Preparation method and application of BaFe12O19 / BaTiO3 composite microwave absorbing material

Abstract

The invention discloses a preparation method and application of a BaFe12O19 / BaTiO3 composite microwave absorbing material, belongs to the field of solid waste utilization and microwave absorbing materials, and solves the technical problems of high-value and resource utilization of rare earth waste residues or waste gas warm paste residues. According to the solution, firstly, solid waste is subjected to ball milling, screening and drying treatment; secondly, preparing a barium acetate aqueous solution; thirdly, adding the barium acetate solution into a mixed solution prepared from tetrabutyl titanate, glacial acetic acid and absolute ethyl alcohol to prepare sol, adding the solid waste powder into the sol, magnetically stirring and uniformly mixing, and aging to obtain gel; and finally, drying the gel, and roasting at a constant temperature in an air atmosphere to prepare the BaFe12O19 / BaTiO3 composite microwave absorbing material. The composite microwave absorbing material is prepared by taking the rare earth waste residues or the waste gas warm paste residues as main raw materials, a new thought is provided for comprehensive utilization of the rare earth waste residues, and low-cost preparation of the microwave absorbing material is also realized.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste utilization and microwave absorbing materials, and specifically relates to a BaFe 12 O 19 Preparation method and application of / BaTiO3 composite microwave absorbing material. Background Art

[0002] With the rapid development of modern science and technology, communication equipment, household appliances, aerospace and other equipment have greatly facilitated human life, making human life more and more comfortable and efficient. Humans are increasingly inseparable from these electronic devices. However, electromagnetic radiation fills people's living space, causing serious electromagnetic pollution. It has become another major public hazard after noise pollution, air pollution, water pollution and solid waste pollution, thus attracting widespread attention from countries around the world. Electromagnetic pollution mainly includes two aspects: one is the damage to human life and health, and the other is the electromagnetic interference to various electronic instruments and equipment. Scientists predict that in the 21st century, electromagnetic wave pollution will become the most important physical pollution of the ecological environment. As a result, microwave absorbing materials came into being. Absorbing materials are widely used in the civilian field. For example, absorbing materials can be used as electromagnetic protection materials for mobile phones, televisions, computers, clothing, etc. to reduce the harm of electromagnetic waves to the human body; for example, as building absorbing materials, concrete materials with absorbing functions are used in the construction industry to reduce the reflection of radio waves in tall buildings and improve the quality of radio and television broadcasting; in addition, using absorbing materials in micromotors and other electronic equipment can also reduce electronic and electrical errors caused by electromagnetic interference. Therefore, the preparation of effective microwave absorbing materials has become more and more urgent. However, the production cost of microwave absorbing materials has become an important factor hindering the development of absorbing materials. Therefore, seeking an absorbing material with lower raw material prices, simpler production processes, and better product performance has become an urgent problem to be solved.

[0003] Since the birth of the third generation of rare earth permanent magnet material, NdFeB, it has been widely used due to its excellent magnetic properties, and its output and consumption have also increased day by day. However, in the production process of NdFeB magnetic materials, NdFeB waste of no less than 30% of the raw material weight will be produced, of which about 30% is rare earth, more than 60% is iron, and there is also a part of waste slag containing cobalt, aluminum, copper and other elements. This waste slag is generally called "primary waste slag". After further purification of the primary waste slag, the rare earth is extracted to obtain secondary waste slag, and the iron content in the secondary waste slag will reach 80%. At present, there are many studies on primary waste slag, mainly focusing on the enrichment and refining of rare earth in waste slag, but the utilization of secondary waste slag is less, which will cause waste of resources and environmental pollution. Therefore, the rational and efficient use of rare earth waste slag can not only alleviate environmental pressure, but also promote the healthy development of the rare earth industry.

[0004] The global demand for heating pads is increasing. Today, China has reached a daily production of 1 million pieces, and the annual sales volume in the country is about 200 million pieces. Heating pads contain polymers synthesized from iron, activated carbon, inorganic salts, water, etc. The iron powder in the raw materials varies from manufacturer to manufacturer, and the basic iron powder content is 68% to 85%. According to the idea of ​​"treating waste with waste", the used heating pads can be simply processed to extract useful substances and prepare them into microwave absorbing materials.

[0005] Barium ferrite (BaFe 12 O 19 ) is a strongly magnetic metal oxide with a strong bulk density. BaFe 12 O 19 BaFe is a magnetic powder that outperforms typical metal particles in data storage tapes and other media in terms of capacity and durability. 12 O 19 The magnetic properties of the material are not affected by heating, degradation and oxidation. It has a moderately high Curie temperature, high coercivity, high attractive anisotropy area, and excellent chemical stability and corrosion resistance, and can be used as a magnetic component with excellent performance in microwave absorption. Majid Saeedi successfully prepared nanocrystalline BaFe using Fe2O3 and BaCO3 mixed powder as raw materials, sintered after high-energy ball milling. 12 O 19 Hexaferroic ceramics. In addition, BaTiO3 has excellent ferroelectric properties, high dielectric constant and excellent piezoelectric properties, and is a typical dielectric material. However, due to some of its inherent defects (such as narrow absorption bandwidth and unsatisfactory reflection loss peak), pure BaTiO3 cannot be used as a single electromagnetic wave absorption material. Therefore, BaFe 12 O 19 As a magnetic component, the composite microwave absorbing material with BaTiO3 as a dielectric component has more excellent performance.

[0006] In summary, the rare earth waste residue and the waste heating pad residue can be reasonably recycled and utilized to prepare BaTiO3 / BaFe 12 O 19 Composite microwave absorbing materials can not only reduce the adverse impacts and waste of resources on the environment and society caused by improper handling of discarded heating pad residues, but also significantly reduce the production cost of composite microwave absorbing materials, providing a new direction for the recycling and reuse of discarded heating pad residues. Summary of the invention

[0007] The main purpose of the present invention is to overcome the deficiencies in the prior art, solve the environmental problems caused by the continuous stacking of rare earth waste residues and discarded heating pads, and avoid the waste of resources and reduce the technical problems of preparing composite absorbing materials. The present invention reasonably develops and utilizes rare earth waste residues or discarded heating pads to provide a BaFe 12 O 19 The preparation method and application of / BaTiO3 composite microwave absorbing material can truly realize the high-value utilization of rare earth waste or discarded heating pads and the low-cost production of absorbing materials.

[0008] The present invention is realized by the following technical scheme: BaTiO3 / BaFe 12 O 19 The preparation method of the composite microwave absorbing material comprises the following steps: S1. ball-milling solid waste, wherein the solid waste is rare earth waste residue or waste heating pad residue; after ball-milling, the solid waste is sieved through a standard sieve of 80-300 meshes, and the sieved solid waste powder is placed in an oven for drying at a drying temperature of 60° C. to 100° C. for a drying time of 6-10 hours, and is reserved for use in a subsequent step; S2. Prepare a barium acetate aqueous solution with a mass concentration of 15% to 45%, which will be used in the next step; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:(1-3):(3-8) to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is added dropwise to the mixed solution, wherein the volume of the barium acetate aqueous solution accounts for 10%-30% of the volume of the mixed solution, to obtain a sol; thirdly, the solid waste powder dried in step S1 is weighed and added to the sol, wherein the mass ratio of the solid waste powder to the tetrabutyl titanate in the sol is 1:(1-6), and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S4, first, the gel prepared in step S3 is placed in an oven for drying at a temperature of 60°C to 100°C for a drying time of 6 to 12 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 600°C to 1200°C for a calcination time of 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0009] Furthermore, in the step S1, the composition and mass percentage of the rare earth waste slag are: Fe2O3: 92.1%, CoO: 1.7%, SiO2: 1.3%, Al2O3: 1.0%, LOI: 3.9%; the composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%.

[0010] Furthermore, in step S3, the rotation speed of the magnetic stirring is 100-400 r / min.

[0011] Furthermore, in the step S3, the aging is carried out at room temperature, and the aging time is 10-18 hours.

[0012] BaFe prepared by the above-mentioned preparation method 12 O 19 Application of / BaTiO3 composite microwave absorbing materials in microwave absorption process.

[0013] Furthermore, the BaFe 12 O 19 The effective phase for microwave absorption in the composite microwave absorbing material of BaTiO3 is BaFe 12 O 19 and BaTiO3, and BaFe 12 O 19 As a magnetic component, BaTiO3 serves as a dielectric component.

[0014] The beneficial effects of the present invention are: 1. Fe2O3 in rare earth waste residue or waste heating pad residue participates in the reaction as an iron source, replacing the traditional inorganic or organic iron source, which not only opens up a new way to recycle rare earth waste residue or waste heating pad residue, but also realizes the low-cost production of microwave absorbing materials; 2. BaFe 12 O 19 / BaTiO3 composite microwave absorbing material, BaTiO3 as dielectric component, BaFe 12 O 19 As magnetic components, on the one hand, dielectric / magnetic composite materials have more abundant loss sources; on the other hand, BaTiO3, BaFe 12 O 19 The excellent thermal stability enables the composite microwave absorbing material to maintain microwave absorbing performance at relatively high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The BaFe prepared from rare earth waste slag as raw material in Example 112 O 19 / BaTiO3 composite microwave absorbing material microwave reflection loss curve; Figure 2 The BaFe prepared from rare earth waste slag as raw material in Example 2 12 O 19 BaFe / BaTiO3 composite microwave absorbing material 12 O 19 Raman spectrum of Figure 3 The BaFe prepared from rare earth waste slag as raw material in Example 3 12 O 19 Raman spectrum of BaTiO3 in / BaTiO3 composite microwave absorbing material; Figure 4 The BaFe prepared from rare earth waste slag as raw material in Example 4 12 O 19 X-ray diffraction spectrum of / BaTiO3 composite microwave absorbing material.

[0016] Figure 5 In Example 5, BaTiO3 / BaFe was prepared using waste heating pad residue as raw material. 12 O 19 Microwave reflection loss curve of composite microwave absorbing material; Figure 6 Example 6: BaTiO3 / BaFe 12 O 19 Raman spectrum of BaTiO3 in composite microwave absorbing materials; Figure 7 Example 7: BaTiO3 / BaFe 12 O 19 BaFe in composite microwave absorbing materials 12 O 19 Raman spectrum of Figure 8 Example 8: BaTiO3 / BaFe 12 O 19 X-ray diffraction spectrum of composite microwave absorbing material. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Example 1

[0018] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The rare earth waste residue is ball-milled, and the chemical composition and mass percentage of the rare earth waste residue are: Fe2O3: 92.1%, CoO: 1.7%, SiO2: 1.3%, Al2O3: 1.0%, LOI: 3.9%; the rare earth waste residue is ball-milled and sieved through a 150-mesh standard sieve, and the sieved rare earth waste residue powder is placed in an oven for drying at a drying temperature of 80° C. for 8 hours, and is reserved for use in the subsequent step; S2. Prepare a 37.5% barium acetate aqueous solution for later use; S3, first, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:1.4:5.2 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is added dropwise to the mixed solution, the volume of the barium acetate aqueous solution accounts for 17.4% of the volume of the mixed solution, to obtain a sol; thirdly, the rare earth waste residue powder dried in step S1 is weighed and added to the sol, the mass ratio of the rare earth waste residue powder to tetrabutyl titanate is 1:3.1, and the mixture is mixed uniformly by magnetic stirring at a speed of 200-300 r / min; finally, the gel is obtained after aging at room temperature for 12 hours; S4. First, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1000°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0019] BaFe prepared by the preparation method described in Example 1 12 O 19 Application of BaFe / BaTiO3 composite microwave absorbing materials in microwave absorption process, in which the effective phase for microwave absorption is BaFe 12 O 19 and BaTiO3, and BaFe 12 O 19 As a magnetic component, BaTiO3 serves as a dielectric component.

[0020] like Figure 1 As shown, the BaFe prepared in Example 1 12 O 19 When the / BaTiO3 composite microwave absorbing material is used in the microwave absorption process, when the coating thickness is 4.5mm, the minimum reflection loss is -15.0dB. Example 2

[0021] BaF 12 O 19The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The rare earth waste residue is ball-milled, and the chemical composition and mass percentage of the rare earth waste residue are: Fe2O3: 92.1%, CoO: 1.7%, SiO2: 1.3%, Al2O3: 1.0%, LOI: 3.9%; the rare earth waste residue is ball-milled and sieved through a 120-mesh standard sieve, and the sieved rare earth waste residue powder is placed in an oven for drying at a drying temperature of 90° C. for 8 hours, and is reserved for use in the subsequent step; S2. Prepare a 37.5% barium acetate aqueous solution for later use; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:1.4:3.5 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is added dropwise to the mixed solution, and the volume of the barium acetate aqueous solution accounts for 22.5% of the volume of the mixed solution to obtain a sol; thirdly, the rare earth waste residue powder dried in step S1 is weighed and added to the sol, and the mass ratio of the rare earth waste residue powder to tetrabutyl titanate is 1:1.6, and the mixture is mixed uniformly by magnetic stirring at a magnetic stirring speed of 100-200 r / min; finally, the gel is obtained after aging at room temperature for 10 hours; S4. First, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1100°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0022] like Figure 2 As shown, the BaFe prepared in Example 2 12 O 19 BaFe / BaTiO3 composite microwave absorbing material has a Raman spectrum 12 O 19 The characteristic peaks of barium ferrite in the product are well crystallized. Example 3

[0023] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The rare earth waste residue is ball-milled, and the chemical composition and mass percentage of the rare earth waste residue are: Fe2O3: 92.1%, CoO: 1.7%, SiO2: 1.3%, Al2O3: 1.0%, LOI: 3.9%; the rare earth waste residue is ball-milled and sieved through a 100-mesh standard sieve, and the sieved rare earth waste residue powder is placed in an oven for drying at a drying temperature of 100° C. for 8 hours, and is reserved for use in the subsequent step; S2. Prepare a 37.5% barium acetate aqueous solution for later use; S3, first, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:1:6.9 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is added dropwise to the mixed solution, the volume of the barium acetate aqueous solution accounts for 14.7% of the volume of the mixed solution, to obtain a sol; thirdly, the rare earth waste residue powder dried in step S1 is weighed and added to the sol, the mass ratio of the rare earth waste residue powder to tetrabutyl titanate is 1:4.7, and the mixture is mixed uniformly by magnetic stirring at a speed of 200-300 r / min; finally, the gel is obtained after aging at room temperature for 15 hours; S4. First, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1100°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0024] like Figure 3 As shown, the BaFe prepared in Example 3 12 O 19 / There are obvious BaTiO3 characteristic peaks in the Raman spectrum of BaTiO3 composite microwave absorbing materials, which proves that BaTiO3 with good crystallinity can be successfully prepared by the sol-gel method. Example 4

[0025] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The rare earth waste residue is ball-milled, and the chemical composition and mass percentage of the rare earth waste residue are: Fe2O3: 92.1%, CoO: 1.7%, SiO2: 1.3%, Al2O3: 1.0%, LOI: 3.9%; the rare earth waste residue is ball-milled and sieved through a 120-mesh standard sieve, and the sieved rare earth waste residue powder is placed in an oven for drying at a drying temperature of 100° C. for 8 hours, and is reserved for use in the subsequent step; S2. Prepare a 33.3% barium acetate aqueous solution for later use; S3, first, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:1.7:6.9 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is added dropwise to the mixed solution, the volume of the barium acetate aqueous solution accounts for 16.1% of the volume of the mixed solution, to obtain a sol; thirdly, the rare earth waste residue powder dried in step S1 is weighed and added to the sol, the mass ratio of the rare earth waste residue powder to tetrabutyl titanate is 1:3.1, and the mixture is mixed uniformly by magnetic stirring at a speed of 300-400 r / min; finally, the gel is obtained after aging at room temperature for 15 hours; S4, first, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 8 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1200°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0026] Depend on Figure 4 It can be seen that the BaFe prepared in Example 4 12 O 19 / BaFe 12 O 19 , BaTiO3 characteristic peaks, proving that BaFe can be successfully prepared in composite microwave absorbing materials by sol-gel method. 12 O 19 and BaTiO3. Example 5

[0027] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The waste heating pad residue is ball-milled, and the components and mass percentages of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; the waste heating pad residue is ball-milled and sieved through an 80-mesh standard sieve, and the sieved waste heating pad residue powder is placed in an oven to dry at a drying temperature of 80°C for 10 hours, and is reserved for use in the next step; S2. Prepare a 33% barium acetate aqueous solution for later use; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:1.5:5.4 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is measured and added dropwise to the mixed solution, and the volume of the barium acetate aqueous solution accounts for 25% of the volume of the mixed solution to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, and the mass ratio of the waste heating pad residue powder to tetrabutyl titanate is 1:2.7, and the mixture is mixed uniformly by magnetic stirring at a speed of 150-250 r / min; finally, the gel is obtained after aging at room temperature for 15 hours; S4, first, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 8 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1100°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0028] BaFe prepared by the preparation method described in Example 5 12 O 19 Application of BaFe / BaTiO3 composite microwave absorbing materials in microwave absorption process, in which the effective phase for microwave absorption is BaFe 12 O 19 and BaTiO3, and BaFe 12 O 19 As a magnetic component, BaTiO3 serves as a dielectric component.

[0029] like Figure 5 As shown, the BaFe prepared in Example 5 12 O 19 When the / BaTiO3 composite microwave absorbing material is used in the microwave absorption process, when the coating thickness is 4.0mm, the minimum reflection loss is -12.24dB. Example 6

[0030] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The waste heating patch residue is ball-milled, and the components and mass percentages of the waste heating patch residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; the waste heating patch residue is ball-milled and sieved through an 80-mesh standard sieve, and the sieved waste heating patch residue powder is placed in an oven to dry at a drying temperature of 90°C for 8 hours, and is reserved for use in the next step; S2. Prepare a 40% barium acetate aqueous solution for later use; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:2:6 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is measured and added dropwise to the mixed solution, the volume of the barium acetate aqueous solution accounts for 15% of the volume of the mixed solution, to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, the mass ratio of the waste heating pad residue powder to tetrabutyl titanate is 1:1.8, and the mixture is mixed uniformly by magnetic stirring at a magnetic stirring speed of 100-150 r / min; finally, the gel is obtained after aging at room temperature for 12 hours; S4, first, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 8 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1100°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0031] like Figure 6 As shown, the BaTiO3 / BaFe prepared in Example 6 12 O 19 There are obvious characteristic peaks of BaTiO3 on the Raman spectrum of the composite microwave absorbing material, which proves that BaTiO3 with good performance can be successfully prepared by the sol-gel method. Example 7

[0032] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The waste heating patch residue is ball-milled, and the components and mass percentages of the waste heating patch residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; the waste heating patch residue is ball-milled and sieved through a 150-mesh standard sieve, and the sieved waste heating patch residue powder is placed in an oven to dry at a drying temperature of 100°C for 6 hours, and is reserved for use in the next step; S2. Prepare a 37% barium acetate aqueous solution for later use; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:3:8 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is measured and added dropwise to the mixed solution, the volume of the barium acetate aqueous solution accounts for 20% of the volume of the mixed solution, to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, the mass ratio of the waste heating pad residue powder to tetrabutyl titanate is 1:2.7, and the mixture is mixed uniformly by magnetic stirring at a speed of 200-300 r / min; finally, the gel is obtained after aging at room temperature for 10 hours; S4, first, the gel prepared in step S3 is placed in an oven for drying at a temperature of 100°C for 8 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1100°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0033] like Figure 7 As shown, the BaTiO3 / BaFe prepared in Example 7 12 O 19 The Raman spectrum of the composite microwave absorbing material shows BaFe 12 O 19 The characteristic peaks of barium ferrite in the product are well crystallized. Example 8

[0034] BaF 12 O 19 The preparation method of the composite microwave absorbing material of / BaTiO3 comprises the following steps: S1. The waste heating patch residue is ball-milled, and the components and mass percentages of the waste heating patch residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; the waste heating patch residue is ball-milled and sieved through a 120-mesh standard sieve, and the sieved waste heating patch residue powder is placed in an oven to dry at a drying temperature of 85°C for 9 hours, and is reserved for use in the next step; S2. Prepare a 35% barium acetate aqueous solution for later use; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:2.5:7 to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is measured and added dropwise to the mixed solution, the volume of the barium acetate aqueous solution accounts for 18% of the volume of the mixed solution, to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, the mass ratio of the waste heating pad residue powder to tetrabutyl titanate is 1:2.7, and the mixture is mixed uniformly by magnetic stirring at a speed of 250-350 r / min; finally, the gel is obtained after aging at room temperature for 15 hours; S4. First, the gel prepared in step S3 is placed in an oven for drying at a temperature of 95°C for 8.5 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 1100°C for 2 hours; finally, the precursor dry gel is cooled to room temperature in the furnace to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

[0035] Depend on Figure 8 It can be seen that the BaTiO3 / BaFe prepared in Example 8 12 O 19 The X-ray diffraction spectrum of the composite microwave absorbing material shows BaTiO3, BaFe 12 O 19 Characteristic peaks, proving that BaTiO3 and BaFe can be successfully prepared by sol-gel method 12 O 19 .

[0036] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. BaTiO3 / BaFe 12 O 19 The method for preparing a composite microwave absorbing material is characterized in that: The following steps are involved: S1. ball-milling solid waste, wherein the solid waste is rare earth waste residue or waste heating pad residue; after ball-milling, the solid waste is sieved through a standard sieve of 80-300 meshes, and the sieved solid waste powder is placed in an oven for drying at a drying temperature of 60° C. to 100° C. for a drying time of 6-10 hours, and is reserved for use in a subsequent step; S2. Prepare a barium acetate aqueous solution with a mass concentration of 15% to 45%, which will be used in the next step; S3. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 1:(1-3):(3-8) to obtain a mixed solution; secondly, the barium acetate aqueous solution prepared in step S2 is added dropwise to the mixed solution, wherein the volume of the barium acetate aqueous solution accounts for 10%-30% of the volume of the mixed solution, to obtain a sol; thirdly, the solid waste powder dried in step S1 is weighed and added to the sol, wherein the mass ratio of the solid waste powder to the tetrabutyl titanate in the sol is 1:(1-6), and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S4. First, the gel prepared in step S3 is placed in an oven for drying at a temperature of 60°C to 100°C for a drying time of 6 to 12 hours to obtain a precursor dry gel; Then, the precursor dry gel was placed in a muffle furnace and calcined at a constant temperature in an air atmosphere at a temperature of 600°C to 1200°C for 2 hours. Finally, it was cooled to room temperature to obtain BaFe 12 O 19 / BaTiO3 composite microwave absorbing material.

2. BaFe according to claim 1 12 O 19 The preparation method of / BaTiO3 composite microwave absorbing material is characterized in that: In the step S1, the composition and mass percentage of the rare earth waste slag are: Fe2O3: 92.1%, CoO: 1.7%, SiO2: 1.3%, Al2O3: 1.0%, LOI: 3.9%; the composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%.

3. BaFe according to claim 1 12 O 19 The preparation method of / BaTiO3 composite microwave absorbing material is characterized in that: In the step S3, the rotation speed of the magnetic stirring is 100-400 r / min.

4. BaFe according to claim 1 12 O 19 The preparation method of / BaTiO3 composite microwave absorbing material is characterized in that: In the step S3, the aging is carried out at room temperature, and the aging time is 10-18 hours.

5. BaFe prepared by the preparation method as claimed in claim 1 12 O 19 Application of / BaTiO3 composite microwave absorbing materials in microwave absorption process.

6. The use according to claim 5, characterized in that: The BaFe 12 O 19 The effective phase for microwave absorption in the composite microwave absorbing material of BaTiO3 is BaFe 12 O 19 and BaTiO3, and BaFe 12 O 19 As a magnetic component, BaTiO3 serves as a dielectric component.

Images