FeSiAlGd wave-absorbing material and preparation method thereof

Abstract

The application provides a FeSiAlGd wave-absorbing material and a preparation method thereof, and relates to the technical field of microwave absorbing materials. x Si 29.6 Al 5.4 Gd y , wherein 57 < x < 65 and 0 < y < 8; the wave-absorbing material of the composition can absorb electromagnetic waves in a 2-18GHz microwave band, has a wide effective absorption band, high absorption efficiency (more than 90%), and excellent thermal stability; meanwhile, the application provides a preparation method of the FeSiAlGd wave-absorbing material, which can obtain the wave-absorbing material through arc melting, heat treatment and ball milling, and the synthesis process is simple and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, specifically to a FeSiAlGd microwave absorbing material and its preparation method. Background Technology

[0002] With the development of modern science and technology, various electronic and electrical devices have brought high efficiency to social production and great convenience to people's daily lives. On the other hand, the electromagnetic radiation generated by the widespread application of electromagnetic waves in science and technology has also brought new social problems. It has become a new source of pollution that is highly harmful and difficult to prevent, following water sources, air, and noise. Electromagnetic radiation not only affects normal communication but also directly endangers human health, becoming a hot issue of concern to society and the scientific community. In addition, electromagnetic radiation can also have adverse effects on electronic equipment. For example, high-frequency equipment, especially high-power high-frequency equipment, outputs a lot of power during operation, generating very strong high-frequency radiation, which can seriously interfere with other electronic equipment, instruments, and communication signals in the vicinity, and may even cause them to malfunction, leading to serious consequences.

[0003] To address the aforementioned issues, the research and development of electromagnetic wave absorbing materials with excellent absorption capabilities has become a current research hotspot. Currently, novel absorbing materials need to meet characteristics such as being thin, lightweight, wide-bandwidth, and strong, while future absorbing materials should meet even higher requirements, including multispectral stealth, environmental adaptability, high-temperature resistance, resistance to marine climates, nuclear radiation resistance, and impact resistance. Current research on absorbing materials mainly focuses on ferrites and magnetic metals. Ferrites are ferromagnetic materials, but their low saturation magnetization and low Curie temperature limit their application in high-temperature environments. Magnetic metal absorbing materials have strong conductivity, with both magnetic and dielectric losses exceeding those of ferrites. Compared to ferrites, magnetic metal absorbers offer advantages such as high saturation magnetization, high permeability, strong electromagnetic wave attenuation, and simple fabrication processes. Therefore, magnetic metals hold promise as a type of absorbing material with strong wave absorption capabilities.

[0004] By adjusting the morphology and crystal structure of sheet-like metal powders, the microwave electromagnetic parameters of composite materials can be modified to achieve better absorption effects and meet the requirements of effective absorption bandwidth, thin thickness, strong absorption performance, and light weight. Unlike transition elements such as Fe, Co, and Ni, rare earth elements possess excellent paramagnetic susceptibility, saturation magnetization, magnetocrystalline anisotropy, and magnetostriction. Therefore, adjusting and optimizing the electromagnetic parameters of microwave absorbing materials using the characteristics of rare earth elements can significantly improve their absorption performance. Developing high-performance, low-frequency rare earth magnetic microwave absorbing materials and expanding the application fields and value of rare earth elements is of great significance to my country's communications field and national security. However, the absorption bandwidth of existing rare earth magnetic microwave absorbing materials is relatively narrow, and the absorption efficiency needs to be improved. Summary of the Invention

[0005] This invention provides a FeSiAlGd microwave absorbing material and its preparation method. The microwave absorbing material has a wide absorption bandwidth, high absorption efficiency, good thermal stability and oxidation resistance.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A FeSiAlGd microwave absorbing material with the molecular formula Fe x Si 29.6 Al 5.4 Gd y , where 57<x≤65, 0≤y≤8.

[0008] The preferred molecular formula of the FeSiAlGd absorbing material is Fe. (57～63) Si 29.6 Al 5.4 Gd (2～8) Fe is preferred. (57～61) Si 29.6 Al 5.4 Gd (4～8) The optimal choice is Fe. 57 Si 29.6 Al 5.4 Gd6.

[0009] A method for preparing FeSiAlGd microwave absorbing material includes the following steps:

[0010] (1) Weigh the metal iron, silicon, aluminum and gadolinium in proportion and perform electric arc melting in a non-consumable vacuum electric arc furnace to obtain metal ingots for later use;

[0011] (2) The above metal ingots are heat-treated and then coarsely crushed to obtain metal powder;

[0012] (3) The above metal powder was ball-milled to obtain FeSiAlGd microwave absorbing material.

[0013] Preferably, the metallic iron, silicon, aluminum and gadolinium are elemental metals, and the purity of the metallic iron, silicon, aluminum and gadolinium is preferably 99.9%, more preferably 99.99%.

[0014] Preferably, the vacuum degree during the melting process is less than 3 x 10. -3 Pa.

[0015] Preferably, the metal ingot is repeatedly turned and melted 3-4 times during the smelting process.

[0016] Preferably, the melting loss rate of the smelted metal ingot is less than 1 wt.%.

[0017] The heat treatment temperature is preferably 800℃, and the time is preferably 3-6 days, more preferably 4 days, after which a metal ingot is obtained.

[0018] Preferably, before heat treatment, the metal ingot is sealed in a tube, and the working vacuum degree of the sealing tube is preferably 1 to 5 x 10. -1 Pa, more preferably 1 to 2 × 10 -1 Pa, the optimal value is 1 x 10 -1 Pa.

[0019] Preferably, the coarsely crushed powder passes through a 100-mesh sieve.

[0020] The preferred mass ratio of the coarsely crushed powder weighed before ball milling to the zirconium oxide balls is 10-16:1, more preferably 14-15:1, and most preferably 15:1.

[0021] Preferably, the mass ratio of the weighed zirconia balls is Φ8:Φ5:Φ3 = 2:5:3.

[0022] Preferably, the ball milling speed in step (3) is 260-360 r / min, more preferably 290-320 r / min, and most preferably 300 r / min.

[0023] Preferably, the ball milling time in step (3) is 20 hours.

[0024] This invention provides a FeSiAlGd microwave absorbing material and its preparation method, which has the following advantages compared with the prior art:

[0025] (1) The alloy powder prepared by this invention is rich in a large number of thin-film structures, which greatly extends the reflection path of electromagnetic waves and is beneficial for attenuation. The thin-film structure easily forms a conductive network, increasing the conductivity loss. Secondly, due to the defects of complex structure and multiple relaxation polarization, the electromagnetic wave attenuation capability is increased. Thirdly, natural resonance and exchange resonance jointly deplete electromagnetic waves at the resonant frequency. Finally, better impedance matching performance can be obtained, and better microwave absorption performance can be obtained in the corresponding frequency band.

[0026] Gd doping causes lattice distortion. When metallic impurity atoms occupy the positions of atoms in the original unit cell in a substitutional manner, it disrupts the long-range order and symmetry of the original unit cell, thereby causing defects or distortions and producing defect polarization. On the other hand, Gd doping increases the grain size. Larger grains are easier to form conductive networks, thus reducing the resistivity of the material and improving its electrical loss capability. As the doping concentration increases, the conductivity of the alloy powder increases, resulting in a larger current and stronger electrical loss capability.

[0027] Doping with Gd can significantly alter the magnetocrystalline anisotropy field and diffusion activation energy of magnetic absorbing materials, increasing both their natural resonance absorption peak and domain wall resonance absorption peak, while also giving the absorbing materials a wider absorption bandwidth. The absorbing materials obtained by doping with Gd can absorb electromagnetic waves in the 2-18 GHz microwave band, with a wide absorption bandwidth (the bandwidth of the alloy powder of this invention is >1.2 GHz in R<-10 dB), high absorption efficiency (>90%), and good thermal stability.

[0028] (2) The present invention provides a method for preparing the FeSiAlGd microwave absorbing material. The microwave absorbing material can be obtained by melting, heat treatment and ball milling. The preparation process is simple and suitable for large-scale production. Attached image description:

[0029] Figure 1 The reflectivity loss diagrams of the FeSiAlGd absorbing materials prepared in Examples 1-4 and Comparative Example 1 of this invention are shown when the thickness is 3.0 mm.

[0030] Figure 2 Fe prepared as Comparative Example 1 of this invention 65 Si 29.6 Al 5.4 Reflectance loss of absorbing material at different simulated thicknesses;

[0031] Figure 3 Fe prepared in Example 1 of this invention 63 Si 29.6 Al 5.4 Reflectance loss diagram of Gd2 absorbing material at different simulated thicknesses;

[0032] Figure 4 Fe prepared in Example 2 of this invention 61 Si 29.6 Al 5.4 Reflectance loss diagram of Gd4 absorbing material at different simulated thicknesses;

[0033] Figure 5 Fe prepared in Example 3 of this invention 59 Si 29.6 Al 5.4 Reflectivity loss diagram of Gd6 absorbing material at different simulated thicknesses.

[0034] Figure 6 Fe prepared in Example 4 of this invention 67 Si 29.6 Al 5.4 Reflectivity loss diagram of Gd8 absorbing material at different simulated thicknesses. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example 1:

[0037] Preparation of Fe 63 Si 29.6 Al 5.4 Gd2 magnetic absorbing material:

[0038] (1) According to the molecular formula Fe 63 Si 29.6 Al 5.4 2.1944g of 99.99% pure metallic iron, 0.5185g of silicon, 0.0888g of aluminum, and 0.1917g of gadolinium were weighed out and placed in a non-consumable vacuum melting furnace for melting, with the furnace vacuum reaching 3.0 x 10. -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated 4 times to obtain a metal ingot.

[0039] (2) The metal ingot is placed in a quartz tube and vacuumed, then the tube is sealed. The resulting quartz tube is placed in a muffle furnace and heat-treated at 800°C for 4 days to obtain the heat-treated metal ingot.

[0040] (3) The heat-treated metal ingot is coarsely crushed and ground until it can pass through a 100-mesh sieve. The sieved powder and zirconia balls are weighed at a mass ratio of 15:1 and placed in a ball mill jar. The mass ratio of the zirconia balls is Φ8:Φ5:Φ3 = 2:5:3. Anhydrous ethanol is added until the zirconia balls are submerged by 2-3 cm. The mixture is ball-milled at 300 r / min for 20 h. The resulting alloy microwave absorbing material is denoted as Fe. 63 Si 29.6 Al 5.4 Gd2.

[0041] Example 2:

[0042] Preparation of Fe 61 Si 29.6 Al 5.4 Gd4 magnetic absorbing material

[0043] (1) According to the molecular formula Fe 61 Si 29.6 Al 5.42.0388g of 99.99% pure metallic iron, 0.4975g of silicon, 0.0872g of aluminum, and 0.3765g of gadolinium were weighed out and melted in a non-consumable vacuum melting furnace with a furnace vacuum of 3.0 x 10. -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated 4 times to obtain a metal ingot.

[0044] (2) The metal ingot is placed in a quartz tube and vacuumed, then the tube is sealed. The resulting quartz tube is placed in a muffle furnace and heat-treated at 800°C for 4 days to obtain the heat-treated metal ingot.

[0045] (3) The heat-treated metal ingot is coarsely crushed and ground until it can pass through a 100-mesh sieve. The sieved powder and zirconia balls are weighed at a mass ratio of 15:1 and placed in a ball mill jar. The mass ratio of the zirconia balls is Φ8:Φ5:Φ3 = 2:5:3. Anhydrous ethanol is added until the zirconia balls are submerged by 2-3 cm. The mixture is ball-milled at 300 r / min for 20 h. The resulting alloy microwave absorbing material is denoted as Fe. 61 Si 29.6 Al 5.4 Gd4.

[0046] Example 3:

[0047] Preparation of Fe 59 Si 29.6 Al 5.4 Gd6 magnetic absorbing material

[0048] (1) According to the molecular formula Fe 59 Si 29.6 Al 5.4 1.8953g of 99.99% pure metallic iron, 0.4782g of silicon, 0.0838g of aluminum, and 0.5427g of gadolinium were weighed out and melted in a non-consumable vacuum melting furnace with a furnace vacuum of 3.0 x 10. -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated 4 times to obtain a metal ingot.

[0049] (2) The metal ingot is placed in a quartz tube and vacuumed, then the tube is sealed. The resulting quartz tube is placed in a muffle furnace and heat-treated at 800°C for 4 days to obtain the heat-treated metal ingot.

[0050] (3) The heat-treated metal ingot is coarsely crushed and ground until it can pass through a 100-mesh sieve. The sieved powder and zirconia balls are weighed at a mass ratio of 15:1 and placed in a ball mill jar. The mass ratio of the zirconia balls is Φ8:Φ5:Φ3 = 2:5:3. Anhydrous ethanol is added until the zirconia balls are submerged by 2-3 cm. The mixture is ball-milled at 300 r / min for 20 h. The resulting alloy microwave absorbing material is denoted as Fe. 59 Si 29.6 Al 5.4 Gd6.

[0051] Example 4:

[0052] Preparation of Fe 57 Si 29.6 Al 5.4 Gd8 magnetic absorbing material

[0053] (1) According to the molecular formula Fe 57 Si 29.6 Al 5.4 Gd8 was weighed out as follows: 1.7625g of 99.99% pure metallic iron, 0.4603g of silicon, 0.0807g of aluminum, and 0.6965g of gadolinium. The metals were placed in a non-consumable vacuum melting furnace for melting, with the furnace vacuum reaching 3.0 x 10. -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated 4 times to obtain a metal ingot.

[0054] (2) The metal ingot is placed in a quartz tube and vacuumed, then the tube is sealed. The resulting quartz tube is placed in a muffle furnace and heat-treated at 800°C for 4 days to obtain the heat-treated metal ingot.

[0055] (3) The heat-treated metal ingot is coarsely crushed and ground until it can pass through a 100-mesh sieve. The sieved powder and zirconia balls are weighed at a mass ratio of 15:1 and placed in a ball mill jar. The mass ratio of the zirconia balls is Φ8:Φ5:Φ3 = 2:5:3. Anhydrous ethanol is added until the zirconia balls are submerged by 2-3 cm. The mixture is ball-milled at 300 r / min for 20 h. The resulting alloy microwave absorbing material is denoted as Fe. 57 Si 29.6 Al 5.4 Gd8.

[0056] Comparative Example 1:

[0057] Preparation of Fe 65 Si 29.6 Al 5.4 Magnetic absorbing materials

[0058] (1) According to the molecular formula Fe 65 Si 29.6 Al5.4 Weigh out 2.3638g of metallic iron (99.99% purity), 0.5413g of silicon, and 0.0949g of aluminum. Place the metals into a non-consumable vacuum melting furnace for melting, with the furnace vacuum reaching 3.0 x 10. -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated 4 times to obtain a metal ingot.

[0059] (2) The metal ingot is placed in a quartz tube and vacuumed, then the tube is sealed. The resulting quartz tube is placed in a muffle furnace and heat-treated at 800°C for 4 days to obtain the heat-treated metal ingot.

[0060] (3) The heat-treated metal ingot is coarsely crushed and ground until it can pass through a 100-mesh sieve. The sieved powder and zirconia balls are weighed at a mass ratio of 15:1 and placed in a ball mill jar. The mass ratio of the zirconia balls is Φ8:Φ5:Φ3 = 2:5:3. Anhydrous ethanol is added until the zirconia balls are submerged by 2-3 cm. The mixture is ball-milled at 300 r / min for 20 h. The resulting alloy microwave absorbing material is denoted as Fe. 65 Si 29.6 Al 5.4 .

[0061] Performance testing

[0062] 1. The reflectivity of the alloy absorbing materials prepared in Examples 1-4 and Comparative Example 1 was measured:

[0063] Measurement method: A coaxial sample with an outer diameter of 7 mm and an inner diameter of 3 mm, and a thickness of 2.5–3.5 mm, was prepared by mixing powder (alloy absorbing material) and paraffin wax in a mass ratio of 3:1. The complex permeability and complex permittivity of the sample in the 2–18 GHz frequency band were measured using an HP8755ES microwave vector network analyzer. The reflectivity R of the single-layer absorbing material was then calculated using the following formula:

[0064]

[0065] In the formula, ε r μ r d and d represent the relative permittivity, relative permeability, and thickness of the absorbing material, respectively; f is the frequency of the electromagnetic wave; c is the propagation speed of the electromagnetic wave in a vacuum (i.e., the speed of light); and j is the imaginary unit.

[0066] When testing the reflectivity of the alloy absorbing materials prepared in Examples 1-4 and Comparative Example 1:

[0067] A. For the Fe prepared in Comparative Example 1 65 Si 29.6 Al 5.4The results of calculating the reflectivity R of the simulated single-layer absorbing material with thicknesses of 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, and 3.0 mm are as follows: Figure 2 As shown:

[0068] As shown in the figure, for all thicknesses, the minimum reflectivity peak is less than -10dB (absorption rate greater than 90%), and the bandwidth with R < -10dB is relatively wide, exhibiting a certain broadband effect. When the material thickness is 2.2mm, its bandwidth with R < -10dB is approximately 2GHz, and at 5.6GHz, its minimum reflectivity peak is approximately -15.45dB (absorption rate approximately 97.15%). When the material thickness is 2.4mm, its bandwidth with R < -10dB is approximately 1.76GHz, and at 5.12GHz, its minimum reflectivity peak is approximately -16.76dB (absorption rate approximately 97.89%). When the material thickness is 2.6mm, its bandwidth with R < -10dB is approximately 1.6GHz, and at 4.72... At GHz, its minimum reflectivity peak value is approximately -18.27 dB (absorption rate approximately 98.51%); when the material thickness is 2.8 mm, its bandwidth with R < -10 dB is approximately 1.36 GHz, and at 4.4 GHz, its minimum reflectivity peak value is approximately -19.89 dB (absorption rate approximately 98.97%); when the material thickness is 3.0 mm, its bandwidth with R < -10 dB is approximately 1.2 GHz, and at 4.08 GHz, its minimum reflectivity peak value is approximately -20.98 dB (absorption rate approximately 99.20%). Therefore, Fe 65 Si 29.6 Al 5.4 It has certain wave-absorbing properties.

[0069] B. For the Fe prepared in Example 1 63 Si 29.6 Al 5.4 The results of calculating the reflectivity R of Gd2 for simulated single-layer absorbing material with thicknesses of 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, and 3.0 mm are as follows: Figure 3 As shown:

[0070] As shown in the figure, for all thicknesses, the minimum reflectivity peak is less than -10dB (absorption rate greater than 90%), and the bandwidth with R < -10dB is relatively wide, exhibiting a certain broadband effect. When the material thickness is 2.2mm, its bandwidth with R < -10dB is approximately 2.08GHz, and at 5.84GHz, its minimum reflectivity peak is approximately -16.30dB (absorption rate approximately 97.66%). When the material thickness is 2.4mm, its bandwidth with R < -10dB is approximately 1.84GHz, and at 5.2GHz, its minimum reflectivity peak is approximately -18.73dB (absorption rate approximately 98.66%). When the material thickness is 2.6mm, its bandwidth with R < -10dB is approximately 1.6GHz, and at 4.8... At GHz, its minimum reflectivity peak value is approximately -21.71dB (absorption rate is approximately 99.33%); when the material thickness is 2.8mm, its bandwidth with R < -10dB is approximately 1.44GHz, and at 4.4GHz, its minimum reflectivity peak value is approximately -20.56dB (absorption rate is approximately 99.12%); when the material thickness is 3.0mm, its bandwidth with R < -10dB is approximately 1.28GHz, and at 4.08GHz, its minimum reflectivity peak value is approximately -22.53dB (absorption rate is approximately 99.44%).

[0071] C. For the Fe prepared in Example 2 61 Si 29.6 Al 5.4 The reflectivity R calculated and simulated for Gd4 with single-layer absorbing material thicknesses of 2.2mm, 2.4mm, 2.6mm, 2.8mm, and 3.0mm is as follows: Figure 4 As shown:

[0072] As shown in the figure, for all thicknesses, the minimum reflectivity peak is less than -10dB (absorption rate greater than 90%), and the bandwidth with R < -10dB is relatively wide, exhibiting a certain broadband effect. When the material thickness is 2.2mm, its bandwidth with R < -10dB is approximately 1.92GHz, and at 5.52GHz, its minimum reflectivity peak is approximately -16.91dB (absorption rate approximately 97.96%). When the material thickness is 2.4mm, its bandwidth with R < -10dB is approximately 1.68GHz, and at 4.96GHz, its minimum reflectivity peak is approximately -19.94dB (absorption rate approximately 98.99%). When the material thickness is 2.6mm, its bandwidth with R < -10dB is approximately 1.44GHz, and at 4.5... At 6 GHz, its minimum reflectivity peak value is approximately -22.95 dB (absorption rate is approximately 99.49%); when the material thickness is 2.8 mm, its bandwidth with R < -10 dB is approximately 1.36 GHz, and at 4.16 GHz, its minimum reflectivity peak value is approximately -26.92 dB (absorption rate is approximately 99.80%); when the material thickness is 3.0 mm, its bandwidth with R < -10 dB is approximately 1.28 GHz, and at 3.92 GHz, its minimum reflectivity peak value is approximately -33.26 dB (absorption rate is approximately 99.95%).

[0073] D. Regarding the Fe prepared in Example 3 59 Si 29.6 Al 5.4 The reflectivity R calculated and simulated for Gd6 with single-layer absorbing material thicknesses of 2.2mm, 2.4mm, 2.6mm, 2.8mm, and 3.0mm is as follows: Figure 5 As shown:

[0074] As shown in the figure, for all thicknesses, the minimum reflectivity peak is less than -10dB (absorption rate greater than 90%), and the bandwidth with R < -10dB is relatively wide, exhibiting a certain broadband effect. When the material thickness is 2.2mm, its bandwidth with R < -10dB is approximately 2.4GHz, and at 6.4GHz, its minimum reflectivity peak is approximately -15.90dB (absorption rate approximately 97.43%). When the material thickness is 2.4mm, its bandwidth with R < -10dB is approximately 2.16GHz, and at 5.68GHz, its minimum reflectivity peak is approximately -18.32dB (absorption rate approximately 98.53%). When the material thickness is 2.6mm, its bandwidth with R < -10dB is approximately 1.92GHz, and at 5.2... At GHz, its minimum reflectivity peak value is approximately -22.61dB (absorption rate is approximately 99.45%); when the material thickness is 2.8mm, its bandwidth with R < -10dB is approximately 1.72GHz, and at 4.8GHz, its minimum reflectivity peak value is approximately -28.72dB (absorption rate is approximately 99.87%); when the material thickness is 3.0mm, its bandwidth with R < -10dB is approximately 1.36GHz, and at 4.48GHz, its minimum reflectivity peak value is approximately -36.62dB (absorption rate is approximately 99.98%).

[0075] E. Regarding the Fe prepared in Example 4 57 Si 29.6 Al 5.4 The reflectivity R calculated and simulated for Gd8 with single-layer absorbing material thicknesses of 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, and 3.0 mm is as follows: Figure 6 As shown:

[0076] As shown in the figure, for all thicknesses, the minimum reflectivity peak is less than -10dB (absorption rate greater than 90%), and the bandwidth with R < -10dB is relatively wide, exhibiting a certain broadband effect. When the material thickness is 2.2mm, its bandwidth with R < -10dB is approximately 2.32GHz, and at 6.48GHz, its minimum reflectivity peak is approximately -14.97dB (absorption rate approximately 96.82%). When the material thickness is 2.4mm, its bandwidth with R < -10dB is approximately 2GHz, and at 5.84GHz, its minimum reflectivity peak is approximately -15.83dB (absorption rate approximately 97.39%). When the material thickness is 2.6mm, its bandwidth with R < -10dB is approximately 1.84GHz, and at 5.2... At GHz, its minimum reflectivity peak value is approximately -17.55dB (absorption rate is approximately 98.24%); when the material thickness is 2.8mm, its bandwidth with R < -10dB is approximately 1.68GHz, and at 4.8GHz, its minimum reflectivity peak value is approximately -18.87dB (absorption rate is approximately 98.70%); when the material thickness is 3.0mm, its bandwidth with R < -10dB is approximately 1.44GHz, and at 4.4GHz, its minimum reflectivity peak value is approximately -20.28dB (absorption rate is approximately 99.06%).

[0077] E. Test the reflectivity loss of the absorbing materials prepared in Examples 1-4 and Comparative Example 1 at a thickness of 3.0 mm:

[0078] The results are as follows Figure 1 The minimum reflectance peak value of the FeSiAlGd material increases with increasing Gd content, reaching a maximum at 0.06. Furthermore, the minimum reflectance peak values ​​are all less than -10 dB (absorption rate greater than 90%) when the Gd content is 0, 0.02, 0.04, 0.06, and 0.08. When the Gd content is 0, 0.02, 0.04, 0.06, and 0.08, the frequencies of the reflectance loss resonance peaks of the powder are 4.08 GHz, 4.08 GHz, 3.92 GHz, 4.48 GHz, and 4.4 GHz, respectively. The corresponding reflectance peak values ​​are -20.98 dB, -22.53 dB, -33.26 dB, -36.62 dB, and -20.28 dB, respectively, with effective bandwidths of R < -10 dB of 1.2 GHz, 1.28 GHz, 1.28 GHz, 1.36 GHz, and 1.44 GHz, respectively. The above data indicates that the powder has a certain absorption bandwidth and absorption performance in the 2-18GHz frequency band.

[0079] As can be seen from Examples 1-4 and Comparative Example 1, the present invention utilizes Fe... 65 Si 29.6 Al 5.4The addition of Gd significantly improves the minimum reflectance peak and effective bandwidth of the material, especially for Fe composition. 59 Si 29.6 Al 5.4 The minimum reflectivity peak value of the Gd6 alloy increased from -20.98dB to -36.62dB, and the bandwidth widened from 1.2GHz to 1.36GHz. The minimum reflectivity peak value, corresponding frequency, and effective bandwidth after adding Gd are shown in Table 1.

[0080] Table 1. Fe 65-x Si 29.6 Al 5.4 Gd x Wave absorption performance of (x=0,2,4,6,8) at d=3.0mm

[0081]

[0082] As can be seen from the above embodiments, the present invention provides a FeSiAlGd microwave absorbing material that can absorb electromagnetic waves in the 2-18 GHz microwave band, has a wide absorption bandwidth, high absorption efficiency (>90%), and exhibits certain thermal stability due to its high alloy heat treatment temperature. Furthermore, the material's low density meets the requirement of lightweight microwave absorbing materials. The present invention also provides a method for preparing the FeSiAlGd microwave absorbing material, which can be obtained through melting, heat treatment, and ball milling. The preparation process is simple and suitable for large-scale production.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A FeSiAlGd microwave absorbing material, characterized in that, The molecular formula of the FeSiAlGd microwave absorbing material is Fe x Si 29.6 Al 5.4 Gd y , where 57 < x ≤ 65, 0 < y ≤ 8, and the FeSiAlGd microwave absorbing material is prepared by a preparation method including the following steps: (1) Weigh the metal iron, silicon, aluminum and gadolinium in proportion and perform electric arc melting in a non-consumable vacuum electric arc furnace to obtain metal ingots for later use; (2) The above metal ingots are heat-treated at a temperature of 800°C for 4 days, and then coarsely crushed and ground in a crushing tank to obtain metal powder. (3) The above metal powder was ball-milled to obtain FeSiAlGd microwave absorbing material.

2. A method for preparing the FeSiAlGd microwave absorbing material as described in claim 1, characterized in that, Includes the following steps: (1) Weigh the metal iron, silicon, aluminum and gadolinium in proportion and perform electric arc melting in a non-consumable vacuum electric arc furnace to obtain metal ingots for later use; (2) The above metal ingots are heat-treated at a temperature of 800°C for 4 days, and then coarsely crushed and ground in a crushing tank to obtain metal powder. (3) The above metal powder was ball-milled to obtain FeSiAlGd microwave absorbing material.

3. The method for preparing a FeSiAlGd microwave absorbing material according to claim 2, characterized in that: The purity of the metals iron, silicon, aluminum, and gadolinium is equal to or greater than 99.9%.

4. The method for preparing a FeSiAlGd microwave absorbing material according to claim 2, characterized in that: The melting loss rate of the smelted metal ingot is less than 1 wt.%.

5. The method for preparing a FeSiAlGd microwave absorbing material according to claim 2, characterized in that: The vacuum degree during arc melting in step (1) is less than 3 × 10. -3 Pa.

6. The method for preparing a FeSiAlGd microwave absorbing material according to claim 2, characterized in that: In step (2), the metal ingot is first sealed before heat treatment.

7. The method for preparing a FeSiAlGd microwave absorbing material according to claim 2, characterized in that: The coarsely crushed and ground metal powder from step (2) is poured into an agate mortar for grinding and then passed through a 100-mesh sieve.

8. The method for preparing a FeSiAlGd microwave absorbing material according to claim 2, characterized in that: In step (3), the ball milling speed is 260-360 r / min and the ball milling time is 20h.

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