CN115173079A - ZnFe loaded on coal gasification fine ash carbon residue 2 O 4 Nano microsphere composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a ZnFe loaded coal gasification fine ash carbon residue ₂ O ₄ Nano microsphere composite material and preparation method thereof, znFe in the composite material ₂ O ₄ The nano-microspheres are randomly adhered to the surface of the coal gasification fine ash carbon residue, and one end of a flaky structure of part of the coal gasification fine ash carbon residue is inserted into ZnFe ₂ O ₄ Nano-microspheres; the preparation method of the composite material comprises the following steps: s1: preparing coal gasification fine ash carbon residue; s2: adding the coal gasification fine ash carbon residue in the S1 into ethylene glycol, and performing ultrasonic treatment and dispersion; s3: adding zinc salt and ferric salt into the mixed solution of S2, stirring and uniformly mixing, then continuously adding polyethylene glycol 4000 and anhydrous sodium acetate, and stirring and uniformly mixing; s4: and (4) placing the mixed solution of the S3 into a reaction kettle for reaction, and washing and drying after the reaction to obtain the ultrathin wave-absorbing material. The wave-absorbing material prepared by the invention has excellent electromagnetic wave absorption performanceThe resource recycling of the solid waste of the coal gasification technology is realized.

Description

ZnFe loaded on coal gasification fine ash carbon residue 2 O 4 Nano microsphere composite material and preparation method thereof

Technical Field

The invention relates to the technical field of wave-absorbing materials, in particular to a ZnFe loaded coal gasification fine ash carbon residue ₂ O ₄ A nano microsphere composite material and a preparation method thereof.

Background

With the rapid development of electronic information industry equipment such as mobile cellular networks, high-speed processors, broadband radars, satellite communications and the like, the electromagnetic pollution and the electromagnetic interference generated by the equipment bring potential risks to the health of human beings, the operation of electronic equipment and the information security. In order to solve the problems of electromagnetic pollution and interference, the development of a low-density, thin-thickness, broadband and strong-absorption wave-absorbing material has gradually become a research hotspot.

Advances in modern coal gasification technology have recently become a key component of efficient coal utilization and cleaning technology. However, a large amount of slag is produced during coal gasification. The problem of coal gasification slag emissions is becoming more and more serious. The coal gasification slag can be divided into Fine Slag (FS) and coarse slag. Coarse slag is generally used for building materials, and FS is very limited in resource recycling due to its abundant carbon content (20% -60%). On the one hand, the stacking or landfill of FS takes up a large amount of land, causing metal pollution to soil and water. On the other hand, FS can be of high value because it has abundant carbon residue and specific surface area. The high temperature and reducing atmosphere in the coal gasification process may cause graphitization of the Residual Carbon (RC), and thus the Residual Carbon (RC) may serve as a potential microwave absorbing carbon material.

Pure carbon materials are not suitable as absorbing materials because of their poor impedance matching characteristics. Therefore, researchers have combined carbon and ferrite materials to achieve impedance and attenuation loss conditions that enhance microwave absorption. The main object of the present invention is to prepare a new composite material using Residual Carbon (RC) as a raw material.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a ZnFe loaded on coal gasification fine ash and residual carbon ₂ O ₄ The nano microsphere composite material and its preparation method, said wave-absorbing material possessesExcellent EMWA performance and realizes the resource recycling of the solid waste in the coal gasification technology.

The invention provides a ZnFe loaded coal gasification fine ash carbon residue ₂ O ₄ A nano-microsphere composite, said ZnFe ₂ O ₄ The nano-microspheres are randomly adhered to the surface of the coal gasification fine ash carbon residue, and one end of a flaky structure of part of the coal gasification fine ash carbon residue is inserted with ZnFe ₂ O ₄ In the nano microsphere.

The invention provides ZnFe loaded on the coal gasified fine ash and residual carbon ₂ O ₄ The preparation method of the nano microsphere composite material comprises the following steps:

s1: preparing coal gasification fine ash carbon residue;

s2: adding the coal gasification fine ash carbon residue in the S1 into ethylene glycol, and performing ultrasonic treatment and dispersion;

s3: adding zinc salt and ferric salt into the mixed solution of S2, stirring and mixing uniformly, then continuously adding polyethylene glycol 4000 and anhydrous sodium acetate, and stirring and mixing uniformly;

s4: and (3) placing the mixed solution of the S3 into a reaction kettle for reaction, and washing and drying after the reaction to obtain the ultrathin wave-absorbing material.

Preferably, the coal gasification fine ash carbon residue in S1 is prepared by a two-step acid leaching method.

Preferably, the mass molar ratio of the gasified fine ash carbon residue, the zinc salt, the iron salt, the polyethylene glycol 4000 and the anhydrous sodium acetate is 1g.

Preferably, the power of the ultrasonic treatment in S2 is 400-800W, and the ultrasonic treatment time is 20-40min.

Preferably, the zinc salt in S2 is one or more of zinc chloride and its hydrate, zinc nitrate and its hydrate, and zinc sulfate and its hydrate.

Preferably, the ferric salt in S2 is one or more of ferric chloride and its hydrate, ferric nitrate and its hydrate, and ferric sulfate and its hydrate.

Preferably, the reaction temperature in the S4 is 190-210 ℃ and the reaction time is 8-12h.

Preferably, the product in S4 is washed by deionized water and absolute ethyl alcohol respectively, and the washed product is dried for 10-14h at 50-70 ℃.

The invention provides ZnFe loaded on the coal gasified fine ash and residual carbon ₂ O ₄ The application of the nano microsphere composite material in wave-absorbing materials.

The invention has the beneficial technical effects that:

ZnFe of the invention ₂ O ₄ The/residual carbon (ZFO/RC) nanocomposite is made of ZnFe ₂ O ₄ The microsphere modified carbon residue is prepared by a one-step hydrothermal synthesis method, and the preparation method is simple. The ZFO/RC composite material has excellent EMWA performance and minimum Reflection Loss (RL) at 13.04GHz _min ) Is-46.33 dB, and the maximum effective absorption bandwidth (EAB, RL is less than or equal to-10 dB) reaches 2.96GHz (11.76-14.72 GHz) when the thickness is 1.48mm. CST simulation shows that the ZFO/RC composite material has excellent microwave absorption capacity in the actual radar stealth field. Therefore, the composite material is a wave-absorbing material with ultrathin EMWA capability and application prospect, and can be used for promoting the resource recycling of solid wastes in a coal gasification technology.

Drawings

In FIG. 1, (a) is XRD pattern of RC and ZFO/RC, (b) is FT-IR spectrum of RC and ZFO/RC, and (c-d) is hysteresis loop of ZFO/RC composite material;

SEM images of (a-c), (d-f) and (g-i) in FIG. 2 are ZFO/RC-1, ZFO/RC-2 and ZFO/RC-3, respectively; (j) EDX map for ZFO/RC-3;

TEM and HRTEM images of (a-c), (d-f), (g-i) in FIG. 3, ZFO/RC-1, ZFO/RC-2, ZFO/RC-3, respectively; (j) is the element map of ZFO/RC-3;

FIG. 4 is an XPS spectrum of ZFO/RC-3; (a) total spectrum, (b) C1s, (C) O1 s, (d) Fe 2p, and (e) Zn 2p.

In FIG. 5, (a-b), (c-d), (e-f) are the reflection loss curves and three-dimensional graphs of the composite materials of ZFO/RC-1, ZFO/RC-2 and ZFO/RC-3, respectively;

FIG. 6 shows the electromagnetic parameters of the composite material at 6.0-18.0 GHz; (a) ε ', (b) ε', (c) μ ', (d) μ', and (e) tan δ _ε ，(f)tanδ _μ ；

In FIG. 7, (a-c) are ZFO/RC-1 and ZFO-Kore-Kore curves for RC-2, ZFO/RC-3; (d-f) are each C of a composite material ₀ Curve α, | Zin/Z0 |;

FIG. 8 is a CTS simulation of a sample; (a) a PEC model, (b) a ZFO/RC-3 coated PEC model, (c) PEC and ZFO/RC-3 coated RCs graph.

Detailed Description

The crystal structure in the present invention was tested by an X-ray diffractometer (XRD, labX XRD-6000, shimadzu, japan) in a scattering range (2. Theta.) of 15 to 80 degrees. The composite was tested by using fourier transform infrared spectroscopy (FT-IR) Nicolet iS5 (Seymour, usa). The samples were tested at room temperature using a vibrating sample magnetometer (VSM, PPMS-9, from Quantum Design, USA) at + -3T/MH. The surface morphology, microstructure and element distribution of the sample were observed by using a field scanning electron microscope (FEI silicon 2000, FEI corporation, netherlands) and a high-resolution transmission electron microscope (JEOL-2010, japan electronics ltd., japan). An X-ray photoelectron spectroscopy (XPS) instrument, thermo Fisher Scientific inc. Escalabmk, usa, was used to analyze the surface chemistry state of ZFO/RC composites. The electromagnetic parameters of the ZFO/RC composite were obtained by a vector network analyzer (AV 3629D, CETC 41st institute, china) in the range of 2.0-18.0 GHz. Before testing, 40wt% of ZFO/RC blend material and 60wt% paraffin wax were mixed homogeneously. The ZFO/RC-paraffin composite was made in the shape of a cylindrical mold with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm.

Example 1

The invention provides ZnFe loaded on the coal gasified fine ash and residual carbon ₂ O ₄ The preparation method of the nano microsphere composite material comprises the following steps:

s1: the coal gasification fine ash carbon Residue (RC) is prepared by a two-step acid leaching method, and the specific method refers to example 1 in CN 114181663A;

s2: adding 0.6g of coal gasification fine ash carbon residue in the S1 into 50ml of glycol, and performing ultrasonic treatment at 400W for dispersion for 20min;

s3: adding 1.5mmol ZnCl into the mixed solution of S2 ₂ And 3mmol of FeCl ₃ ·6H ₂ O, after being vigorously stirred for 15min, the mixture is continuously added1.0g of polyethylene glycol 4000 and 3.6g of anhydrous sodium acetate, and stirring at 50 ℃ for 1h;

s4: and (3) placing the mixed solution of the S3 into a reaction kettle, reacting for 8 hours at 190 ℃, washing a product after the reaction by using deionized water and absolute ethyl alcohol, and drying the washed product for 10 hours at 50 ℃ to obtain the ultrathin wave-absorbing material, which is recorded as ZFO/RC-1.

Example 2

The invention provides ZnFe loaded on the coal gasified fine ash and residual carbon ₂ O ₄ The preparation method of the nano microsphere composite material comprises the following steps:

s1: adopting a two-step acid leaching method to prepare coal gasification fine ash Residual Carbon (RC), and referring to example 1 in CN 114181663A;

s2: adding 0.6g of coal gasification fine ash carbon residue in the S1 into 50ml of glycol, and performing ultrasonic treatment at 600W for dispersion for 30min;

s3: adding 2.5mmol ZnCl into the mixed solution of S2 ₂ And 5mmol of FeCl ₃ ·6H ₂ O, after vigorously stirring for 15min, continuously adding 1.0g of polyethylene glycol 4000 and 3.6g of anhydrous sodium acetate, and stirring for 1h at 50 ℃;

s4: and (3) placing the mixed solution of S3 into a reaction kettle, reacting for 10 hours at 200 ℃, washing a product after the reaction by using deionized water and absolute ethyl alcohol, and drying the washed product for 12 hours at 60 ℃ to obtain the ultrathin wave-absorbing material, which is recorded as ZFO/RC-2.

Example 3

The invention provides ZnFe loaded on the coal gasified fine ash and residual carbon ₂ O ₄ The preparation method of the nano microsphere composite material comprises the following steps:

s1: adopting a two-step acid leaching method to prepare coal gasification fine ash Residual Carbon (RC), and referring to example 1 in CN 114181663A;

s2: adding 0.6g of coal gasification fine ash carbon residue in the S1 into 50ml of glycol, and performing ultrasonic treatment at 800W for dispersion for 40min;

s3: adding 3.5mmol ZnCl into the mixed solution of S2 ₂ And 7mmol of FeCl ₃ ·6H ₂ O, after stirring vigorously for 15min, 1.0g of polyethylene glycol 4000 and 3.6g of anhydrous sodium acetate are added, andstirring for 1h at 50 ℃;

s4: and (3) placing the mixed solution of S3 in a reaction kettle, reacting for 12 hours at 210 ℃, washing a product after the reaction by using deionized water and absolute ethyl alcohol, and drying the washed product for 14 hours at 70 ℃ to obtain the ultrathin wave-absorbing material, which is recorded as ZFO/RC-3.

To study the crystal structures of RC and ZFO/RC composites, fig. 1 (a) is an XRD pattern. Eight clear characteristic peaks at 2 theta =18.1 °, 29.9 °, 35.2 °, 42.8 °, 53.1 °, 56.6 °, 62.2 °, 73.5 °, and ZnFe, respectively ₂ O ₄ The crystal faces of (111), (220), (311), (400), (422), (511), (440) and (533) are consistent, which indicates that zinc ferrite is successfully prepared in the ZFO/RC composite material. Further, two diffraction peaks at 2 θ =25.8 ° and 43.5 ° belong to the (002) and (100) crystal planes of graphite, indicating that the degree of graphitization of carbon is increased after gasification. Specifically, the strength of the (002) plane is reduced, and the (100) plane is accompanied by ZnFe ₂ O ₄ The increase in the content of microspheres disappeared. As shown in FIG. 1 (b), the functional groups of the RC and ZFO/RC composites were detected by FT-IR spectroscopy. Three ZFO/RC composite materials at 570 and 440cm ^-1 The characteristic peaks can be attributed to the stretching vibration of Fe-O and Zn-O bands, which shows that ZnFe ₂ O ₄ Successful preparation of nanospheres. 1620cm ^-1 And 1140cm ^-1 The characteristic peaks of (a) correspond to the stretching oscillations of C = C in the benzene ring and C — O of the alkoxy group in RC. Furthermore, 2930cm ^-1 Probably due to C-H vibration, and 3440cm ^-1 Then corresponds to an-OH bond.

FIG. 1 (c-d) the magnetic characteristics of the ZFO/RC composite were examined by VSM. As shown in FIG. 1 (c), the saturation magnetization (Ms) values of ZFO/RC-1, ZFO/RC-2 and ZFO/RC-3 are 22.73, 28.45 and 39.34emu/g, respectively. Ms and ZnFe ₂ O ₄ The content of the nano microspheres is related. Thus, the addition of ZFO results in a higher saturation magnetization value. Further, as shown in fig. 1 (d), the coercive force values (Hc) were approximately 5.4, 26.5, and 25.1Oe. The coercivity value is affected by various factors, such as particle surface effects, steric effects, coupling effects, and the like. Hysteresis loops indicate that the ZFO/RC composite has magnetic losses.

ZFO/RC composite material is researched by SEM and TEMMicrostructure, surface morphology and elemental distribution of the material (fig. 2 and 3). Fig. 2 (a-i) shows that ZFOs adhere to the surface of the RC in a disordered way, with a regular microsphere structure. ZnFe with the increase of the mass fraction of the iron and zinc elements in the experiment ₂ O ₄ The nano-microspheres are gradually increased in the synthesized ZFO/RC composite material. In addition, znFe in FIG. 2 (c, f, i) ₂ O ₄ The diameter of the nanospheres was about 200, 300 and 400nm, respectively. As can be seen from fig. 2 (e, h) and fig. 3 (e), some RC sheet structures are inserted into the ZFO nanospheres to form a special heterogeneous interface, which enhances the polarization of the interface, thereby facilitating the enhancement of the microwave absorption performance. As shown in FIG. 3 (c, f, i), the HRTEM image showed a lattice distance of 0.249nm to ZnFe ₂ O ₄ The (311) crystal planes of the crystal planes are identical. In addition, the residual carbon having a crystal plane distance of 0.34nm coincided with the (002) crystal plane of graphitic carbon, which is in accordance with the results obtained by X-ray diffraction. FIGS. 2 (j) and 3 (j) show the element distributions of C, O, fe and Zn in the ZFO/RC-3 hybrid material. In summary, unique multi-structural ZFO/RC composites were successfully prepared.

The ZFO/RC-3 composite was subjected to XPS testing. As shown in FIG. 4 (a), ZFO/RC-3 has carbon, oxygen, iron and zinc elements, consistent with the EDX spectrum. In fig. 4 (b), the C1s spectrum of ZFO/RC-3 is divided into five peaks at 284.75, 285.60, 285.65, 288.85, and 291.00eV, which correspond to C = C, C-O, C-OH, O = C-OH, and pi-pi, respectively. In particular, it is concerned that the pi-pi vibration effect in the aromatic functional group may cause the appearance of a specific peak at 291.00 eV. From fig. 4 (c), the O1 s spectrum is divided into three prominent peaks at 530.59, 532.10 and 533.32eV, confirming the presence of lattice oxygen, surface-absorbed oxygen and oxygen-containing groups, respectively. The spectrum of Fe 2p is shown in FIG. 4 (d). The characteristic peaks of Fe 2p3/2 at 711.39 and 713.62eV show that Fe ³⁺ In ZnFe ₂ O ₄ Respectively occupying tetrahedral and octahedral sites. In addition, the peak of Fe 2p1/2 is at 725.52eV, while the satellite peaks at 719.52 and 733.18eV further describe Fe ³⁺ In the case of (c). As shown in FIG. 4 (e), the spectrum of Zn 2p shows two strong characteristic peaks, belonging to Zn 2p1/2 and Zn 2p3/2, at 1045.14 and 1022.04eV, respectively.

To evaluate the EMWA performance of the material, different ZnFe's can be calculated ₂ O ₄ RL value for nanosphere content ZFO/RC composites. The reflection loss derived from the permittivity and permeability is (1) and (2) calculated by the following equations:

wherein Z ₀ Is the impedance of free space; c. f, d represent the speed of light, frequency and thickness of the ZFO/RC composite, respectively. Epsilon _γ (ε _γ = ε' -j ε ″) represents the complex dielectric constant, μ _γ (μ _γ And = μ' -j μ ″) represents a complex permeability.

FIG. 5 is a three-dimensional plot of the typical reflection loss curve and RL for a ZFO/RC composite to explore ZnFe ₂ O ₄ The influence of the content of the nano microspheres on the electromagnetic attenuation capability of the prepared composite material. Minimum Reflection Loss (RL) of ZFO/RC-1 and ZFO/RC-2 as shown in FIG. 5 (a, c) _min ) The values are only-13.36 dB (1.0 mm) and-17.33 dB (1.5 mm). Notably, RL of ZFO/RC-3 composites _min The value reached a pronounced absorption strength of-46.33 dB (1.48 mm) at 13.04GHz, with a maximum EAB of 2.96GHz and an ultra-thin matching thickness of 1.48mm. The EMWA performance of the ZFO/RC-3 composite material is superior to that of ZFO/RC-1 and ZFO/RC-2. Thus, znFe ₂ O ₄ The content of the nanospheres has great influence on the EMWA capability of the ultrathin carbon residue-based ZFO/RC wave-absorbing material.

As the ZFO content increased, ε' and ε "gradually decreased, as shown in FIG. 6 (a, b). The epsilon' distribution is between 14.24 and 25.28, and shows a downward trend in the whole measuring range, and shows a frequency dispersion behavior favorable for microwave energy attenuation. The ZFO/RC-3 has a suitable value of epsilon' to allow the microwaves to penetrate into the absorber under favourable conditions. Interface polarization generated by ZFO-RC interface and a large number of defects on RC surface can cause the complexing of ZFO/RC composite materialDifference in electrical constants. The permeability μ 'and μ' are in the range of 0.90-1.09 and-0.05-0.19, respectively, as shown in fig. 6 (c, d), indicating the presence of multiple resonances. With ZnFe ₂ O ₄ The increased addition amount improves the magnetic performance of the ZFO/RC composite material and generates various magnetic loss mechanisms. To further analyze the loss mechanism, tan δ was calculated from the obtained electromagnetic parameters _ε (= ε '/ε') and tan δ _μ = μ "/μ'. Notably, the ZFO/RC composites in FIG. 6 (e, f) exhibited tan δ _ε Value ratio tan delta _μ The value is high, indicating that dielectric loss is the primary mechanism for attenuation of electromagnetic wave energy.

The relaxation process contributes to the dielectric loss, which can be described by a kerr-kerr semicircle in the microwave frequency range. The correlation between ε' and ε "may be expressed as follows:

wherein epsilon _s Denotes a fixed dielectric constant,. Epsilon _∞ Representing the optical frequency permittivity, f is the frequency of the microwave, and τ is the time of polarization relaxation. Thus, ε' and ε "may be represented as follows:

from equations (4) and (5), the relationship between ε' and ε "can be derived as follows:

the Kore-Kore curves for ZFO/RC hybrids are shown in FIG. 7 (a-c). The debye relaxation process is beneficial for improving the EMWA capability of the absorber. Interfacial polarization potential of ZFO-RCResulting in dielectric loss of the ZFO/RC nanocomposite. According to previous studies, natural resonance and eddy current losses are the main causes of magnetic losses in magnetoelectric cooperative MAMs. Equations (7) and (8) show that the eddy current loss is related to the diameter d and the conductivity σ. If C is present ₀ Is constant, then the magnetic losses are only generated by eddy current losses.

C ₀ ＝μ″(μ′) ^-2 f ^-1 (8)

In FIG. 7 (d), C ₀ The values of (a) and (b) are in a downward trend, indicating that natural resonance is responsible for the magnetic loss of the ZFO/RC composite, not eddy current loss. For the evaluation of the microwave dissipation capacity, the attenuation coefficient (α) was specified as follows:

FIG. 7 (e) shows that the alpha value of ZFO/RC-1 is higher than those of ZFO/RC-2 and ZFO/RC-3 at 6.0-18.0 GHz. However, the alpha value of ZFO/RC-3 shows the best EMWA capability. Thus, the microwave absorption characteristics of ZFO/RC depend to a large extent on ZnFe ₂ O ₄ The content of (a). In addition, the wave absorbing material needs to have a perfect impedance match, which is crucial for the entry of the electromagnetic waves into the interior of the absorber. FIG. 7 (f) shows a value of | Z of 1.48mm _in /Z ₀ Figure i-f. | Z of ZFO/RC-3 _in /Z ₀ The value of | is about 1. However, the values of ZFO/RC-1 and ZFO/RC-2 are less than 0.6 and 0.8, respectively, which means that the ZFO/RC-3 composite has better impedance matching than ZFO/RC-1 and ZFO/RC-2. The ZFO/RC-3 composite exhibits excellent EMWA capability, and its impedance matching is better than other composites due to the balance between complex permittivity and permeability.

The significant EMWA properties of ZFO/RC hybrids are mainly due to the presence of these factors. First, the carbon residue can alter the dielectric parameters, which is advantageous for achieving proper impedance matching of the resulting composite. Secondly, a large number of defectsThe presence of traps and various oxygen-containing functional groups can cause dipole polarization and defect polarization, such as-OH, of the RC surface, thereby further attenuating incident microwave energy. Third, a lot of ZnFe ₂ O ₄ The nano particles are modified on the surface of RC and can cause ZnFe ₂ O ₄ A heterogeneous interface is created between the microsphere and the RC. Fourth, according to the Cao's electron hopping theory, electromagnetic energy can be absorbed by electrons, which migrate and hop to the carbon residue sheet, thereby facilitating the transfer of electromagnetic energy into heat. Fifth, microwave energy may be dissipated through multiple reflections of incident waves between nearby RC slices. Finally, znFe which is ferromagnetic ₂ O ₄ The microspheres provide natural resonance and eddy current losses to the synthetic composite material, which can further attenuate the incident waves. Table 1 shows ZnFe ₂ O ₄ The EMWA performance of the/RC composite was compared to that of a similar magnetic carbon-based composite, indicating that the ultra-thin ZFO/RC shows excellent RL capability. All in all, the ZFO/RC nanocomposite shows ultra-thin EMWA performance.

TABLE 1 EMWA Performance comparison of composites

Sample	Thickness(mm)	RL min (dB)	EAB(RL≤-10dB)	Refs.
					ZnFe 2 O 4 /polyaniline/graphene	3.29	-58.00	3.91	[1]
ZnFe 2 O 4 @C	2.00	-51.38	4.10	[2]
					RGO/MWCNTs/ZnFe 2 O 4	1.00	-22.20	2.30	[3]
ZnFe 2 O 4 @ZnO@rGO	2.00	-35.20	3.70	[4]
					ZnFe 2 O 4 @PANI-rGO	2.10	-49.99	4.32	[5
ZnFe 2 O 4 @graphene@TiO 2	2.50	-55.60	3.80	[6]
					yolk-shellZnFe 2 O 4 @C	1.40	-37.10	3.80	[7]
ZnFe 2 O 4 @C/MWCNTs	2.50	-40.65	0.97	[8]
					ZnFe 2 O 4 /RC	1.48	-46.33	2.96	This application

Wherein:

[1]Qiao,Y.,Xiao,J.P.,Jia,Q.,et al.Preparation and microwave absorption properties of ZnFe ₂ O ₄ /polyaniline/graphene oxide composite[J].Results Phys,2019,13.

[2]Huang,Y.,Xing,W.J.,Fan,J.L.,et al.Preparation and microwave absorption properties ofthe hollow ZnFe ₂ O ₄ @C composites with core-shell structure[J].J Magn Magn Mater,2020,502.

[3]Shu,R.W.,Zhang,G.Y.,Zhang,J.B.,et al.Fabrication of reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite hybrid composites as high-performance microwave absorbers[J].JAlloy Compd,2018,736:1-11.

[4]Li,F.,Zhuang,L.,Zhan,W.W.,et al.Desirable microwave absorption performance of ZnFe ₂ O ₄ @ZnO@rGO nanocomposites based on controllable permittivity andpermeability[J].Ceram Int,2020,46(13):21744-51.

[5]Zhao,X.X.,Huang,Y.,Yan,J.,et al.Excellent electromagnetic wave absorption properties of the ternary composite ZnFe ₂ O ₄ @PANI-rGO optimized by introducing covalent bonds[J].Composites Science and Technology,2021,210.

[6]Wang,Y.,Zhu,H.Y.,Chen,Y.B.,et al.Design of hollow ZnFe ₂ O ₄ microspheres@graphene decorated with TiO ₂ nanosheets as a high-performance low frequency absorber[J].Mater Chem Phys,2017,202:184-9.

[7]Li,H.Q.,Hou,Y.H.,Li,L.C.Tunable design of yolk-shell ZnFe ₂ O ₄ @Ccomposites for enhancing electromagnetic wave absorption[J].Powder Technol,2021,378:216-26.

[8]Tang,Y.T.,Yin,P.F.,Zhang,L.M.,et al.Novel carbon encapsulated zinc ferrite/MWCNTs composite:preparation and low-frequency microwave absorption investigation[J].Ceram Int,2020,46(18):28250-61.

RCS plays an important role in manufacturing stealth aircraft to avoid discovery by radar inspection systems. To evaluate the practical application of ZFO/RC in the far field, RCs values were obtained using the CST Studio Suite 2020 software. A pre-set model (180 mm) was created from a PEC (0.5 mm) and ZFO/RC composite (1.48 mm) at 13.00 GHz. The RCS value can be calculated in the following manner.

σ(dBm ² )＝10log((4πS/λ ² )|E _s /E _i |) ² (10)

Wherein σ represents the RCS value; λ represents the wavelength of the electromagnetic wave; s represents the area of the plate; e _s And E _i Corresponding to the electric field strength of the scattered wave and the incident wave, respectively. FIG. 8 shows RCS value curves and three-dimensional intensity images from-90 to 90 for PEC and ZFO/RC-3 coated PEC samples. PEC coated with ZFO/RC-3 shows maximum RCS value at-15 dBm ² On the left and right, significantly lower than the pure PEC model, thus indicating that ZFO/RC-3 can reduce the radar scattering intensity of the PEC sheet, with excellent microwave attenuation capability at all incident wave angles. The ZFO/RC composite material can be used as a promising wave-absorbing material for practical application.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. ZnFe loaded on coal gasification fine ash carbon residue ₂ O ₄ A nano-microsphere composite material, characterized in that, the ZnFe ₂ O ₄ The nano-microspheres are randomly adhered to the surface of the coal gasification fine ash carbon residue, and one end of a flaky structure of part of the coal gasification fine ash carbon residue is inserted with ZnFe ₂ O ₄ In the nano microsphere.

2. ZnFe loaded on coal gasification fine ash carbon residue according to claim 1 ₂ O ₄ The preparation method of the nano microsphere composite material is characterized by comprising the following steps:

s1: preparing coal gasification fine ash carbon residue;

s2: adding the coal gasification fine ash carbon residue in the S1 into ethylene glycol, and performing ultrasonic treatment and dispersion;

s3: adding zinc salt and ferric salt into the mixed solution of S2, stirring and mixing uniformly, then continuously adding polyethylene glycol 4000 and anhydrous sodium acetate, and stirring and mixing uniformly;

s4: and (3) placing the mixed solution of the S3 into a reaction kettle for reaction, and washing and drying after the reaction to obtain the ultrathin wave-absorbing material.

3. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano microsphere composite material is characterized in that the coal gasification fine ash carbon residue in S1 is prepared by a two-step acid leaching method.

4. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano-microsphere composite material is characterized in that the mass molar ratio of coal gasification fine ash carbon residue to zinc salt to iron salt to polyethylene glycol 4000 to anhydrous sodium acetate is 1g to 3g:4-8g。

5. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano microsphere composite material is characterized in that the ultrasonic treatment power in S2 is 400-800W, and the ultrasonic treatment time is 20-40min.

6. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano microsphere composite material is characterized in that the zinc salt in S2 is one or more of zinc chloride and hydrate thereof, zinc nitrate and hydrate thereof, and zinc sulfate and hydrate thereof.

7. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano-microsphere composite material is characterized in that the ferric salt in S2 is one or more of ferric chloride and hydrate thereof, ferric nitrate and hydrate thereof, and ferric sulfate and hydrate thereof.

8. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano microsphere composite material is characterized in that the reaction temperature in the S4 is 190-210 ℃ and the reaction time is 8-12h.

9. ZnFe-loaded coal gasification fine ash residual carbon according to claim 2 ₂ O ₄ The preparation method of the nano microsphere composite material is characterized in that the product is washed by deionized water and absolute ethyl alcohol in S4 respectively, and the washed product is dried for 10-14h at 50-70 ℃.

10. ZnFe loaded on coal gasification fine ash residual carbon according to claim 1 ₂ O ₄ The application of the nano microsphere composite material in wave-absorbing materials.

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