate. The main materials selected by the application comprise iron phosphate, which can optimize the electromagnetic wave absorption performance. The doping of phosphorus adjusts the complex permittivity and complex permeability of the material, so that the material has higher magnetic resonance and dielectric properties in a specific frequency range, thereby more effectively absorbing electromagnetic waves and converting them into heat energy, reducing the reflection and interference of electromagnetic waves. The application further adds nano lead acetate and nano silver nitrate as fluxing agents, which can form grain boundaries during low-temperature sintering of the ferrite, so that the sintering is carried out in the form of liquid-phase sintering, thereby significantly promoting the transfer of substances in the sintering process, realizing low-temperature densification of the material, reducing the sintering temperature and improving the wave-absorbing performance.

Description

Technical Field

[0001] The invention belongs to the field of magnetic functional materials, and in particular relates to a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. Background Art

[0002] The continuous development of communication technology has facilitated human communication and significantly improved the efficiency of information transmission. However, the electromagnetic radiation and electromagnetic interference generated by electronic products can pose a certain degree of harm to people's health and work and life. As a result, people have begun to pay attention to the issue of electromagnetic pollution, and the research and development of high-performance absorbing materials has become a research hotspot in recent years.

[0003] Ferrite materials possess the ability to absorb broadband electromagnetic waves. Their excellent corrosion resistance and high-temperature resistance make them a preferred choice for electromagnetic wave absorbers. However, the ferrite preparation process requires high-temperature sintering, which conflicts with the green development concept of energy conservation and emission reduction. The sintering process is the most critical step in the ferrite preparation process, directly affecting the degree of solid-phase reaction, grain growth, and component diffusion, ultimately affecting the ferrite's microstructure and electromagnetic properties. Therefore, researchers have conducted extensive research on its formulation and process.

[0004] Chinese invention patent publication number CN118184328A discloses a low-temperature sintered, high-frequency, low-loss MnZn power ferrite and its preparation method. By replacing traditional V2O5 with Sb2O3, the ferrite's high-frequency loss is reduced while lowering the sintering temperature. However, the introduction of antimony oxide can cause antimony ions to enter the ferrite's lattice structure, disrupting the original magnetic interactions between ions and reducing magnetic permeability. This can lead to unstable inductance and affect the circuit's filtering, resonance, and other performance. Chinese invention patent publication number CN118084475A discloses a low-temperature sintered, ultra-low permeability NiCuZn material and its preparation method. By using a specific ratio of CaCO3, WO3, and Bi2O3 to interact with the main components, the material's magnetic properties and sintering performance are affected, improving the material's microstructure and achieving low-temperature sintering while also achieving low magnetic loss and a high Q value. However, due to the different application areas of absorbing ferrites, this material and its formulation cannot be applied to absorbing ferrites. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to obtain ferrite with good wave absorbing performance while reducing the sintering temperature.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] The first aspect of the present invention provides a low-temperature sintered manganese-zinc absorbing ferrite, comprising a main material, a flux, a dispersant, an additive and a lubricant;

[0008] The main ingredients include ferric phosphate, ferric nitrate, zinc sulfate and manganese nitrate, and the molar ratio of the ferric phosphate, ferric nitrate, zinc sulfate and manganese nitrate is 2:2:1:1;

[0009] The flux is nano-lead acetate and nano-silver nitrate, wherein the nano-lead acetate accounts for 0.02-0.04% of the mass of the main material, and the nano-silver nitrate accounts for 0.1-0.5% of the mass of the primary powder;

[0010] The additive is a mixture of copper oxide, calcium oxide and niobium oxide, wherein the copper oxide accounts for 1.1-3.3% of the main material, the calcium oxide accounts for 0.04-0.1% of the main material, and the niobium oxide accounts for 0.33-0.52% of the main material.

[0011] Beneficial effects: The main materials selected by the present invention include iron phosphate, which can optimize the electromagnetic wave absorption performance. The doping of phosphorus adjusts the complex dielectric constant and complex magnetic permeability of the material, so that it has higher magnetic resonance and dielectric properties within a specific frequency range, thereby more effectively absorbing electromagnetic waves and converting them into heat energy, reducing the reflection and interference of electromagnetic waves.

[0012] The present invention also adds nano-lead acetate and nano-silver nitrate as fluxes, which can form grain boundaries during low-temperature sintering of ferrite, allowing sintering to proceed in a liquid-phase sintering manner, thereby significantly promoting the transfer of substances during the sintering process, achieving low-temperature densification of the material, and improving the wave absorption performance while reducing the sintering temperature.

[0013] The present invention also adds a mixture of copper oxide, calcium oxide and niobium oxide, which interacts with the main material during the sintering process to occupy the oxygen ions to form octahedral spaces, promote the formation of grain boundaries, refine the grains, and improve the material's wave absorbing performance.

[0014] Preferably, the dispersant is a mixture of triammonium citrate and ammonium polymethacrylate, wherein the triammonium citrate accounts for 0.1-0.5% of the mass of the main material, and the ammonium polymethacrylate accounts for 0.1-0.5% of the mass of the main material.

[0015] Preferably, the lubricant is a mixture of fumed aluminum oxide, niobium diselenide and molybdenum disulfide, wherein the fumed aluminum oxide accounts for 0.05-0.1% of the main material by mass, the niobium diselenide accounts for 0.1-0.2% of the main material by mass, and the molybdenum disulfide accounts for 0.1-0.2% of the main material by mass.

[0016] Beneficial effects: In the present invention, fumed alumina, niobium diselenide and molybdenum disulfide are added as lubricants. The fumed alumina can be orderly combined on the surface of the matrix particles to form a shell layer. This shell layer effectively reduces the electrostatic attraction between the particles, avoids powder adhesion caused by van der Waals forces, moisture absorption, particle friction, etc., thereby improving the fluidity of the powder. The powder with good fluidity can be more fully filled in the mold, and then the high-density ferrite obtained by pressing is obtained.

[0017] During the pressing process of ferrite powder, niobium diselenide is rapidly transformed into a liquid lubricating film due to the increase in pressure, which plays a lubricating role. The niobium element in it will form crystal nuclei during the sintering process, promote the homogenization of the grains, reduce the sintering temperature and improve the absorption performance.

[0018] Molybdenum disulfide is a type of transition metal chalcogenide and a non-centrosymmetric material. Its high specific surface area and polymorphism give it excellent electronic properties. At the same time, the change in layer thickness caused by the quantum confinement effect can change the band gap of molybdenum disulfide, thereby achieving lubrication while improving the absorption performance.

[0019] The second aspect of the present invention provides a method for preparing the above-mentioned low-temperature sintered manganese-zinc absorbing ferrite, comprising the following steps:

[0020] S1: placing the main material and dispersant in water, stirring, adding ammonia water to adjust the pH, heating, keeping warm, baking, and keeping warm again to obtain a powder;

[0021] S2 calcining the powder, and mixing the calcined powder with flux, additives, lubricant and water by ball milling to obtain a slurry;

[0022] S3 adds PVA solution to the slurry for spray granulation, then performs bidirectional pressing, and finally uses a gradient temperature increase method for low-temperature sintering to obtain manganese zinc absorbing ferrite.

[0023] Beneficial effects: The present invention adds triammonium citrate and ammonium polymethacrylate of ionic polymers, which have good water absorption, adhesion and dispersibility, and can improve the stability of ferrite slurry and change its rheological properties during the ball milling process.

[0024] Preferably, in S1, the pH is adjusted to 6.2-8.0, the heating temperature is 80-90°C, and the baking temperature is 200-300°C.

[0025] Preferably, in S2, the calcination temperature is 900-950° C., and the calcination time is 1.5-2.0 h.

[0026] Preferably, in S2, stainless steel balls are added during the ball milling process, and the mass of the added stainless steel balls is 4 times the mass of the main material; the ball milling time is 60-80 min, and the ball milling speed is 400-450 r / min.

[0027] Preferably, in S2, the mass of the added water is the same as the mass of the main ingredient.

[0028] Preferably, in said S3, the pressure of bidirectional pressing is 0.5-1.0t / cm 2 .

[0029] Preferably, the gradient heating method is as follows: heating from room temperature to 120°C and keeping warm for 1 hour, then heating to 400°C and keeping warm for 1 hour, then heating to 500°C and keeping warm for 4 hours, then heating to 950°C and keeping warm for 1 hour, then heating to 1100°C and keeping warm for 8 hours, and finally cooling to room temperature with the furnace, with a heating rate of 3-5°C / min.

[0030] Beneficial effect: The present invention uses a low-temperature sintering method with a gradient temperature increase, especially heat preservation at 100℃ and 400℃, which can fully eliminate the moisture contained in the material and prevent Fe 2+ At the same time, the slower heating rate can also effectively prevent the deformation or even cracking of the blank caused by rapid evaporation of water. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0032] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0033] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0034] A low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof, comprising a main material, a flux, a dispersant, an additive and a lubricant;

[0035] The main ingredients include ferric phosphate, ferric nitrate, zinc sulfate and manganese nitrate, and the molar ratio of the ferric phosphate, ferric nitrate, zinc sulfate and manganese nitrate is 2:2:1:1;

[0036] The flux is nano-lead acetate and nano-silver nitrate, wherein the nano-lead acetate accounts for 0.02-0.04% of the main material weight, and the nano-silver nitrate accounts for 0.1-0.5% of the main material weight;

[0037] The dispersant is a mixture of triammonium citrate and ammonium polymethacrylate, wherein the triammonium citrate accounts for 0.1-0.5% of the mass of the main material, and the ammonium polymethacrylate accounts for 0.1-0.5% of the mass of the main material;

[0038] The additive is a mixture of copper oxide, calcium oxide and niobium oxide, wherein the copper oxide accounts for 1.1-3.3% of the mass of the main material, the calcium oxide accounts for 0.04-0.1% of the mass of the main material, and the niobium oxide accounts for 0.33-0.52% of the mass of the main material;

[0039] The lubricant is a mixture of fumed aluminum oxide, niobium diselenide and molybdenum disulfide, wherein the fumed aluminum oxide accounts for 0.05-0.1% of the main material mass, the niobium diselenide accounts for 0.1-0.2% of the main material mass, and the molybdenum disulfide accounts for 0.1-0.2% of the main material mass.

[0040] A method for preparing low-temperature sintered manganese-zinc absorbing ferrite specifically comprises the following steps:

[0041] S1: placing the main material and dispersant in water and stirring, adding ammonia water to adjust the pH, heating, keeping warm, baking, and keeping warm again to obtain powder; the adjusted pH is 6.2-8.0, the heating temperature is 80-90°C, and the baking temperature is 200-300°C.

[0042] S2 calcines the powder, and mixes the calcined powder with flux, additives, lubricant and water through ball milling to obtain a slurry; the calcination temperature is 900-950°C, and the calcination time is 1.5-2.0h; stainless steel balls are added during the ball milling process, and the mass of the added stainless steel balls is 4 times the mass of the main material; the ball milling time is 60-80min, and the ball milling speed is 400-450r / min; the mass of the added water is the same as the mass of the main material.

[0043] S3: Add the slurry to the PVA solution for spray granulation, then perform bidirectional pressing, and finally perform low-temperature sintering using a gradient heating method to obtain manganese zinc absorbing ferrite. The bidirectional pressing pressure is 0.5-1.0t / cm 2 ; The specific gradient heating method is: heat from room temperature to 120℃ and keep it for 1 hour, then heat to 400℃ and keep it for 1 hour, then heat to 500℃ and keep it for 4 hours, then heat to 950℃ and keep it for 1 hour, then heat to 1100℃ and keep it for 8 hours, and finally cool to room temperature with the furnace. The heating rate is 3-5℃ / min.

[0044] Example 1

[0045] This embodiment provides a low-temperature sintered manganese zinc absorbing ferrite and a preparation method thereof, as follows:

[0046] A low-temperature sintered manganese-zinc absorbing ferrite, comprising a main material, a flux, a dispersant, an additive and a lubricant;

[0047] The main ingredients include 302g of iron phosphate, 484g of iron nitrate, 161g of zinc sulfate and 179g of manganese nitrate, wherein the molar ratio of iron phosphate, iron nitrate, zinc sulfate and manganese nitrate is 2:2:1:1.

[0048] The flux is nano-lead acetate and nano-silver nitrate, the mass of the nano-lead acetate is 0.23g, and the mass of the nano-silver nitrate is 1.13g.

[0049] The dispersant is a mixture of triammonium citrate and ammonium polymethacrylate, the mass of the triammonium citrate is 2.25 g, and the mass of the ammonium polymethacrylate is 1.13 g.

[0050] The additive is a mixture of copper oxide, calcium oxide and niobium oxide, wherein the mass of the copper oxide is 23.65 g, the mass of the calcium oxide is 0.56 g, and the mass of the niobium oxide is 4.50 g.

[0051] The lubricant is a mixture of fumed aluminum oxide, niobium diselenide, and molybdenum disulfide. The mass of the fumed aluminum oxide is 0.56 g, the mass of the niobium diselenide is 1.13 g, and the mass of the molybdenum disulfide is 1.13 g.

[0052] The specific preparation method is as follows:

[0053] S1: Add the main ingredients and dispersant into distilled water, slowly add ammonia water to adjust the pH value to 6.5, heat to 80℃, keep warm for 2 hours to obtain gel, heat the gel to 220℃ and bake, keep warm for 2 hours to obtain powder.

[0054] S2 calcined the powder at a temperature of 900°C for 2.0 h; used a ball mill to evenly mix the additives, flux, and lubricant with the calcined powder, and added 1126 g of distilled water and 4504 g of stainless steel balls. The ball milling speed was 400 r / min and the ball milling time was 60 min to obtain a slurry.

[0055] S3 adds 112.6g of PVA solution with a concentration of 10% to the slurry and stirs evenly, then spray granulates to obtain granules; the granules are placed in a mold for bidirectional pressing with a pressing pressure of 0.6t / cm2, and then low-temperature sintering is performed using a gradient heating method, specifically, heating from room temperature to 120°C and keeping warm for 1h, then heating to 400°C and keeping warm for 1h, then heating to 500°C and keeping warm for 4h, then heating to 950°C and keeping warm for 1h, then heating to 1100°C and keeping warm for 8h, the heating rate is set to 3°C / min, and finally cooled to room temperature with the furnace to obtain manganese zinc absorbing ferrite.

[0056] Example 2

[0057] This embodiment provides a low-temperature sintered manganese zinc absorbing ferrite and a preparation method thereof, as follows:

[0058] A low-temperature sintered manganese-zinc absorbing ferrite, comprising a main material, a flux, a dispersant, an additive and a lubricant;

[0059] The main ingredients include 302g of iron phosphate, 484g of iron nitrate, 161g of zinc sulfate and 179g of manganese nitrate, wherein the molar ratio of iron phosphate, iron nitrate, zinc sulfate and manganese nitrate is 2:2:1:1.

[0060] The flux is nano-lead acetate and nano-silver nitrate, the mass of the nano-lead acetate is 0.45g, and the mass of the nano-silver nitrate is 4.50g.

[0061] The dispersant is a mixture of triammonium citrate and ammonium polymethacrylate, the mass of the triammonium citrate is 2.82 g, and the mass of the ammonium polymethacrylate is 1.69 g.

[0062] The additive is a mixture of copper oxide, calcium oxide and niobium oxide, wherein the mass of the copper oxide is 13.51 g, the mass of the calcium oxide is 1.13 g, and the mass of the niobium oxide is 5.63 g.

[0063] The lubricant is a mixture of fumed aluminum oxide, niobium diselenide, and molybdenum disulfide. The mass of the fumed aluminum oxide is 0.79 g, the mass of the niobium diselenide is 2.25 g, and the mass of the molybdenum disulfide is 2.25 g.

[0064] The specific preparation method is as follows:

[0065] S1: Add the main ingredients and dispersant into distilled water, slowly add ammonia water to adjust the pH value to 7.2, heat to 90°C, keep warm for 1.5 hours to obtain gel, heat the gel to 350°C for baking, and keep warm for 1.5 hours to obtain powder.

[0066] S2 calcined the powder at a temperature of 950°C for 1.5 hours; used a ball mill to evenly mix the additives, flux, and lubricant with the calcined powder, and added 1126g of distilled water and 4504g of stainless steel balls. The ball milling speed was 450r / min and the ball milling time was 60min to obtain a slurry.

[0067] S3 adds 112.6g of PVA solution with a concentration of 10% to the slurry and stirs evenly, then spray granulates to obtain granules; the granules are placed in a mold for bidirectional pressing with a pressing pressure of 0.8t / cm2, and then low-temperature sintering is performed using a gradient heating method, specifically, heating from room temperature to 120℃ and keeping warm for 1h, then heating to 400℃ and keeping warm for 1h, then heating to 500℃ and keeping warm for 4h, then heating to 950℃ and keeping warm for 1h, then heating to 1100℃ and keeping warm for 8h, the heating rate is set to 4℃ / min, and finally cooled to room temperature with the furnace to obtain manganese zinc absorbing ferrite.

[0068] Comparative Example 1

[0069] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 1 is that: there is no iron phosphate in the main material, and it is all iron nitrate, and the mass of iron nitrate is 786g; the preparation method is the same.

[0070] Comparative Example 2

[0071] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. This comparative example differs from Example 1 in that no dispersant is used, and no dispersant is added in S1. The other steps are the same.

[0072] Comparative Example 3

[0073] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 1 is that the additive is a mixture of titanium dioxide, copper oxide and silicon dioxide, the mass of titanium dioxide is 23.65g, the mass of copper oxide is 0.56g, and the mass of silicon dioxide is 4.50g. The preparation method is the same.

[0074] Comparative Example 4

[0075] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 1 is that the flux is vanadium pentoxide, the mass of vanadium pentoxide is 1.36 g, and the preparation method is the same.

[0076] Comparative Example 5

[0077] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 1 is that the lubricant is zinc stearate, the mass of zinc stearate is 2.82 g, and the preparation method is the same.

[0078] Comparative Example 6

[0079] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 1 is that: the preparation method is different, and the gradient heating method is not used for low-temperature sintering in S3. Specifically, the temperature is raised from room temperature to 1100°C and kept warm for 8 hours; then the temperature is cooled to room temperature with the furnace to obtain the manganese-zinc absorbing ferrite. The other steps are the same.

[0080] Comparative Example 7

[0081] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that the main ingredients of iron phosphate and iron nitrate are replaced with iron sulfate, the mass of iron sulfate is 786g, and the preparation method is the same.

[0082] Comparative Example 8

[0083] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that the dispersant is stearamide, the mass of stearamide is 4.51 g, and the preparation method is the same.

[0084] Comparative Example 9

[0085] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that the additive is a mixture of magnesium oxide, chromium oxide and barium oxide, the mass of magnesium oxide is 13.51 g, the mass of chromium oxide is 1.13 g, and the mass of barium oxide is 5.63 g. The preparation method is the same.

[0086] Comparative Example 10

[0087] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that the flux is bismuth oxide, the mass of bismuth oxide is 4.95 g, and the preparation method is the same.

[0088] Comparative Example 11

[0089] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that the lubricant is magnesium stearate, the mass of magnesium stearate is 5.29 g, and the preparation method is the same.

[0090] Comparative Example 12

[0091] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that: the preparation method is different, and low-temperature sintering is performed by a gradient heating method in S3, specifically, heating from room temperature to 500°C and holding for 4 hours, then heating to 950°C and holding for 1 hour, and then heating to 1100°C and holding for 8 hours, with a heating rate of 4°C / min, and finally cooling to room temperature with the furnace to obtain manganese-zinc absorbing ferrite, and the other steps are the same.

[0092] Comparative Example 13

[0093] This comparative example provides a low-temperature sintered manganese-zinc absorbing ferrite and a preparation method thereof. The difference between this comparative example and Example 2 is that the flux is lead acetate and silver nitrate, the mass of the lead acetate is 0.45 g, the mass of the silver nitrate is 4.50 g, and the preparation method is the same.

[0094] Experimental example

[0095] The manganese-zinc absorbing ferrites prepared in Examples 1-2 and Comparative Examples 1-13 were engraved to obtain rings with an outer diameter of 76.7 mm, an inner diameter of 33.9 mm, and a height of 6.5 mm. The return loss (RL) was measured using a vector network analyzer to evaluate the material's absorbing performance. When RL < -10 dB, the material absorbed 90% of the incident electromagnetic wave energy; when RL < -20 dB, the material absorbed 99% of the incident electromagnetic wave energy. The specific test results are shown in Tables 1 and 2.

[0096] Table 1: Property test results of Example 1 and Comparative Examples 1-6

[0097]

[0098] Table 2: Property test results of Example 2 and Comparative Examples 7-12

[0099]

[0100] It can be seen from Table 1 and Table 2 that the manganese-zinc absorbing ferrite obtained by low-temperature sintering the main material, dispersant, additive, flux and lubricant selected in the present invention in a gradient temperature increase manner has good absorbing performance.

[0101] The iron phosphate in the present invention can optimize the electromagnetic wave absorption performance. The phosphorus doping adjusts the complex dielectric constant and complex magnetic permeability of the material, so that it has higher magnetic resonance and dielectric properties within a specific frequency range, thereby more effectively absorbing electromagnetic waves and converting them into heat energy, reducing the reflection and interference of electromagnetic waves.

[0102] The nano-lead acetate and nano-silver nitrate in the present invention can form grain boundaries during low-temperature sintering of ferrite, allowing the sintering to proceed in a liquid-phase sintering manner, thereby significantly promoting the transfer of substances during the sintering process, achieving low-temperature densification of the material, and improving the wave absorption performance while reducing the sintering temperature.

[0103] As can be seen from Table 2, compared with Example 2 and Comparative Example 13, the flux used in both is the same, but the particle size of the flux is different. Example 2 uses a nano-level flux, which has better dispersibility than the flux of ordinary particles. It can better form grain boundaries and refine grains during sintering, and can better reduce the sintering temperature while improving the absorption performance.

[0104] The mixture of copper oxide, calcium oxide and niobium oxide in the present invention interacts with the main material during the sintering process to occupy the gaps in the octahedral space formed by oxygen ions, promote the formation of grain boundaries, refine the grains, and improve the wave absorbing performance of the material.

[0105] The fumed alumina in the present invention can be orderly bonded to the surface of the matrix particles to form a shell layer. This shell layer effectively reduces the electrostatic attraction between the particles, avoids powder adhesion caused by van der Waals forces, moisture absorption, particle friction, etc., thereby improving the fluidity of the powder. Powder with good fluidity can be more fully filled in the mold, and high-density ferrite is obtained by pressing.

[0106] In the present invention, niobium diselenide is rapidly transformed into a liquid lubricating film due to the increase in pressure during the pressing process of ferrite powder, playing a lubricating role. The niobium element therein forms crystal nuclei during the sintering process, promotes the homogenization of the grains, reduces the sintering temperature and improves the wave absorbing performance.

[0107] The molybdenum disulfide in the present invention is a type of transition metal chalcogenide and a non-centrosymmetric material. Its high specific surface area and polymorphism give it excellent electronic properties. At the same time, the change in layer thickness caused by the quantum confinement effect can change the band gap of molybdenum disulfide, thereby achieving lubrication and improving the absorption performance.

[0108] In summary, the embodiment exhibits good wave absorbing performance while meeting the purpose of low-temperature sintering.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A low temperature sintered manganese zinc absorbing ferrite, characterized in that: Including main ingredients, flux, dispersant, additives and lubricants; The main ingredients include ferric phosphate, ferric nitrate, zinc sulfate and manganese nitrate, and the molar ratio of the ferric phosphate, ferric nitrate, zinc sulfate and manganese nitrate is 2:2:1:1; The flux is nano-lead acetate and nano-silver nitrate, wherein the nano-lead acetate accounts for 0.02-0.04% of the main material weight, and the nano-silver nitrate accounts for 0.1-0.5% of the main material weight; The additive is a mixture of copper oxide, calcium oxide and niobium oxide, wherein the copper oxide accounts for 1.1-3.3% of the main material, the calcium oxide accounts for 0.04-0.1% of the main material, and the niobium oxide accounts for 0.33-0.52% of the main material.

2. The low temperature sintered manganese zinc absorbing ferrite according to claim 1, characterized in that: The dispersant is a mixture of triammonium citrate and ammonium polymethacrylate, wherein the triammonium citrate accounts for 0.1-0.5% of the mass of the main material, and the ammonium polymethacrylate accounts for 0.1-0.5% of the mass of the main material.

3. The low temperature sintered manganese zinc absorbing ferrite according to claim 1, characterized in that: The lubricant is a mixture of fumed aluminum oxide, niobium diselenide and molybdenum disulfide, wherein the fumed aluminum oxide accounts for 0.05-0.1% of the main material mass, the niobium diselenide accounts for 0.1-0.2% of the main material mass, and the molybdenum disulfide accounts for 0.1-0.2% of the main material mass.

4. The method for preparing the low-temperature sintered manganese-zinc absorbing ferrite according to any one of claims 1 to 3, wherein: The following steps are involved: S1: placing the main material and dispersant in water, stirring, adding ammonia water to adjust the pH, heating, keeping warm, baking, and keeping warm again to obtain a powder; S2 calcining the powder, and mixing the calcined powder with flux, additives, lubricant and water by ball milling to obtain a slurry; S3 adds the slurry to the PVA solution for spray granulation, then performs bidirectional pressing, and finally uses a gradient temperature increase method to perform low-temperature sintering to obtain manganese zinc absorbing ferrite.

5. The method for preparing low temperature sintered manganese zinc absorbing ferrite according to claim 4, characterized in that: In the S1, the pH is adjusted to 6.2-8.0, the heating temperature is 80-90°C, and the baking temperature is 200-300°C.

6. The method for preparing low temperature sintered manganese zinc absorbing ferrite according to claim 4, characterized in that: In the above-mentioned S2, the calcination temperature is 900-950° C., and the calcination time is 1.5-2.0 h.

7. The method for preparing low temperature sintered manganese zinc absorbing ferrite according to claim 4, characterized in that: In S2, stainless steel balls are added during the ball milling process, and the mass of the added stainless steel balls is 4 times the mass of the main material; the ball milling time is 60-80 min, and the ball milling speed is 400-450 r / min.

8. The method for preparing low temperature sintered manganese zinc absorbing ferrite according to claim 4, characterized in that: In S2, the mass of the added water is the same as the mass of the main material.

9. The method for preparing low-temperature sintered manganese-zinc absorbing ferrite according to claim 4, characterized in that: In S3, the pressure of bidirectional pressing is 0.5-1.0t / cm 2 .

10. The method for preparing low temperature sintered manganese zinc absorbing ferrite according to claim 4, characterized in that: The gradient heating method is specifically: heating from room temperature to 120°C and keeping it for 1 hour, then heating to 400°C and keeping it for 1 hour, then heating to 500°C and keeping it for 4 hours, then heating to 950°C and keeping it for 1 hour, then heating to 1100°C and keeping it for 8 hours, and finally cooling to room temperature with the furnace. The heating rate is 3-5°C / min.

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