MgCuNiMn-o polymer particles, and preparation method and application thereof

Abstract

The application discloses MgCuNiMn-O polygranules and a preparation method and application thereof, and comprises the following steps: mixing magnesium carbonate, manganese carbonate, copper carbonate, nickel carbonate and sodium bicarbonate, uniformly performing dry ball milling to obtain a mixed powder; adding a mixed solution of an organic binder and a dilute solvent into the obtained mixed powder, performing wet ball milling to prepare a slurry; performing spray granulation on the obtained slurry to obtain spherical precursor granules; performing programmed temperature annealing treatment on the obtained spherical precursor granules in a protective atmosphere; and after cleaning and drying the obtained annealing product, the MgCuNiMn-O polygranules are obtained. The method can prepare granules with spherical morphology, multi-stage pore structure and high specific surface area through component precise regulation and a double pore-forming mechanism, effectively solves the bottleneck of uneven dispersion of multi-component materials and microstructure regulation difficulty, and the obtained product has excellent electromagnetic wave absorption performance and application potential in the wave absorption field.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials, and particularly relates to a MgCuNiMn-O polymer particle, its preparation method and application. Background Technology

[0002] Electromagnetic wave absorbing materials, as functional materials capable of converting incident electromagnetic wave energy into heat or other forms of energy for dissipation, have urgent application needs in fields such as electromagnetic compatibility, human body protection, and information security. Ideal high-performance absorbing materials must meet the comprehensive requirements of being "thin, light, wide, and strong," meaning they must possess characteristics of thinness, light weight, wide effective absorption bandwidth, and strong absorption capacity. The core lies in achieving excellent impedance matching and strong electromagnetic loss capability through material design.

[0003] Currently, common microwave absorbing materials include ferrites, metal powders, carbon-based materials, and conductive polymers. Among them, multi-component transition metal oxide materials, especially solid solutions or composite oxides formed by combining multiple magnetic and dielectric metal elements, show great development potential due to their tunable electromagnetic parameters, good thermal stability, and rich polarization loss mechanisms. However, existing technologies (such as co-precipitation, sol-gel, and traditional solid-state reaction methods) generally face the following technical bottlenecks in preparing such multi-component materials: First, it is difficult to achieve highly uniform dispersion of multiple metal ions at the microscale, which easily leads to component segregation and phase separation, resulting in non-uniform and uncontrollable electromagnetic properties; second, the prepared materials often lack finely controlled microstructures, have low specific surface areas, and underdeveloped pore structures, limiting multiple reflections and scattering of electromagnetic waves within the material, which is detrimental to improving microwave absorption performance; finally, the products are mostly irregular powders, and their poor flowability and mechanical strength bring great difficulties to coating preparation or structural integration in practical applications.

[0004] Therefore, developing a novel preparation method for multi-component metal oxide microwave absorbing materials that can achieve precise control of components, optimization of microstructure, and good application processability is of great significance for promoting the development of high-performance microwave absorbing materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide MgCuNiMn-O polymer particles, their preparation method and application.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] A method for preparing MgCuNiMn-O polymer particles includes the following steps:

[0008] (1) Magnesium carbonate, manganese carbonate, copper carbonate, nickel carbonate and sodium bicarbonate are mixed in a mass ratio of 1:1:(1-4):(1-4):1 and then dry-milled to obtain a mixed powder.

[0009] (2) Add a mixture of organic binder and diluent to the mixed powder obtained in step (1), and then wet ball mill it into a slurry;

[0010] (3) Spray granulation of the slurry obtained in step (2) to obtain spherical precursor particles;

[0011] (4) The spherical precursor particles obtained in step (3) are subjected to programmed temperature annealing under a protective atmosphere;

[0012] The temperature-heating annealing process includes three stages:

[0013] The first stage involves heating to 450-550℃ and holding at that temperature; the second stage involves heating to 900-1000℃ at a rate of 4-6℃ / min; and the third stage involves holding at 900-1000℃.

[0014] (5) The annealed product obtained in step (4) is washed and dried to obtain the MgCuNiMn-O polymer particles.

[0015] As a further improvement, the organic binder in step (2) is one of polyvinyl acetate, epoxy resin or acrylate.

[0016] As a further improvement, the dry basis mass of the organic binder in step (2) is 10%-40% of the total mass of magnesium carbonate, manganese carbonate, copper carbonate and nickel carbonate.

[0017] As a further improvement, the diluting solvent in step (2) is anhydrous ethanol, and its volume ratio with the organic binder is 2-5:1.

[0018] As a further improvement, the viscosity of the slurry obtained in step (2) is controlled at 2000-5000 mPa·s.

[0019] As a further improvement, the spray granulation in step (3) controls the inlet temperature to 150±5℃ and the outlet temperature to 90±5℃.

[0020] As a further improvement, in step (4), the first stage is to raise the temperature to 450-550℃ at a rate of 8-12℃ / min and keep it at that temperature for 4-6 hours.

[0021] As a further improvement, the third stage described in step (4) is kept at 900-1000℃ for 6-10 hours.

[0022] The present invention provides a MgCuNiMn-O polymeric particle, which is prepared by the preparation method described above.

[0023] This invention provides an application of the MgCuNiMn-O polymer particles as an electromagnetic wave absorbing material.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention achieves a significant breakthrough in the synthesis of multi-component metal oxide materials through synergistic innovation in material systems and process routes.

[0026] First, by using multiple carbonates and sodium bicarbonate as precursor systems, and combining mechanical activation-ball milling pretreatment with solution-ball milling composite pulping process, molecular-level uniform dispersion of four metal elements, Mg, Cu, Ni, and Mn, was achieved at the micron scale. This not only ensured the precise control of the composition, but also laid the structural foundation for the subsequent formation of homogeneous solid solutions or composite metal oxides, fundamentally solving the problems of component segregation and uneven distribution that are prone to occur in traditional co-precipitation or solid-phase mixing methods.

[0027] Secondly, this invention ingeniously constructs a unique dual pore-forming mechanism: the gas generated by the thermal decomposition of sodium bicarbonate forms the initial pores, while the carbonization-removal process of the organic binder constructs an interconnected network of mesopores and macropores. This multi-level pore structure significantly improves the specific surface area and pore volume of the material, providing an efficient channel for reaction mass transfer and exposing more active sites, thereby greatly enhancing the intrinsic activity of the material.

[0028] Finally, by combining spray granulation technology with a precisely controlled heat treatment process, nanoscale activity and micron-level operability were successfully combined to prepare polymer particles with spherical morphology, narrow particle size distribution and excellent mechanical strength, so that the material has both high catalytic activity and excellent industrial application performance.

[0029] These three aspects support and synergize with each other, together constituting the core innovative advantages of this invention.

[0030] The method of this invention prepares particles with spherical morphology, multi-level pore structure and high specific surface area through precise control of components and dual pore-forming mechanism. It effectively solves the bottleneck of uneven dispersion of multi-component materials and difficulty in microstructure control. The obtained product shows excellent electromagnetic wave absorption performance and application potential in the field of microwave absorption. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a low-magnification TEM image of the MgCuNiMn-O polymer particles from Example 1;

[0033] Figure 2 This is a high-magnification TEM image of the MgCuNiMn-O polymer particles from Example 1;

[0034] Figure 3 This is the selected area electron diffraction pattern of the MgCuNiMn-O polymer particles in Example 1;

[0035] Figure 4 This is a two-dimensional reflection loss spectrum of Example 1;

[0036] Figure 5 This is the two-dimensional reflection loss spectrum of Example 2;

[0037] Figure 6 This is the two-dimensional reflection loss spectrum of Example 3;

[0038] Figure 7 This is the two-dimensional reflection loss spectrum of Example 4;

[0039] Figure 8 This is a two-dimensional reflection loss spectrum for Comparative Example 1;

[0040] Figure 9 This is a two-dimensional reflection loss spectrum for Comparative Example 2;

[0041] Figure 10 This is a two-dimensional reflection loss spectrum for Comparative Example 3;

[0042] Figure 11 This is the two-dimensional reflection loss spectrum of Comparative Example 4. Detailed Implementation

[0043] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0044] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0045] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0046] In some specific embodiments, the method for preparing MgCuNiMn-O polymer particles of the present invention includes the following steps:

[0047] I. Raw material proportioning and preliminary mixing

[0048] Magnesium carbonate, manganese carbonate, copper carbonate, nickel carbonate and sodium bicarbonate are mixed in a mass ratio of 1:1:(1-4):(1-4):1 (preferably 1:1:1:1:1) and then dry-milled to obtain a mixed powder.

[0049] This preparation method begins with a precise raw material ratio and mixing process. First, the base powder is accurately weighed according to a predetermined ratio, in which magnesium carbonate, manganese carbonate, copper carbonate, nickel carbonate and sodium bicarbonate are all fixed at 1 part, while the ratio of copper carbonate to nickel carbonate can be flexibly adjusted within the range of 1 to 4 parts. For example, taking 100 grams as a standard, the elemental composition of the final product can be controlled by setting different ratios (such as Mg:Cu:Ni:Mn=1:2:3:1).

[0050] Subsequently, these powders are placed in a planetary ball mill for dry ball milling and mixing. This process uses zirconia balls with a specific ratio as the ball milling medium, with the ball-to-material ratio controlled between 5:1 and 10:1. The ball milling is carried out at a speed of 250-350 rpm for 2 to 4 hours. The core purpose is to achieve uniform mixing of all raw material powders at the micron level, laying a homogeneous foundation for subsequent reactions.

[0051] II. Adding Binders and Preparing Slurry

[0052] After the powders are uniformly mixed, the binder is added and the slurry is prepared. An organic binder (10%-40% of the total mass of the four powders—magnesium carbonate, manganese carbonate, copper carbonate, and nickel carbonate—on a dry basis) and a diluent (preferably anhydrous ethanol, with a volume ratio of 2-5:1 to the organic binder) are added to the obtained mixed powders, and the mixture is then wet-milled to form a slurry.

[0053] The organic binder is one of polyvinyl acetate, epoxy resin (e.g., commercially available low-viscosity bisphenol A epoxy resin), or acrylate. Polyvinyl acetate is preferred as the binder, with a solid content of 40-60%, and its dosage is calculated based on its dry weight accounting for 10-40% of the total mass of the aforementioned four carbonates. It is pre-diluted with anhydrous ethanol at a volume ratio of 1:(2-5). Specifically, in a continuously running ball mill, the rotation speed is reduced to approximately 150 rpm, and the diluted binder solution is slowly dripped into the mixed powder at a slow rate of 5-10 mL / min using a constant flow pump or peristaltic pump. This wet ball milling process lasts approximately 1 to 2 hours, with the ultimate goal of obtaining a slurry with uniform viscosity, good flowability, and a viscosity controlled within the range of 2000-5000 mPa·s, ensuring smooth discharge.

[0054] III. Spray granulation and pellet forming

[0055] The prepared slurry was immediately dried and shaped using spray granulation technology. The resulting slurry was then spray granulated, with the inlet temperature controlled at 150±5℃ and the outlet temperature at 90±5℃, to obtain spherical precursor particles.

[0056] This process involves centrifugal spray drying, completed within a centrifugal spray dryer. Its core process parameters are precisely set: the feed rate is controlled at approximately 500 mL / h via a peristaltic pump, and the atomizer speed is set to approximately 15,000 rpm. The inlet temperature is strictly controlled within the range of 150±5℃ to prevent premature cross-linking or decomposition of the binder; the outlet temperature is stabilized at 90±5℃ to ensure that the slurry droplets are fully dried and form spherical particles, while simultaneously allowing complete solvent evaporation. Throughout the process, the pressure differential of the cyclone separator must be maintained stable to ensure efficient collection of the granulated particles.

[0057] IV. High-Temperature Annealing and Phase Transformation

[0058] The obtained spherical precursor particles were subjected to programmed heating annealing under a protective atmosphere to achieve pyrolysis and alloying.

[0059] The collected granulated particles undergo a crucial high-temperature annealing process to achieve pyrolysis and alloying. This process is carried out in a programmable temperature-controlled furnace filled with high-purity nitrogen or argon gas. The annealing process is carefully divided into three stages: the first stage involves heating from room temperature to 450-550°C at a rate of 8-12°C / min and holding at this temperature for 4-6 hours. This stage aims to completely decompose all carbonates and sodium bicarbonate into the corresponding metal oxides and Na₂CO₃, while the binder carbonizes to form a porous carbon network. Subsequently, the second stage involves heating to the target temperature of 900-1000°C at a slower rate of 4-6°C / min. Finally, the particles are held at 900-1000°C for 6-10 hours. In this stage, under a reducing carbon environment, the metal oxides are partially reduced and form complex metal oxide solid solutions or composite oxides through solid-state diffusion, ultimately achieving "alloying" within the particles.

[0060] The second stage involves controlling the heating rate at a relatively slow pace, primarily to match the kinetics of the solid-state reaction and ensure the formation of a uniform microstructure and ideal porous morphology. Specifically, this design is based on four considerations: First, the rates of solid-state reactions and ion diffusion are much lower than those of liquid-phase or gas-phase reactions. Slow heating prevents premature sintering of the particle surface into a dense shell, which could lead to incomplete internal reactions, thus preventing component segregation and "half-cooked" phenomena, and ensuring the overall uniformity of the product. Second, the CO2 gas continuously released from carbonate decomposition needs to escape smoothly. Excessive heating can cause a sudden release of gas, leading to particle cracking or pore collapse. A rate of approximately 5°C / min is conducive to forming a uniform and fine porous structure and inhibits… Premature closure of pores at high temperatures is crucial for improving the multiple reflection and scattering efficiency of electromagnetic waves in microwave absorbing materials. Furthermore, the growth quality and size of grains directly affect material performance; slower heating can inhibit abnormal grain growth and promote the formation of fine and uniform crystals, thereby improving crystal integrity and electromagnetic wave absorption characteristics. Finally, in the high-temperature range of 500℃ to nearly 1000℃, slow heating can significantly reduce the temperature gradient, avoid internal stress and microcracks caused by thermal shock, and ensure that the material steadily completes structural reconstruction and performance optimization during thermodynamic equilibrium.

[0061] V. Post-processing and final products

[0062] The annealed particles require meticulous post-processing to improve their purity. The annealed product is washed with hot water and dried to obtain porous MgCuNiMn-O polymer particles.

[0063] The first step is washing to remove residual sodium salts and other soluble byproducts. This is done by mixing the granules with hot deionized water at 80°C at a solid-liquid ratio of 1:10, magnetically stirring for 30 minutes, and then filtering. This process is repeated four times until the filtrate meets the required standard. The washed granules are then transferred to a vacuum drying oven and dried at 80°C and a vacuum of -0.08 MPa for 6 hours to thoroughly remove moisture and prevent agglomeration.

[0064] The final product is "porous MgCuNiMn-O polymer particles", which are expected to be spherical or near-spherical in shape, with particle size mainly distributed between 10 and 80 micrometers. They have a well-developed porous structure inside, composed of metal oxide solid solution / composite oxide, and thus have high specific surface area and abundant active sites.

[0065] The formation mechanism of porous MgCuNiMn-O polymer particles prepared in this invention is a complex process involving physical mixing, thermal decomposition, in-situ reduction, and solid-state diffusion. First, micron-level uniform mixing of carbonate raw materials is achieved through high-energy ball milling, followed by spray granulation to form spherical precursors. The following key reactions occur sequentially during the heat treatment process:

[0066] A thermal decomposition reaction occurs during the heat preservation stage at 450-550℃:

[0067] MgCO3→MgO +CO2↑

[0068] MnCO3→MnO +CO2↑

[0069] CuCO3→CuO +CO2↑

[0070] NiCO3→NiO +CO2↑

[0071] 2NaHCO3→Na2CO3+H2O↑ +CO2↑

[0072] At the same time, the polyvinyl acetate binder undergoes carbonization to form an amorphous carbon network.

[0073] Carbothermic reduction reaction occurs at high temperatures of 900-1000℃:

[0074] 2CuO + C → 2Cu + CO2↑

[0075] 2NiO +C→2Ni+CO2↑

[0076] Subsequently, solid solutions and composite oxides are formed through solid-state diffusion:

[0077] xNiO + yMnO → (Ni,Mn)O

[0078] MgO + (Cu, Ni, Mn)O → MgCuNiMn-O

[0079] Finally, after washing to remove the Na2CO3 byproduct, MgCuNiMn-O polymer particles with a multi-level porous structure and a specific phase composition are obtained.

[0080] Example 1

[0081] This embodiment provides a method for preparing porous MgCuNiMn-O polymer particles.

[0082] First, the raw materials were proportioned and initially mixed. 100g of magnesium carbonate, 100g of manganese carbonate, 100g of copper carbonate, 100g of nickel carbonate, and 100g of sodium bicarbonate (in a mass ratio of 1:1:1:1:1) were weighed and placed in a planetary ball mill. Zirconia ball milling media were added, with a ball-to-material ratio of 5:1. The mixture was ball-milled at 300 rpm for 2 hours to obtain a uniform powder.

[0083] Next, the binder was added and the slurry was prepared. 400 g of polyvinyl acetate emulsion with a solid content of 40% (its dry weight is 160 g, accounting for 40% of the total mass of the four carbonates) was weighed and diluted with 800 mL of anhydrous ethanol (volume ratio 1:2). In a continuously running ball mill, the rotation speed was reduced to 150 rpm, and the diluted binder solution was slowly added dropwise to the mixed powder at a rate of 5 mL / min using a peristaltic pump. After the addition was complete, ball milling continued for 1 hour to obtain a homogeneous slurry with a viscosity of approximately 3000 mPa·s.

[0084] Then, spray granulation and particle forming are performed. The above slurry is granulated by a centrifugal spray dryer, with the feed rate controlled at 500 mL / h, the atomizer speed at 15,000 rpm, the inlet temperature at 150℃, and the outlet temperature at 90℃, and spherical precursor particles are collected.

[0085] Afterward, high-temperature annealing and phase transformation were performed. The precursor particles were placed in a tube furnace and heat-treated under argon protection: the temperature was increased to 500℃ at 10℃ / min and held for 5 hours; then the temperature was increased to 900℃ at 5℃ / min and held for 8 hours; and then cooled in the furnace.

[0086] Finally, post-processing was performed. The annealed particles were mixed with hot deionized water at 80°C at a solid-liquid ratio of 1:10, magnetically stirred for 30 minutes, filtered, and washed four times. The washed particles were then dried in a vacuum drying oven at 80°C and -0.08 MPa for 6 hours to obtain the final product, porous MgCuNiMn-O polymer particles.

[0087] Example 2

[0088] The difference between this embodiment and Embodiment 1 is that:

[0089] The raw material ratio was adjusted to: 100g magnesium carbonate, 100g manganese carbonate, 200g copper carbonate, 100g nickel carbonate, and 100g sodium bicarbonate (i.e., a mass ratio of 1:1:2:1:1). The ball-to-material ratio for dry ball milling was 8:1, and the milling time was 3 hours.

[0090] The binder addition amount was: 500 g of polyvinyl acetate emulsion with a solid content of 40% (200 g dry weight, accounting for 40% of the total mass of the four carbonates), and 1000 mL of anhydrous ethanol for dilution. During wet ball milling, the binder solution drop rate was 8 mL / min, the ball milling time was 1.5 hours, and the viscosity of the resulting slurry was approximately 4000 mPa·s.

[0091] The inlet temperature of the spray granulation is 155℃, and the outlet temperature is 92℃.

[0092] High-temperature annealing was carried out in a box furnace under nitrogen protection. In the second stage, the temperature was raised to 950°C and held for 8 hours.

[0093] Example 3

[0094] The difference between this embodiment and Embodiment 1 is that:

[0095] The raw material ratio was adjusted to: 100g magnesium carbonate, 100g manganese carbonate, 100g copper carbonate, 300g nickel carbonate, and 100g sodium bicarbonate (i.e., a mass ratio of 1:1:1:3:1). The ball-to-material ratio for dry ball milling was 10:1, and the milling time was 4 hours.

[0096] The binder was replaced with 75 grams of low-viscosity bisphenol A epoxy resin (commercially available) (accounting for 12.5% ​​of the total mass of the four carbonates), and diluted with 225 ml of anhydrous ethanol (volume ratio 1:3). During wet ball milling, the binder solution was added dropwise at a rate of 10 mL / min using a constant flow pump, and the ball milling time was 2 hours. The viscosity of the resulting slurry was approximately 4500 mPa·s.

[0097] The inlet temperature of the spray granulation is 145℃, and the outlet temperature is 88℃.

[0098] The second stage of high-temperature annealing involves heating to 1000℃ and holding at that temperature for 8 hours.

[0099] Example 4

[0100] The difference between this embodiment and Embodiment 1 is that:

[0101] The raw material ratio was adjusted to: 100g magnesium carbonate, 100g manganese carbonate, 400g copper carbonate, 400g nickel carbonate, and 100g sodium bicarbonate (i.e., a mass ratio of 1:1:4:4:1). The ball-to-material ratio for dry ball milling was 7:1, and the milling time was 3.5 hours.

[0102] The binder was replaced with 625 g of acrylate emulsion with a solid content of 40% (250 g dry weight, accounting for 25% of the total mass of the four carbonates), and 1250 mL of anhydrous ethanol was used for dilution. During wet ball milling, the binder solution drop rate was 7 mL / min, the ball milling time was 1.5 hours, and the viscosity of the resulting slurry was approximately 5000 mPa·s.

[0103] High-temperature annealing was carried out in a box furnace under nitrogen protection. In the second stage, the temperature was raised to 1000℃ and held for 10 hours.

[0104] These four embodiments, through systematic adjustments to raw material ratios, binder systems, and heat treatment processes, aim to explore the directional regulatory effects of different factors on the structure and properties of porous MgCuNiMn-O polymer particles. The logic behind these changes revolves around three main aspects: First, by altering the Cu / Ni ratio (from 1:1 to 2:1 or 1:3), the intrinsic electromagnetic properties of the material are controlled. High Cu content aims to enhance dielectric polarization loss, while high Ni content tends to introduce magnetic loss mechanisms, achieving different dielectric-magnetic synergistic effects. Second, the type and amount of binder directly determine the characteristics of the precursor slurry and the porous structure after high-temperature decomposition. The aim is to optimize multiple reflections of electromagnetic waves and interfacial polarization loss by adjusting pore volume, pore size, and possible residual carbon content. Finally, increasing the final annealing temperature (from 900℃ to 1000℃) and extending the holding time (from 8 hours to 10 hours) promotes complete solid-phase reaction, crystal phase purification, and moderate grain growth under the highly active component system, thereby balancing the material's crystallinity, stability, and electromagnetic parameters. All these coordinated changes in parameters ultimately aim to optimize the impedance matching and electromagnetic wave attenuation capabilities of materials as microwave absorbing materials by precisely controlling their chemical composition, porous morphology, and microstructure.

[0105] Comparative Example 1 (used to compare the effect of adhesive type)

[0106] The only difference between this comparative example and Example 1 is that the binder is replaced with 160 grams of low-viscosity bisphenol A epoxy resin (commercially available) (which accounts for 40% of the total mass of the four carbonates of 400 grams), and the dilution is done with 480 ml of anhydrous ethanol (volume ratio 1:3).

[0107] Analysis of a single variable factor: The only difference between this comparative example and Example 1 is the type of binder (changed from polyvinyl acetate emulsion to low-viscosity bisphenol A epoxy resin). The raw material ratios, ball milling parameters, spray granulation conditions, and high-temperature annealing regime are identical to those in Example 1. This comparison can be used to investigate the influence of binder type on precursor particle formation, slurry rheology, and the pore structure of the final product.

[0108] Comparative Example 2 (used to compare the effect of annealing temperature)

[0109] The only difference between this comparative example and Example 1 is that in the high-temperature annealing process, the second stage temperature is raised to 800°C (instead of 900°C) and held for 8 hours, while the rest of the heating procedures and parameters are the same as in Example 1.

[0110] Analysis of a single variable factor: The only difference between this comparative example and Example 1 is that the final annealing temperature was reduced by 100°C. This comparison can be used to directly demonstrate the importance of the 900°C annealing temperature selected in Example 1 for forming the target crystalline phase and obtaining the desired specific surface area and porosity. Temperatures that are too low may lead to incomplete decomposition or insufficient crystallinity.

[0111] Comparative Example 3 (used to compare the effect of Cu / Ni ratio)

[0112] The only difference between this comparative example and Example 1 is that the raw material ratio is adjusted to: 100g magnesium carbonate, 100g manganese carbonate, 50g copper carbonate, 150g nickel carbonate and 100g sodium bicarbonate (i.e., the mass ratio is 1:1:0.5:1.5:1).

[0113] Analysis of a single variable: The only difference between this comparative example and Example 1 is the ratio of Cu to Ni (adjusted from 1:1 to 1:3, with the total mass remaining unchanged). The binder system, ball milling parameters, spray granulation conditions, and high-temperature annealing regime are completely identical to those in Example 1. This comparison can be used to study the effect of the transition metal Cu / Ni ratio on the electrochemical performance (such as catalytic activity and specific capacity) or gas-sensing performance of the product, excluding interference from other process variables.

[0114] Comparative Example 4 (Effect of Heating Rate)

[0115] The only difference from Example 1 is that the second stage of the annealing process is heated at a faster rate (10°C / min).

[0116] The differences between the examples and the comparative examples are shown in Table 1.

[0117]

[0118] Figure 1 This is a low-magnification TEM image of MgCuNiMn-O polymer particles. It indicates that the product is in granular form. Figure 2 This is a high-magnification TEM image of MgCuNiMn-O polymer particles, showing that the large particles are composed of numerous nanocrystals with gaps between them. The particles are granular with many internal gaps. Figure 3 The selected area electron diffraction pattern of the MgCuNiMn-O polymer particles indicates that they have a crystal structure.

[0119] The samples from the examples and comparative examples were pressed into coaxial rings (the thickness of each sample was 2.2 mm), and their electromagnetic parameters were tested using a vector network analyzer. The reflection loss (RL) value was then calculated based on the electromagnetic parameters.

[0120] Figure 4 This is a two-dimensional reflection loss spectrum of Example 1; it shows that the effective bandwidth (frequency range with RL ≤ -10dB) of the MgCuNiMn-O polymer particles is 7.3GHz, and the lowest RL value is -52dB, exhibiting excellent microwave absorption performance.

[0121] Figure 5 This is the two-dimensional reflection loss spectrum of Example 2; the effective bandwidth is 4.8 GHz, and the lowest RL value is -35.3 dB.

[0122] Figure 6 This is the two-dimensional reflection loss spectrum of Example 3; the effective bandwidth is 2.4 GHz, and the lowest RL value is -19.4 dB. Compared with Example 1, its performance is reduced because the control of the Cu / Ni ratio is very important in the MgCuNiMn-O polymer particle system. When the nickel content exceeds the optimal balance point, the material degrades in two core dimensions: impedance matching (waves are difficult to "enter") and attenuation capability (after entering, they are difficult to be "consumed"), which ultimately manifests as a weakening of the absorption peak intensity, a narrowing of the effective bandwidth, and a decrease in overall performance.

[0123] Figure 7 This is the two-dimensional reflection loss spectrum of Example 4; the effective bandwidth is 3.5 GHz, and the lowest RL value is -30.7 dB.

[0124] Figure 8 This is a two-dimensional reflection loss spectrum for Comparative Example 1; the effective bandwidth is 6.6 GHz, and the lowest RL value is -41.2 dB.

[0125] Figure 9 This is a two-dimensional reflection loss spectrum for Comparative Example 2; the effective bandwidth is 4.5 GHz, and the lowest RL value is -32.2 dB.

[0126] Figure 10 This is the two-dimensional reflection loss spectrum of Comparative Example 3, where microwave absorption performance can be ignored.

[0127] Figure 11 This is the two-dimensional reflection loss spectrum of Comparative Example 4, where microwave absorption performance can be ignored.

[0128] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing MgCuNiMn-O polymeric particles, characterized in that, Includes the following steps: (1) Magnesium carbonate, manganese carbonate, copper carbonate, nickel carbonate and sodium bicarbonate are mixed in a mass ratio of 1:1:(1-4):(1-4):1 and then dry-milled to obtain a mixed powder. (2) Add a mixture of organic binder and diluent to the mixed powder obtained in step (1), and then wet ball mill it into a slurry; the organic binder is one of polyvinyl acetate, epoxy resin or acrylate. (3) Spray granulation of the slurry obtained in step (2) to obtain spherical precursor particles; (4) The spherical precursor particles obtained in step (3) are subjected to programmed temperature annealing under a protective atmosphere; The temperature-heating annealing process includes three stages: The first stage involves heating to 450-550℃ and holding at that temperature; the second stage involves heating to 900-1000℃ at a rate of 4-6℃ / min; and the third stage involves holding at 900-1000℃. (5) The annealed product obtained in step (4) is washed and dried to obtain the MgCuNiMn-O polymer particles; The MgCuNiMn-O polymer particles are used as electromagnetic wave absorbing materials.

2. The method for preparing MgCuNiMn-O polymeric particles according to claim 1, characterized in that, The dry basis mass of the organic binder in step (2) is 10%-40% of the total mass of magnesium carbonate, manganese carbonate, copper carbonate and nickel carbonate.

3. The method for preparing MgCuNiMn-O polymeric particles according to claim 1, characterized in that, The diluting solvent in step (2) is anhydrous ethanol, and its volume ratio with the organic binder is 2-5:

1.

4. The method for preparing MgCuNiMn-O polymeric particles according to claim 1, characterized in that, The viscosity of the slurry obtained in step (2) is controlled at 2000-5000 mPa·s.

5. The method for preparing MgCuNiMn-O polymer particles according to claim 1, characterized in that, In step (3), the spray granulation process controls the inlet temperature to be 150±5℃ and the outlet temperature to be 90±5℃.

6. The method for preparing MgCuNiMn-O polymeric particles according to claim 1, characterized in that, Step (4) The first stage is to raise the temperature to 450-550℃ at a rate of 8-12℃ / min and keep it at that temperature for 4-6 hours.

7. The method for preparing MgCuNiMn-O polymeric particles according to claim 1, characterized in that, The third stage described in step (4) involves keeping the temperature at 900-1000℃ for 6-10 hours.

8. A MgCuNiMn-O polymeric particle, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 7.

9. An application of the MgCuNiMn-O polymer particles according to claim 8, characterized in that, It is used as an electromagnetic wave absorbing material.

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