High-entropy max phase material, preparation method and application thereof

Abstract

This invention discloses a high-entropy MAX phase material, its preparation method, and its applications, comprising: placing vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder in a mortar, adding anhydrous ethanol for grinding and mixing, vacuum drying, then transferring to an alumina container, sintering under an inert atmosphere, and naturally cooling to room temperature under an inert atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC; will (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 AlC, ferrous chloride, and potassium chloride are ground and mixed. The mixed powder is transferred to an alumina container and sintered under an inert atmosphere. Then, it is naturally cooled to room temperature under an inert atmosphere, ground again, soaked in deionized water, washed, and dried to obtain the high-entropy MAX phase material (V). 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC. The high-entropy MAX phase material (V) with magnetic properties prepared by this invention 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2FeC has excellent electromagnetic wave absorption and corrosion resistance. At room temperature, it exhibits "thin, light, wide, and strong" electromagnetic wave absorption characteristics, and has good application prospects.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy MAX phase material preparation technology. More specifically, this invention relates to high-entropy MAX phase materials, their preparation methods, and applications. Background Technology

[0002] With the application and development of electromagnetic wave technology, the electromagnetic environment of human living space is deteriorating. Electromagnetic wave absorbing and shielding materials are of great significance for avoiding electromagnetic interference, protecting personnel safety, improving equipment reliability, and ensuring the safe and smooth operation of network systems. Traditional electromagnetic wave absorbing materials such as ferrite have disadvantages such as easy corrosion and heavy weight. In order to meet the comprehensive requirements of "thin, light, wide, strong" and corrosion resistance of new electromagnetic wave absorbing materials, ternary layered transition metal carbon / nitrogen compound MAX phase materials have attracted attention in the electromagnetic field due to their unique layered structure and the excellent properties of ceramics and metals. However, when applied in the field of wave absorption, they still face the following problems: (1) The high conductivity of MAX phase affects impedance matching, causing a large amount of electromagnetic waves to be reflected on the material surface; (2) MAX phase materials mainly dissipate electromagnetic energy through conductivity loss mechanism. The loss mechanism is simple and difficult to support strong electromagnetic wave absorption performance.

[0003] Typically, the design and fabrication of electromagnetic wave absorbing materials focus on two main aspects: material composition design and microstructure control. For MAX phases, increasing the entropy of elements at the M, A, and X sites can effectively control their physicochemical properties. However, the synthesis of high-entropy MAX phases remains challenging, with only a few M-site high-entropy MAX phases reported so far involving electromagnetic wave absorption performance studies. Furthermore, M-site high-entropy MAX phases are dielectric loss-type absorbing materials, making effective absorption at low frequencies difficult; currently, the absorption frequency band is mainly concentrated above 8.0 GHz. The rich elemental composition of high-entropy materials facilitates the control of electromagnetic parameters and enhances the electromagnetic wave loss mechanism. Magnetic loss, dominated by magnetic materials, can effectively shift the absorption frequency band to lower frequencies. Therefore, the successful development of magnetic high-entropy MAX phases and their application in the field of electromagnetic wave absorption is of great significance. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] To achieve these objectives and other advantages of the present invention, a high-entropy MAX phase material is provided, the chemical formula of which is (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC.

[0006] The preparation method of the high-entropy MAX phase material as described above includes the following steps:

[0007] Step 1: Vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder are placed in an agate mortar, and anhydrous ethanol is added for grinding and mixing. After vacuum drying, the mixed powder is transferred to an alumina container, which is then placed in a tube furnace and sintered under an inert atmosphere. The mixture is then naturally cooled to room temperature under an inert atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC;

[0008] Step 2, (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2AlC, ferrous chloride, and potassium chloride were ground and mixed. The mixed powder was transferred to an alumina container and placed in a tube furnace for sintering under an inert atmosphere. The mixture was then naturally cooled to room temperature under an inert atmosphere, ground again, soaked in deionized water, washed, and dried to obtain the high-entropy MAX phase material (V). 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC.

[0009] Preferably, in step one, the molar ratio of V, Nb, Zr, Ta, Al, and C in vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder is 0.4–0.6:0.4–0.6:0.4–0.6:0.4–0.6:1–1.2:1.

[0010] Preferably, in step one, the grinding time is 20-40 min; the vacuum drying temperature is 70-90℃; and the drying time is 10-14 h.

[0011] Preferably, in step one, the sintering process is as follows: the temperature is increased to 1500-1700℃ at a heating rate of 4-6℃ / min, and held for 120-240min.

[0012] Preferably, in step two, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The molar ratio of AlC, ferrous chloride and potassium chloride is 1:1.3-1.7:5-7.

[0013] Preferably, in step two, the grinding time is 20-40 min; the sintering method is as follows: the temperature is raised to 600-700℃ at a heating rate of 4-6℃ / min, and held for 360-480 min.

[0014] Preferably, in step two, the water is soaked in deionized water for 1 to 3 hours; washed 2 to 4 times; and dried at 50 to 70°C for 20 to 28 hours.

[0015] Preferably, in steps one and two, the inert atmosphere is an argon atmosphere.

[0016] Preferably, it also includes the step of obtaining (V) in step one. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC is preprocessed. The specific method of preprocessing is as follows: (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2AlC and 30-60wt% ethanol solution were mixed and stirred evenly, then irradiated in an ultrasonic and electron beam environment for 20-40 min. The ultrasonic frequency was 40-80 kHz and the ultrasonic power was 300-600 W. The electron beam irradiation dose rate was 180-250 Gy / min. After irradiation, the mixture was vacuum dried at 80℃ for 20-40 h to obtain the pretreated (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC.

[0017] Preferably, the (Ti) 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 The molar volume ratio of 2AlC and ethanol solution is 1 mol: 600-1000 mL; the ultrasonic and electron beam environment is a sealed environment, which is first purged with argon gas to purge other gases before sealing.

[0018] Application of a high-entropy MAX phase material prepared by the method described above in electromagnetic wave absorption.

[0019] The present invention includes at least the following beneficial effects: The present invention uses (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC is reacted with ferrous chloride (FeCl2) using a substitution method in a molten salt potassium chloride (KCl) environment, where Fe replaces Al in the high-entropy MAX phase, thus preparing a magnetic high-entropy MAX phase material (V 0.25 Nb 0.25 Zr 0.25 Ta 0.252FeC has excellent electromagnetic wave absorption and corrosion resistance. At room temperature, it exhibits "thin, light, wide, and strong" electromagnetic wave absorption characteristics, and has good application prospects.

[0020] Among them, (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 By selecting an appropriate absorption thickness within the research frequency range (1–18 GHz), 90% effective absorption (reflection loss < -10 dB) can be achieved across the entire frequency band with 2FeC. At 6.27 GHz and a thickness of 1.5 mm, RL... min It achieved -43.7dB (99.99% effective absorption), and the effective absorption bandwidth reached 13GHz (2.9~15.9GHz) with a thickness of 1.5mm, spanning the C-Ku band.

[0021] Furthermore, the present invention also addresses (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 Pretreatment of Al2C with ultrasound and electron beam irradiation makes it easier for Fe to enter and replace Al. The resulting product has a stable structure and high crystallinity, which is conducive to further improving its microwave absorption ability.

[0022] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0023] Figure 1 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC, Comparative Example 1 prepared (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 XRD patterns of 2AlC, V2AlC, Zr2AlC, Ta2AlC and Nb2AlC;

[0024] Figure 2 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 SEM-EDS image of 2FeC;

[0025] Figure 3 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25Ta 0.25 The electromagnetic parameter relationship curves of M2FeC-Ti prepared by 2FeC and Comparative Example 1 are shown, where a to c are the curves of the real part (ε'), imaginary part (ε”) of its dielectric constant and the loss tangent value with frequency, and d to f are the curves of the real part (μ'), imaginary part (μ”) of its permeability and the loss tangent value with frequency.

[0026] Figure 4 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 CO curves of M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 1;

[0027] Figure 5 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 2 are all different types of FeC-Ti. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The reflection loss (RL) curves (a, c, e) and 2D contour lines (b, d, f) of 2AlC;

[0028] Figure 6 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 2 are all different types of FeC-Ti. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 Impedance matching (a, c, e) and 2D contour lines (b, d, f) of 2AlC;

[0029] Figure 7 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 Polarization curves of M2FeC-Ti prepared in 5% HCl solution for 2FeC and Comparative Example 1;

[0030] Figure 8 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25Polarization curves of M2FeC-Ti prepared in 5% NaOH solution for 2FeC and Comparative Example 1. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0032] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0033] The raw materials used in the following examples are: vanadium powder (99.9%), niobium powder (99.95%, ≥325 mesh), zirconium powder (99.9%), tantalum powder (99.9%, 325 mesh), aluminum powder (≥99.5%, 200 mesh), graphite powder (AR, 99%), ferrous chloride (98%), potassium chloride (AR, 99.5%), and titanium powder (99.5%).

[0034] Example 1

[0035] A method for preparing a high-entropy MAX phase material includes the following steps:

[0036] Step 1: Using a molar ratio of V:Nb:Zr:Ta:Al:C = 0.5:0.5:0.5:0.5:1.1:1, vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder are placed in an agate mortar. An appropriate amount of anhydrous ethanol is added, and the mixture is ground and mixed for 30 minutes. After vacuum drying at 80℃ for 12 hours, the mixed powder is transferred to an alumina boat, which is then placed in a tube furnace and sintered under an argon atmosphere. The temperature is increased to 1600℃ at a rate of 5℃ / min, held for 180 minutes, and then naturally cooled to room temperature under an argon atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC;

[0037] Step 2, (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 AlC, ferrous chloride, and potassium chloride were ground and mixed in a molar ratio of 1:1.5:6 for 30 min. The mixed powder was transferred to an alumina boat, which was then placed in a tube furnace and sintered under an argon atmosphere: the temperature was increased to 650℃ at a rate of 5℃ / min, held for 420 min, and then naturally cooled to room temperature under an argon atmosphere. The mixture was ground until fine, soaked in deionized water for 2 h, washed three times, and dried at 60℃ for 24 h to obtain the high-entropy MAX phase material (V). 0.25 Nb0.25 Zr 0.25 Ta 0.25 )2FeC.

[0038] Comparative Example 1

[0039] A method for preparing a high-entropy MAX phase material includes the following steps:

[0040] Step 1: Using a molar ratio of Ti:V:Nb:Zr:Ta:Al:C = 0.4:0.4:0.4:0.4:0.4:1.1:1, place titanium powder, vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder in an agate mortar. Add an appropriate amount of anhydrous ethanol and grind and mix for 30 minutes. After vacuum drying at 80℃ for 12 hours, transfer the mixed powder to an alumina boat and place the alumina boat in a tube furnace for sintering under an argon atmosphere: heat to 1600℃ at a heating rate of 5℃ / min, hold for 180 minutes, and then cool naturally to room temperature under an argon atmosphere to obtain (Ti 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 )2AlC;

[0041] Step 2, (Ti) 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 AlC, ferrous chloride, and potassium chloride were ground and mixed in a molar ratio of 1:1.5:6 for 30 min. The mixed powder was transferred to an alumina boat, which was then placed in a tube furnace and sintered under an argon atmosphere: the temperature was increased to 650℃ at a rate of 5℃ / min, held for 420 min, and then naturally cooled to room temperature under an argon atmosphere. The mixture was ground until fine, soaked in deionized water for 2 h, washed three times, and dried at 60℃ for 24 h to obtain the high-entropy MAX phase material (Ti). 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 M2FeC (abbreviated as M2FeC-Ti).

[0042] Comparative Example 2

[0043] A method for preparing a high-entropy MAX phase material includes: placing vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder in an agate mortar with a molar ratio of V:Nb:Zr:Ta:Al:C = 0.5:0.5:0.5:0.5:1.1:1, adding an appropriate amount of anhydrous ethanol, and grinding and mixing for 30 min. After vacuum drying at 80℃ for 12 h, the mixed powder is transferred to an alumina boat, and the alumina boat is placed in a tube furnace for sintering under an argon atmosphere: heating to 1600℃ at a heating rate of 5℃ / min, holding at that temperature for 180 min, and then naturally cooling to room temperature under an argon atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC.

[0044] Experimental methods:

[0045] XRD analysis: The X-ray diffractometer used was a Riguku MiniFlex 600 diffractometer from Japan; a Cu Ka X-ray source with a wavelength of λ = 1.54 Å was used, the diffraction angle range was 10–80°, and the scanning speed was 0.02° / s.

[0046] SEM-EDS Analysis: The scanning electron microscope used was a Bruker Quantax 200XFlash 6|60 from Germany, equipped with an X-ray energy dispersive spectroscopy (EDS) detector and an EBSD backscattered electron diffraction (EBSD) system. Before testing, gold sputtering was selectively applied to the samples based on their conductivity. The samples were then adhered to the sample stage using conductive adhesive and placed in the sample chamber. A vacuum was evacuated, and the sharpness of a 1 / 4 frame selection area was adjusted. The brightness was automatically adjusted to accurately determine the sample position. Focusing and astigmatism adjustment were then used to observe the microstructure of the samples, and TIFF images were captured and saved. After testing, the voltage was reduced, the sample stage returned to its original position, the push rod was inflated to remove the sample, and the exchange chamber was evacuated to a vacuum.

[0047] Vector network analyzer testing and analysis: The electromagnetic parameters of the material were measured using a vector network analyzer according to the transmission line principle. These parameters were then imported into Spyder software for simulation calculations of samples of different thicknesses. Finally, the simulated data was imported into Origin software for plotting, visually representing the magnitude of reflection loss and impedance matching performance, thus characterizing the material's microwave absorption performance. Electromagnetic wave absorption performance tests were conducted on high-entropy MAX phase materials prepared at different temperatures. The coaxial transmission reflection method was used to test the electromagnetic parameters of the samples in the range of 2–18 GHz, and the dielectric constant and permeability of the samples under room temperature conditions were analyzed. For sample preparation, the sample powder and paraffin were uniformly mixed at a mass ratio of 7:3, heated to 95°C, poured into a mold, and pressed into a coaxial ring sample with an outer diameter of 7.0 mm and an inner diameter of 3.0 mm. This invention used a PNA-N5234A vector network analyzer from Agilent Technologies, USA, to test the microwave absorption performance of high-entropy MAX phase materials.

[0048] Electrochemical testing and analysis: This invention was performed on a CHI750e electrochemical workstation, using a three-electrode system to test the electrochemical corrosion resistance of the samples. The test sample was mixed with conductive carbon black and polyvinylidene fluoride (PVDF) in an 8:1:1 ratio. An appropriate amount of N-methylpyrrolidone (NMP) was added to prepare an active material, which was then coated onto nickel foam. After drying for 12 hours, this material served as the working electrode. A platinum electrode with a large surface area was used as the auxiliary electrode, and a saturated calomel electrode (SCE) was used as the reference electrode. The samples were tested in 5% HCl solution and 5% NaOH solution. During testing, the open-circuit potential was measured first, and after the potential stabilized, a Tafel curve was measured. The voltage range was set from -1.5V to +2V, and the scan rate was 1mV / s.

[0049] Figure 1 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC, Comparative Example 1 prepared (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 XRD spectra of V₂AlC, V₂AlC, Zr₂AlC, Ta₂AlC, and Nb₂AlC. It can be seen that the XRD spectra of V₂AlC, Zr₂AlC, Ta₂AlC, and Nb₂AlC confirm that V₂AlC has the P63 / mmc space group. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The formation of 2FeC single-phase solid solution; and (V 0.25 Nb0.25 Zr 0.25 Ta 0.25 Compared to 2AlC, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The substitution of Al atoms with Fe atoms in 2FeC does not change the crystal structure, as evidenced by almost identical XRD patterns.

[0050] Figure 2 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 SEM-EDS image of 2FeC. It can be seen that (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC exhibits the classic layered structure of the MAX phase, with clear layering visible at the micrometer scale. SEM-EDS energy dispersive spectroscopy reveals that the original high-entropy MAX phase powder is present within the high-entropy solid solution. Nanoscale translucent flakes of Fe2O3 are observed between the crystal structures within the layers, interconnected and also linking within the MAX phase layered structure, establishing electron channels and increasing the material's uniformity. These translucent flakes of Fe2O3 randomly occupy the interior of the MAX phase crystals, creating voids between materials. Combined with XRD phase composition analysis, this indicates that the prepared (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC is a typical MAX phase nanolayer structure, with its surface and interior randomly covered and connected by translucent sheet-like Fe2O3.

[0051] Figure 3 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The electromagnetic parameter relationship curves of M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti are shown, where a to c are curves showing the real part (ε'), imaginary part (ε'') of the dielectric constant and the loss tangent versus frequency, and d to f are curves showing the real part (μ'), imaginary part (μ”) of the permeability and the loss tangent versus frequency. The real and imaginary parts of the dielectric constant indicate the energy storage and attenuation capabilities of the high-entropy MAX phase material. Figure 3 (a) in (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25The real part ε' of the dielectric constant of both M2FeC and M2FeC-Ti shows a continuous decreasing trend, indicating that their energy storage capacity is not good; from Figure 3 (b) and (c) show more intuitively that (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The imaginary part ε₀ of the dielectric constant and the loss tangent tanε of M₂FeC-Ti are both in the negative region. This is because these materials contain free electrons, which, under the influence of an external electric field, induce a reverse polarization effect within the material, leading to a negative dielectric constant. This explains why (V₂FeC-Ti)₂FeC-Ti... 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The dielectric polarization ability of M2FeC and M2FeC-Ti is very poor, and the dielectric loss does not play a role in electromagnetic wave absorption.

[0052] The real part (μ') and imaginary part (μ”) of magnetic permeability represent the magnetic energy storage capacity and the magnetic energy dissipation capacity, respectively. Figure 3 (d) (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The μ' value of M2FeC continuously decreases in the frequency range of 1–9 GHz, and stabilizes at around 0.4 after 9–18 GHz. The μ' value of M2FeC-Ti also shows a continuous decreasing trend in the frequency range of 1–14 GHz, and stabilizes at around 0.4 after 9–18 GHz. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The magnetic energy storage capacity of M2FeC-Ti remained stable around 0.4, indicating that the magnetic energy storage capacity of both gradually decreases with increasing frequency. The magnetic energy storage capacity of M2FeC-Ti is greater than (V) in the low-frequency range. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC, both have the same storage capacity at high frequencies. Figure 3 In (e), at 1–7 GHz (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The μ value of M2FeC-Ti is greater than that of M2FeC-Ti, but M2FeC-Ti surpasses it after 7–18 GHz (V). 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC,(V 0.25 Nb 0.25 Zr0.25 Ta 0.25 M2FeC exhibits resonance peaks near both 3 GHz and 17 GHz. The former is due to natural resonance within the material, while the latter is due to exchange resonance. M2FeC-Ti, on the other hand, shows only one resonance peak near 6 GHz, indicating the presence of natural resonance within the M2FeC-Ti material. The loss tangent (tanμ) represents the dielectric's ability to absorb transmitted electromagnetic waves. Figure 3 (f) It can be seen that before 11 GHz (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The magnetic loss capability of M2FeC is stronger than that of M2FeC-Ti, and after 11 GHz, the magnetic loss capability of M2FeC-Ti is stronger.

[0053] Figure 4 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 CO curves of M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 1. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The CO values ​​of M2FeC and M2FeC-Ti showed significant and strong fluctuations in the measurement frequency. Specifically, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The strong resonance peak of M2FeC at 9 GHz, followed by stabilization after 14 GHz, indicates that turbine losses dominate magnetic losses after 14 GHz. The stable C0 curve of M2FeC-Ti before 7 GHz indicates that turbine losses dominate magnetic losses before this point. The appearance of a resonance peak after this point indicates that turbine losses no longer dominate magnetic losses. Based on the previous explanation, natural resonance should now be the dominant factor for magnetic losses. In conclusion, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The electromagnetic wave absorption capability of M2FeC and M2FeC-Ti is dominated by magnetic loss, among which (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The magnetic loss of M2FeC is dominated by natural resonance, exchange resonance and turbine loss, while the magnetic loss of M2FeC-Ti is dominated by natural resonance and turbine loss.

[0054] Figure 5 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 2 are all different types of FeC-Ti. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The reflection loss (RL) curves (a, c, e) and 2D contour lines (b, d, f) of 2AlC are shown. Figure 5 (ab) and Figure 5 (ef) It can be seen that in Example 1, after replacing Al with Fe in the high-entropy MAX phase, the electromagnetic wave absorption capability was effectively enhanced compared to Comparative Example 2, the bandwidth was broadened, and the absorption thickness was reduced. From Figure 5 (a) It can be seen that (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 By selecting an appropriate absorber thickness within the research frequency range (1–18 GHz), 2FeC can achieve 90% effective absorption across the entire frequency band (reflection loss < -10 dB). At a thickness of 1.5 mm, it exhibits two absorption peaks and a minimum reflection loss value (RL). min The minimum reflection loss (RL) is -43.7 dB (6.27 GHz) at a thickness of 1.0 mm. min The value is -33.48 dB; from Figure 5 (b) It can be seen that when the thickness is 1.5 mm, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The maximum effective absorption bandwidth of 2FeC is 13 GHz (2.9–15.9 GHz), which covers the C-Ku band. Even at -20 dB (effective absorption reaches 99%), it still exhibits good absorption capabilities with thicknesses of 1.5 mm and 1.0 mm, and the effective absorption bandwidth at 1.5 mm thickness can still reach 9.3 GHz (4.5–13.8 GHz). Figure 5 (c) It can be seen that when the thickness of M2FeC-Ti is 1.0 mm, the minimum reflection loss value (RL) is... min The value is -33.10 dB, from Figure 5 (d) It can be seen that, with a thickness of 1.5 mm, M2FeC-Ti exhibits an effective absorption of <-10 dB in the wavelength range above 4.1 GHz. Although the absorption range is relatively wide, it is still relatively low compared to (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25)2FeC has a higher effective absorption frequency range. In summary, it can be seen that compared to comparative examples 1-2, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2FeC has a stronger ability to absorb electromagnetic waves, especially in the low frequency range (2-8GHz).

[0055] Having strong absorption capacity is not the only indicator for evaluating the overall wave absorption capacity of a material. The principle of impedance matching is to minimize reflected waves by maximizing the energy absorbed inside the material. Figure 6 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 2 are all different types of FeC-Ti. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The impedance matching (a, c, e) and 2D contour lines (b, d, f) of 2AlC are shown. The optimal impedance matching range is generally set between 0.8 and 1.2. Figure 6 The area enclosed by the black dashed line and the red solid line in (b, d, f) can be used to evaluate the impedance matching capability of the material. Figure 6 It can be seen from (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC is more compatible with M2FeC-Ti and (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC has a larger matching impedance area and better impedance matching, which may be related to the reduction of the complex permittivity, which can promote the electromagnetic waves to enter the absorber to the maximum extent and reduce reflection.

[0056] As can be seen from the electrochemical corrosion mechanism, on a thermodynamic scale, the self-corrosion potential E of a material is... corr The E of the material is inversely proportional to the trend of material corrosion. corr The larger the value, the less likely corrosion will occur; conversely, the smaller the value, the less likely corrosion will occur. corr The smaller the value, the greater the tendency for corrosion. From a kinetic perspective, the material's self-corrosion current density i corr The corrosion rate is directly proportional to the self-corrosion current density of the material; the higher the self-corrosion current density, the greater the corrosion rate, and vice versa. corr The smaller the value, the lower the corrosion rate.

[0057] Figure 7 (V) prepared in Example 1 0.25 Nb0.25 Zr 0.25 Ta 0.25 Polarization curves of M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in 5% HCl solution. It can be seen that the trends and potential magnitudes of the two are similar. Specifically, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 After passing through the activation region, M2FeC and M2FeC-Ti directly enter the stable passivation region, forming a passivation film with good corrosion resistance on the material surface. The current density is almost independent of the electrode potential. The passivation potential E... p The values ​​are 0.293V and 0.456V respectively, at which point the passivation current density i p 407.18 mA / cm 2 and 419.44 mA / cm 2 The stable passivation state persisted until the end of the test. Since the material contains Fe atoms, it is hypothesized that a valence state change occurred in the activated region: Fe → Fe. 2+ +2e - A more stable state is formed in the passivation region: 2Fe + H₂O → Fe₂O₃ + 6H₂O + +6e - .

[0058] Table 1 shows the (V) prepared in Example 1. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 2 are all different types of FeC-Ti. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The electrochemical corrosion parameters of Al2C in 5% HCl solution show that (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The self-corrosion potential E of )2AlC and M2FeC-Ti corr The values ​​are not significantly different, at -0.254V and -0.265V respectively, both greater than (V). 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC, self-corrosion current density i corr 0.323 mA / cm 2 and 0.481 mA / cm 2 In contrast, (V) 0.25 Nb 0.25 Zr0.25 Ta 0.25 )2AlC has a lower corrosion rate in 5% HCl solution.

[0059] Figure 8 (V) prepared in Example 1 0.25 Nb 0.25 Zr 0.25 Ta 0.25 Polarization curves of M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti in 5% NaOH solution. It can be seen that M2FeC-Ti is more polarized than (V... 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The self-corrosion potential of M2FeC shifts to the right, meaning the self-corrosion potential value increases. M2FeC-Ti and (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The anolyte branch of 2FeC exhibited different corrosion behavior at high potentials. This can be seen from the figure (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC passes through the passivation potential (E) after the activation region p After reaching 0.047), it directly entered the stable passivation region, with a passivation current density i p =0.0281mA / cm 2 During this period, a dense passivation film with good corrosion resistance is formed, which can effectively prevent direct contact between the material and the corrosive liquid. tp At 0.465V, the polarization curve begins to enter the passivation region. After this, it is observed that it is about to enter the second passivation region around 1.25V. This can be considered as E... p2 =1.25V is the second passivation potential. M2FeC-Ti also passes through a passivation potential (E) after the activation region. p After reaching 0.112), it directly enters the stable passivation region, with a passivation current density i. p =0.0121mA / cm 2 In E tp At 0.486V, the polarization curve begins to enter the overpassivation region, and the current density increases continuously with the increase of potential, indicating that M2FeC-Ti re-enters the activation region after the overpassivation potential and does not generate a passivation film again within 2V.

[0060] Table 2 shows the (V) prepared in Example 1. 0.25 Nb 0.25 Zr 0.25 Ta 0.25M2FeC-Ti prepared in Comparative Example 1 and M2FeC-Ti prepared in Comparative Example 2 are all different types of FeC-Ti. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The electrochemical corrosion parameters of Al2C in 5% NaOH solution show that (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC, M2FeC-Ti and (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The self-corrosion potential E of 2AlC corr The values ​​are -0.159V, -0.055V, and -0.043V respectively, indicating that M2FeC-Ti and (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC is more prone to corrosion; (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC, M2FeC-Ti and (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The self-corrosion current density i of 2AlC corr They are 0.00824 mA / cm 2 0.0113 mA / cm 2 and 0.0217mA / cm 2 This illustrates (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2FeC has a lower corrosion rate and better corrosion resistance than M2FeC-Ti and (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC is better.

[0061] Table 1

[0062] <![CDATA[(V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC]]> -0.254 0.323 <![CDATA[M2FeC-Ti]]> -0.265 0.481 <![CDATA[(V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC]]> -0.231 0.335

[0063] Table 2

[0064] <![CDATA[(V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC]]> -0.159 0.00824 <![CDATA[M2FeC-Ti]]> -0.055 0.0113 <![CDATA[(V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC]]> -0.043 0.0217

[0065] Example 2

[0066] A method for preparing a high-entropy MAX phase material includes the following steps:

[0067] Step 1: Using a molar ratio of V:Nb:Zr:Ta:Al:C = 0.5:0.5:0.5:0.5:1.1:1, vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder are placed in an agate mortar. An appropriate amount of anhydrous ethanol is added, and the mixture is ground and mixed for 30 minutes. After vacuum drying at 80℃ for 12 hours, the mixed powder is transferred to an alumina boat, which is then placed in a tube furnace and sintered under an argon atmosphere. The temperature is increased to 1600℃ at a rate of 5℃ / min, held for 180 minutes, and then naturally cooled to room temperature under an argon atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC;

[0068] Step 2, (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC and 50wt% ethanol solution were mixed and stirred evenly, then irradiated in an electron beam environment for 30 min at an electron beam irradiation dose rate of 200 Gy / min. After vacuum drying at 80℃ for 24 h, the pretreated (V) was obtained. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC, then ground and mixed with ferrous chloride and potassium chloride for 30 min, the mixed powder was transferred to an alumina boat, and the alumina boat was placed in a tube furnace for sintering under an argon atmosphere: the temperature was increased to 650℃ at a heating rate of 5℃ / min, held for 420 min, and then naturally cooled to room temperature under an argon atmosphere. It was ground until fine, soaked in deionized water for 2 h, washed three times with water, and dried at 60℃ for 24 h to obtain the high-entropy MAX phase material (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC; where, (Ti 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 The molar volume ratio of 2AlC and ethanol solution is 1 mol: 800 mL, (Ti 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 The molar ratio of AlC, ferrous chloride and potassium chloride is 1:1.5:6.

[0069] Example 3

[0070] A method for preparing a high-entropy MAX phase material includes the following steps:

[0071] Step 1: Using a molar ratio of V:Nb:Zr:Ta:Al:C = 0.5:0.5:0.5:0.5:1.1:1, vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder are placed in an agate mortar. An appropriate amount of anhydrous ethanol is added, and the mixture is ground and mixed for 30 minutes. After vacuum drying at 80℃ for 12 hours, the mixed powder is transferred to an alumina boat, which is then placed in a tube furnace and sintered under an argon atmosphere. The temperature is increased to 1600℃ at a rate of 5℃ / min, held for 180 minutes, and then naturally cooled to room temperature under an argon atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC;

[0072] Step 2, (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC and 50wt% ethanol solution were mixed and stirred evenly, and then irradiated in an ultrasonic and electron beam environment for 30 min. The ultrasonic frequency was 60 kHz and the ultrasonic power was 400 W. The electron beam irradiation dose rate was 200 Gy / min. After vacuum drying at 80 °C for 24 h, the pretreated (V) was obtained. 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC, then grind and mix with ferrous chloride and potassium chloride for 30 min. Transfer the mixed powder to an alumina boat and place the alumina boat in a tube furnace for sintering under an argon atmosphere: heat to 650℃ at a heating rate of 5℃ / min, hold for 420 min, then cool naturally to room temperature under an argon atmosphere, grind, soak in deionized water for 2 h, wash three times, and dry at 60℃ for 24 h to obtain the high-entropy MAX phase material (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC; where, (Ti 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2 The molar volume ratio of 2AlC and ethanol solution is 1 mol: 800 mL, (Ti 0.2 V 0.2 Nb 0.2 Zr 0.2 Ta 0.2The molar ratio of AlC, ferrous chloride and potassium chloride is 1:1.5:6.

[0073] The electromagnetic wave absorption performance of the high-entropy MAX phase materials prepared in Examples 2 and 3 was tested. In Example 2, the RL absorption performance was [value missing] at 6.0 GHz and a thickness of 1.5 mm. min The effective absorption bandwidth of a 1.5mm thickness is -45.8dB at -20dB, and 10.9GHz at -20dB. Example 3 shows RL at 5.86GHz and a 1.5mm thickness. min The effective absorption bandwidth of a 1.5mm thickness is -47.2dB at -20dB, and 11.2GHz at -20dB. In Example 1, the RL at 6.27GHz and 1.5mm thickness is... min The effective absorption bandwidth of a 1.5mm thickness is -43.7dB at -20dB, and 9.3GHz at -20dB. It can be seen that the electromagnetic wave absorption performance of Examples 2 and 3 is improved compared to Example 1. This invention improves the absorption performance of electromagnetic waves in (V... 0.25 Nb 0.25 Zr 0.25 Ta 0.25 Electron beam irradiation pretreatment of AlC makes it easier for Fe to enter and replace Al, resulting in a product with stable structure and high crystallinity, which is beneficial to improving its microwave absorption ability. In Example 3, ultrasound was added during the electron beam irradiation process. Under the action of ultrasound, the electrons are more active, and the obtained (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The reaction between 2AlC and ferrous chloride is more effective, and the microwave absorption capability of the resulting high-entropy MAX phase material is further improved.

[0074] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A high-entropy MAX phase material, characterized in that, The chemical formula of the high-entropy MAX phase material is (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC; The high-entropy MAX phase material is prepared by the following method: Step 1: Vanadium powder, niobium powder, zirconium powder, tantalum powder, aluminum powder, and graphite powder are placed in an agate mortar, and anhydrous ethanol is added for grinding and mixing. After vacuum drying, the mixed powder is transferred to an alumina container, which is then placed in a tube furnace and sintered under an inert atmosphere. The mixture is then naturally cooled to room temperature under an inert atmosphere to obtain (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC; for the obtained (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC is preprocessed. The specific method of preprocessing is as follows: (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2AlC and 30-60wt% ethanol solution were mixed and stirred evenly, and then irradiated in an ultrasonic and electron beam environment for 20-40 min. The ultrasonic frequency was 40-80 kHz and the ultrasonic power was 300-600 W. The electron beam irradiation dose rate was 180-250 Gy / min. After irradiation, the mixture was vacuum dried at 80℃ for 20-40 h to obtain the pretreated (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2AlC; Step 2: Pre-process (V) 0.25 Nb 0.25 Zr 0.25 Ta 0.25 2AlC, ferrous chloride, and potassium chloride were ground and mixed. The mixed powder was transferred to an alumina container and placed in a tube furnace for sintering under an inert atmosphere. The mixture was then naturally cooled to room temperature under an inert atmosphere, ground again, soaked in deionized water, washed, and dried to obtain the high-entropy MAX phase material (V). 0.25 Nb 0.25 Zr 0.25 Ta 0.25 )2FeC.

2. The high-entropy MAX phase material as described in claim 1, characterized in that, In step one, the grinding time is 20-40 minutes; the vacuum drying temperature is 70-90°C; and the drying time is 10-14 hours.

3. The high-entropy MAX phase material as described in claim 1, characterized in that, In step one, the sintering process is as follows: the temperature is increased to 1500-1700℃ at a heating rate of 4-6℃ / min, and held for 120-240min.

4. The high-entropy MAX phase material as described in claim 1, characterized in that, In step two, (V 0.25 Nb 0.25 Zr 0.25 Ta 0.25 The molar ratio of AlC, ferrous chloride and potassium chloride is 1:1.3~1.7:5~7.

5. A high-entropy MAX phase material as described in claim 1, characterized in that, In step two, the grinding time is 20-40 minutes; the sintering method is as follows: heat to 600-700℃ at a heating rate of 4-6℃ / min, and hold for 360-480 minutes.

6. A high-entropy MAX phase material as described in claim 1, characterized in that, In step two, the water is soaked in deionized water for 1-3 hours; washed 2-4 times; and dried at 50-70℃ for 20-28 hours.

7. A high-entropy MAX phase material as described in claim 1, characterized in that, In steps one and two, the inert atmosphere is argon.

8. An application of the high-entropy MAX phase material as described in any one of claims 1-7 in electromagnetic wave absorption.

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