A NiSiAlGd microwave absorbing material and its preparation method

Abstract

This invention provides a NiSiAlGd microwave absorbing material and its preparation method, relating to the field of microwave absorbing materials technology. The molecular formula of the NiSiAlGd microwave absorbing material is Ni... x Si 49.6 Al 5.4 Gd y The composition of the absorbing material is 37 < x ≤ 45 and 0 ≤ y ≤ 8. This absorbing material can absorb electromagnetic waves in the 2~18 GHz microwave band, with a wide effective absorption bandwidth and high absorption efficiency (>90%). The absorbing material has excellent thermal stability. At the same time, this invention provides a method for preparing the NiSiAlGd absorbing material mentioned above. The absorbing material can be obtained by arc melting, heat treatment and ball milling. 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 NiSiAlGd microwave absorbing material and its preparation method. Background Technology

[0002] With the development of modern science and technology, various electronic and electrical equipment have brought high efficiency to social production and great convenience to people's daily lives.

[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, 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, meeting 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, utilizing the properties of rare earth elements to adjust and optimize the electromagnetic parameters of microwave absorbing materials can significantly improve absorption performance. Developing high-performance, low-frequency rare earth magnetic microwave absorbing materials will broaden and increase the application areas and value of rare earth elements. Summary of the Invention

[0005] This invention provides a NiSiAlGd 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 NiSiAlGd microwave absorbing material with the molecular formula Ni x Si 49.6 Al 5.4 Gd y , where 37<x≤45, 0≤y≤8.

[0008] The preferred molecular formula of the NiSiAlGd absorbing material is Ni （37~43） Si 49.6 Al 5.4 Gd （2~8） Ni is preferred. (37~41) Si 49.6 Al 5.4 Gd （4~8） The optimal choice is Ni. 37 Si 49.6 Al 5.4 Gd8.

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

[0010] (1) Weigh nickel, silicon, aluminum and gadolinium in proportion and perform arc melting in a non-consumable vacuum 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 NiSiAlGd microwave absorbing material.

[0013] Preferably, the nickel, silicon, aluminum and gadolinium are elemental metals, and the purity of the nickel, 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 smelted 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 1~5×10. -1 Pa, more preferably 1 to 2 x 10 Pa -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 zirconia 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 NiSiAlGd 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 to 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 resonance 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 >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 NiSiAlGd 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 Figure Description

[0029] Figure 1 The reflectivity loss diagrams of the NiSiAlGd absorbing materials prepared in Examples 1-4 and Comparative Example 1 of this invention are shown when the thickness is 2.0 mm.

[0030] Figure 2 Ni prepared as Comparative Example 1 of this invention 45 Si 49.6 Al 5.4 Reflectance loss of absorbing material at different simulated thicknesses;

[0031] Figure 3 Ni prepared in Example 1 of this invention 43 Si 49.6 Al 5.4 Reflectance loss diagram of Gd2 absorbing material at different simulated thicknesses;

[0032] Figure 4 Ni prepared in Example 2 of this invention 41 Si 49.6 Al 5.4 Reflectance loss diagram of Gd4 absorbing material at different simulated thicknesses;

[0033] Figure 5 Ni prepared in Example 3 of this invention 39 Si 49.6 Al 5.4 Reflectivity loss diagram of Gd6 absorbing material at different simulated thicknesses.

[0034] Figure 6 Ni prepared in Example 4 of this invention 37 Si 49.6 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 Ni 43 Si 49.6 Al 5.4 Gd2 magnetic absorbing material:

[0038] (1) According to the molecular formula Ni 43 Si 49.6 Al 5.4 1.4903g ​​of nickel (99.99% purity), 0.8226g of silicon, 0.5014g of aluminum, and 0.1857g of gadolinium (99.99% purity) were weighed out and placed in a non-consumable vacuum melting furnace for melting. The furnace vacuum reached 3.0 x 10⁻⁶. -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated more than 2 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 10 h 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 Ni. 43 Si 49.6 Al 5.4 Gd2.

[0041] Example 2:

[0042] Preparation of Ni 41 Si 49.6 Al 5.4 Gd4 magnetic absorbing material

[0043] (1) According to the molecular formula Ni 41 Si 49.6 Al 5.4 Weigh out 1.3679g of nickel (99.99% purity), 0.7918g of silicon, 0.4827g of aluminum, and 0.3576g of gadolinium. Place the metals in a non-consumable vacuum melting furnace for melting. When the furnace vacuum reaches 3.0 x 10... -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated more than 2 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 10 h 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 Ni. 41 Si 49.6 Al 5.4 Gd4.

[0046] Example 3:

[0047] Preparation of Ni 39 Si 49.6 Al 5.4 Gd6 magnetic absorbing material

[0048] (1) According to the molecular formula Ni 39 Si 49.6 Al 5.4 Weigh out 1.2543g of nickel (99.99% purity), 0.7633g of silicon, 0.4653g of aluminum, and 0.5170g of gadolinium. Place the metals in a non-consumable vacuum melting furnace for melting. When the furnace vacuum reaches 3.0 x 10... -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated more than 2 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 10 h 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 Ni. 39 Si 49.6 Al 5.4 Gd6.

[0051] Example 4:

[0052] Preparation of Ni 37 Si 49.6 Al 5.4 Gd8 magnetic absorbing material

[0053] (1) According to the molecular formula Ni 37Si 49.6 Al 5.4 Gd8 was weighed with 1.1487g of nickel (99.99% purity), 0.7368g of silicon, 0.4491g of aluminum, and 0.6654g of gadolinium. The metals were placed in a non-consumable vacuum melting furnace for melting. When the furnace vacuum reached 3.0 x 10... -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated more than 2 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 10 h 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 Ni. 37 Si 49.6 Al 5.4 Gd8.

[0056] Comparative Example 1:

[0057] Preparation of Ni 45 Si 49.6 Al 5.4 Magnetic absorbing materials

[0058] (1) According to the molecular formula Ni 45 Si 49.6 Al 5.4 Weigh out 1.6226g of nickel (99.99% purity), 0.8558g of silicon, and 0.5217g of aluminum. Place the metals in a non-consumable vacuum melting furnace for melting. When the furnace vacuum reaches 3.0 x 10... -3 After Pa, argon gas is introduced for protection, and the melting current is 80-90A. The melting is repeated more than 2 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 10 h 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 Ni. 45 Si 49.6 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 were measured in the 2–18 GHz frequency band 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, , 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 Ni prepared in Comparative Example 1 45 Si 49.6 Al 5.4 The results of calculating the reflectivity R of the simulated single-layer absorbing material with thicknesses of 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, and 2.8 mm are as follows: Figure 2 As shown:

[0068] As can be seen from the figure, the minimum reflectivity peak is less than -10dB (absorption rate is greater than 90%) for all thicknesses, and the bandwidth of R<-10dB is relatively wide, which has a certain broadband effect. When the material thickness is 1.8 mm, its bandwidth with R<-10 dB is approximately 2.08 GHz, and its minimum reflectivity peak at 10.56 GHz is approximately -13.40 dB (absorption rate approximately 95.43%). When the material thickness is 2.0 mm, its bandwidth with R<-10 dB is approximately 1.36 GHz, and its minimum reflectivity peak at 8.96 GHz is approximately -14.30 dB (absorption rate approximately 96.28%). When the material thickness is 2.2 mm, its bandwidth with R<-10 dB is approximately 1.6 GHz, and its minimum reflectivity peak at 8 GHz is approximately -17.23 dB (absorption rate approximately 98.11%). When the material thickness is 2.4 mm, its bandwidth with R<-10 dB is approximately 1.04 GHz, and its minimum reflectivity peak at 7.28 GHz is approximately -18.83 dB. The absorptivity is approximately 98.69% (dB); when the material thickness is 2.6 mm, its bandwidth with R < -10 dB is approximately 1.44 GHz, and its minimum reflectivity peak at 6.56 GHz is approximately -18.68 dB (absorptivity approximately 98.64%). When the material thickness is 2.8 mm, its bandwidth with R < -10 dB is approximately 1.2 GHz, and its minimum reflectivity peak at 6.0 GHz is approximately -17.08 dB (absorptivity approximately 98.04%). Therefore, Ni 45 Si 49.6 Al 5.4 It has certain wave-absorbing properties.

[0069] B. Regarding the Ni prepared in Example 1 43 Si 49.6 Al 5.4 The results of calculating the reflectivity R of Gd2 for simulated single-layer absorbing material thicknesses of 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, and 2.8 mm are as follows: Figure 3 As shown:

[0070] As can be seen from the figure, the minimum reflectivity peak is less than -10dB (absorption rate is greater than 90%) for all thicknesses, and the bandwidth of R<-10dB is relatively wide, which has a certain broadband effect. When the material thickness is 1.8 mm, its bandwidth with R<-10 dB is approximately 3.28 GHz, and its minimum reflectivity peak at 10.24 GHz is approximately -20.83 dB (absorption rate approximately 99.18%). When the material thickness is 2.0 mm, its bandwidth with R<-10 dB is approximately 2.4 GHz, and its minimum reflectivity peak at 8.96 GHz is approximately -23.38 dB (absorption rate approximately 99.54%). When the material thickness is 2.2 mm, its bandwidth with R<-10 dB is approximately 2 GHz, and its minimum reflectivity peak at 7.92 GHz is approximately -25 dB (absorption rate approximately 99.68%). When the material thickness is 2.4 mm, its bandwidth with R<-10 dB is approximately 1.84 GHz, and its minimum reflectivity peak at 7.12 GHz is approximately -26.37 dB. The absorbance is approximately 99.77% (dB). When the material thickness is 2.6 mm, the bandwidth with R < -10 dB is approximately 1.6 GHz, and the minimum peak reflectance at 6.4 GHz is approximately -22.88 dB (absorbance approximately 99.48%). When the material thickness is 2.8 mm, the bandwidth with R < -10 dB is approximately 1.36 GHz, and the minimum peak reflectance at 5.92 GHz is approximately -19.67 dB (absorbance approximately 98.92%).

[0071] C. Regarding the Ni prepared in Example 2 41 Si 49.6 Al 5.4 The reflectivity R calculated and simulated for Gd4 with single-layer absorbing material thicknesses of 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, and 2.8 mm is shown below. Figure 4 As shown:

[0072] As can be seen from the figure, the minimum reflectivity peak is less than -10dB (absorption rate is greater than 90%) for all thicknesses, and the bandwidth of R<-10dB is relatively wide, which has a certain broadband effect. When the material thickness is 1.8 mm, its bandwidth with R<-10 dB is approximately 3.04 GHz, and its minimum reflectivity peak at 10.16 GHz is approximately -19.64 dB (absorption rate approximately 98.91%). When the material thickness is 2.0 mm, its bandwidth with R<-10 dB is approximately 2.56 GHz, and its minimum reflectivity peak at 9.04 GHz is approximately -27.69 dB (absorption rate approximately 99.83%). When the material thickness is 2.2 mm, its bandwidth with R<-10 dB is approximately 2 GHz, and its minimum reflectivity peak at 8 GHz is approximately -21.14 dB (absorption rate approximately 99.03%). When the material thickness is 2.4 mm, its bandwidth with R<-10 dB is approximately 1.6 GHz, and its minimum reflectivity peak at 7.28 GHz is approximately -23.38 dB. The absorbance is approximately 99.54% (dB); when the material thickness is 2.6 mm, its bandwidth with R < -dB is approximately 1.6 GHz, and its minimum peak reflectance at 6.64 GHz is approximately -25.14 dB (absorbance approximately 99.69%); when the material thickness is 2.8 mm, its bandwidth with R < -10 dB is approximately 1.6 GHz, and its minimum peak reflectance at 6.08 GHz is approximately -30.46 dB (absorbance approximately 99.91%).

[0073] D. Regarding the Ni prepared in Example 3 39 Si 49.6 Al 5.4 The reflectivity R calculated and simulated for Gd6 with single-layer absorbing material thicknesses of 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, and 2.8 mm is shown below. Figure 5 As shown:

[0074] As can be seen from the figure, the minimum reflectivity peak is less than -10dB (absorption rate is greater than 90%) for all thicknesses, and the bandwidth of R<-10dB is relatively wide, which has a certain broadband effect. When the material thickness is 1.8 mm, its bandwidth with R<-10 dB is approximately 2.8 GHz, and its minimum reflectivity peak at 10.96 GHz is approximately -19.42 dB (absorption rate approximately 99.88%). When the material thickness is 2.0 mm, its bandwidth with R<-10 dB is approximately 3.36 GHz, and its minimum reflectivity peak at 9.68 GHz is approximately -44.31 dB (absorption rate approximately 99.99%). When the material thickness is 2.2 mm, its bandwidth with R<-10 dB is approximately 2.24 GHz, and its minimum reflectivity peak at 8.72 GHz is approximately -14.75 dB (absorption rate approximately 96.65%). When the material thickness is 2.4 mm, its bandwidth with R<-10 dB is approximately 1.36 GHz, and its minimum reflectivity peak at 7.68 GHz is approximately -19.42 dB (absorption rate approximately 99.88%). At GHz, its minimum reflectivity peak value is approximately -13.80 dB (absorption rate is approximately 95.83%); when the material thickness is 2.6 mm, its bandwidth with R < -10 dB is approximately 1.12 GHz, and at 7.04 GHz, its minimum reflectivity peak value is approximately -13.96 dB (absorption rate is approximately 95.98%); when the material thickness is 2.8 mm, its bandwidth with R < -10 dB is approximately 0.88 GHz, and at 6.4 GHz, its minimum reflectivity peak value is approximately -12.99 dB (absorption rate is approximately 94.98%).

[0075] E. Regarding the Ni prepared in Example 4 37 Si 49.6 Al 5.4 The reflectivity R calculated and simulated for Gd8 with single-layer absorbing material thicknesses of 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, and 2.8 mm is shown below. Figure 6 As shown:

[0076] As can be seen from the figure, the minimum reflectivity peak is less than -10 dB (absorption rate is greater than 90%) for all thicknesses, and the bandwidth of R<-10dB is relatively wide, which has a certain broadband effect. When the material thickness is 1.8 mm, its bandwidth with R<-10 dB is approximately 1.68 GHz, and its minimum reflectivity peak at 9.44 GHz is approximately -21.34 dB (absorption rate approximately 99.27%). When the material thickness is 2.0 mm, its bandwidth with R<-10 dB is approximately 1.92 GHz, and its minimum reflectivity peak at 8.4 GHz is approximately -22.36 dB (absorption rate approximately 99.42%). When the material thickness is 2.2 mm, its bandwidth with R<-10 dB is approximately 1.68 GHz, and its minimum reflectivity peak at 7.44 GHz is approximately -26.37 dB (absorption rate approximately 99.77%). When the material thickness is 2.4 mm, its bandwidth with R<-10 dB is approximately 1.52 GHz, and its minimum reflectivity peak at 6.64 GHz is approximately -28.54 dB. The absorbance is approximately 99.86% (dB); when the material thickness is 2.6 mm, its bandwidth with R < -dB is approximately 1.36 GHz, and its minimum peak reflectance at 6.08 GHz is approximately -26.02 dB (absorbance approximately 99.75%); when the material thickness is 2.8 mm, its bandwidth with R < -10 dB is approximately 1.12 GHz, and its minimum peak reflectance at 5.52 GHz is approximately -22.99 dB (absorbance approximately 99.50%).

[0077] E. Test the reflectivity loss of the absorbing materials prepared in Examples 1-4 and Comparative Example 1 at a thickness of 2.0 mm:

[0078] The results are as follows Figure 1As shown, the peak reflectance first increases and then decreases with increasing Gd content (reaching its maximum value when the Gd content is 0.06), and the minimum peak reflectance is 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 at which the powder exhibits reflectance loss resonance peaks are 8.96 GHz, 8.96 GHz, 9.04 GHz, 9.68 GHz, and 8.4 GHz, respectively, with corresponding peak reflectance values ​​of -14.30 dB, -23.38 dB, -27.69 dB, -44.31 dB, and -22.36 dB, respectively. The effective bandwidths with R < -10 dB are 1.36 GHz, 2.40 GHz, 2.56 GHz, 3.36 GHz, and 1.92 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 Ni 45 Si 49.6 Al 5.4 The addition of Gd significantly improves the minimum reflectivity peak and effective bandwidth of the material, especially when the composition is Ni. 37 Si 49.6 Al 5.4 The Gd6 alloy has a minimum reflectivity peak value increased to -44.31 dB and a bandwidth widened to 3.36 GHz. The minimum reflectivity peak value, corresponding frequency, and effective bandwidth after adding Gd are shown in Table 1.

[0080] Table 1. Ni 45-x Si 49.6 Al 5.4 Gd x Wave absorption performance of (x=0, 2, 4, 6, 8) at d=2mm

[0081] Sample <![CDATA[RL min (dB)]]> <![CDATA[f m (GHz)]]> EAB (GHz) <![CDATA[Ni 45 Yeah 49.6 To the 5.4 ]]> -14.30 8.96 1.36 <![CDATA[Ni 43 And 49.6 the 5.4 Gd2]]> -23.38 8.96 2.40 <![CDATA[Ni 41 Yeah 49.6 To the 5.4 Gd4]]> -27.69 9.04 2.56 <![CDATA[Ni 39 And 49.6 the 5.4 Gd6]]> -44.31 9.68 3.36 <![CDATA[Ni 37 Yes 49.6 To the 5.4 Gd8]]> -22.36 8.4 1.92

[0082] As can be seen from the above embodiments, the present invention provides a NiSiAlGd microwave absorbing material that can absorb electromagnetic waves in the 2~18GHz microwave band, with a wide absorption bandwidth and high absorption efficiency (>90%). Furthermore, the alloy has a high heat treatment temperature and exhibits certain thermal stability. In addition, due to its low density, this material meets the requirement of lightweight microwave absorbing materials. The present invention also provides a method for preparing the NiSiAlGd 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 NiSiAlGd wave-absorbing material, characterized in that, The molecular formula of the NiSiAlGd absorbing material is NixSi49.6Al5.4Gdy, where 37≤x≤43 and 2≤y≤8.

2. The preparation method of the NiSiAlGd wave-absorbing material according to claim 1, characterized in that, Includes the following steps: (1) Weigh nickel, silicon, aluminum and gadolinium in proportion and perform arc melting in a non-consumable vacuum arc furnace to obtain metal ingots for later use; (2) The above metal ingots are heat-treated and then coarsely crushed to obtain metal powder; (3) The above metal powder was ball-milled to obtain NiSiAlGd microwave absorbing material.

3. The preparation method of the NiSiAlGd wave-absorbing material according to claim 2, characterized in that: The purity of the metals nickel, silicon, aluminum, and gadolinium is equal to or greater than 99.9%.

4. The preparation method of the NiSiAlGd wave-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 preparation method of the NiSiAlGd wave-absorbing material according to claim 2, characterized in that: The heat treatment temperature in step (2) is 800℃ and the heat treatment time is 4 days.

6. The preparation method of the NiSiAlGd wave-absorbing material according to claim 2, characterized in that: In step (2), the oxide layer of the heat-treated metal ingot is removed before coarse crushing.

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

8. A method for preparing a NiSiAlGd 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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