Preparation method and application of iron-cobalt alloy carbon inlaid composite material

Abstract

The invention relates to the technical field of microwave absorption, and discloses a preparation method and application of an iron-cobalt alloy carbon inlaid composite material, the preparation method of the composite material comprises the following steps: S1, taking spinel type iron-cobalt alloy powder as a raw material, adding phenolic resin and a solvent for mixing, and then removing the solvent to obtain an iron-cobalt alloy / phenolic resin homogeneous mixture; s2, heating and curing the iron-cobalt alloy / phenolic resin homogeneous mixture, and then crushing and sieving the iron-cobalt alloy / phenolic resin homogeneous mixture to obtain iron-cobalt alloy inlaid phenolic resin particles; and S3, the material obtained in the S2 is subjected to high-temperature carbonization under the vacuum condition, and the iron-cobalt alloy carbon inlaid composite material is obtained. The FeCo-C / RGO / PLA wave-absorbing wire is prepared by further combining a fused deposition modeling technology, taking the particles as a wave-absorbing phase and compounding the particles with reduced graphene oxide (RGO) and polylactic acid (PLA). The obtained material has the characteristic of broadband absorption, and an innovative solution is provided for electromagnetic pollution treatment in the fields of 5G communication, military stealth and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of wave-absorbing materials, and in particular to a preparation method and application of an iron-cobalt alloy carbon-inlaid composite material. Background Art

[0002] Magnetic materials (such as Fe, Co, Ni, and their oxides) have attracted considerable attention due to their excellent magnetic loss properties. As a typical soft magnetic material, FeCo alloys exhibit excellent magnetic loss resistance due to their high saturation magnetization and high Curie temperature, remaining stable even at high temperatures. However, single FeCo alloy particles as absorbers suffer from drawbacks such as a single loss pattern, a narrow absorption bandwidth, and easy aggregation in the matrix, which limits their practical applications.

[0003] CN114073919A discloses carbon-magnetic metal-dispersed hollow composite microspheres, their preparation method, and applications. These microspheres comprise hollow carbon microspheres doped with metal and / or metal alloy particles. The composite of carbon and metal alloys achieves a combination of electrical and magnetic losses, resulting in good impedance matching and excellent electromagnetic wave absorption. However, the inventors' analysis revealed that this method for preparing the carbon-magnetic metal-dispersed hollow composite microspheres involves multiple chemical reactions of metal salts combined with physical methods such as carbonization, resulting in a complex process. Summary of the Invention

[0004] The present invention provides a preparation method and application of an iron-cobalt alloy carbon-inlaid composite material. Using spinel FeCo alloy particles as raw material, iron-cobalt alloy carbon-inlaid FeCo-C particles are obtained by inlaying carbon C in the structural gaps of the particles. The particles can increase the heterogeneous interface and the multiple reflections of electromagnetic waves therein, and can also be used as composite wires for 3D printing.

[0005] The technical solution of the present invention is to provide a method for preparing an iron-cobalt alloy carbon inlaid composite material, comprising the following steps: S1, using spinel iron-cobalt alloy powder as raw material, adding phenolic resin and solvent to mix, and then removing the solvent to obtain a homogeneous mixture of iron-cobalt alloy / phenolic resin; S2, heating and solidifying the homogeneous mixture of iron-cobalt alloy and phenolic resin, and then crushing and sieving it to obtain iron-cobalt alloy embedded phenolic resin particles; S3. Carbonizing the material obtained in S2 at high temperature under vacuum conditions to obtain an iron-cobalt alloy carbon inlaid composite material.

[0006] Optionally, the spinel iron-cobalt alloy powder has a particle size of 5 to 30 μm, the mass ratio of the iron-cobalt alloy powder to the phenolic resin is 1:0.3 to 1.5, and the Fe:Co ratio in the alloy powder is 50 wt%:50 wt% to 65 wt%:35 wt%.

[0007] Optionally, the solvent used in S1 is anhydrous ethanol, and the mixing time is 90 to 300 minutes, and the anhydrous ethanol evaporates after mixing.

[0008] Optionally, the curing temperature in S2 is 90° C. to 180° C., and the curing time is 90 to 240 minutes.

[0009] Optionally, during crushing in S2, the rotation speed is: 300~3000r / min; the total crushing time is 60min~120min, and the screen mesh size is 200~600 mesh during screening.

[0010] Optionally, during the carbonization treatment, the vacuum is evacuated to below -0.1 MPa, the temperature is raised at a rate of 50-150° C. to a carbonization temperature of 800-900° C., and the temperature is maintained for 6-12 hours.

[0011] The present invention also relates to an iron-cobalt alloy carbon-inlaid composite material obtained by the preparation method.

[0012] The present invention also relates to the use of the iron-cobalt alloy carbon inlaid composite material in the preparation of 3D printing absorbing materials.

[0013] In further applications, iron-cobalt alloy carbon inlaid composite material (FeCo-C), reduced graphene oxide (RGO) and polylactic acid (PLA) are mixed in a mass ratio of 10~40:0~6:90~54 and ball-milled into powder; then the powder is melt-extruded at high temperature into 3D printed absorbing wire, which is printed and formed as 3D printer consumables.

[0014] Optionally, during high-temperature melt extrusion, the temperature of zone 1 is controlled at 155-170°C, the temperature of zone 2 is controlled at 155-135°C, the temperature of zone 3 is controlled at 135-120°C, the water tank temperature is 15-20°C, the screw speed is 15-20r / min, and the traction frequency conversion speed is 8-12r / min; the parameters of the 3D printing process are that the print head adopts a 0.4mm-0.6mm nozzle size, the nozzle temperature is 185-205°C, the base plate temperature is 50-65°C, the printing speed is 20-32mm / s, the fan speed is 100-200r / min, and the printing layer height is 0.1-0.2mm.

[0015] The present invention has the following beneficial effects: 1. The present invention uses spinel FeCo powder as raw material, mixes it with phenolic resin, solidifies, crushes it, and then carbonizes it at high temperature. This achieves carbon black embedded in the FeCo gap and coated on the FeCo surface at the same time, successfully preparing FeCo-C composite particles. The regular wrinkled carbon shell on the FeCo surface effectively extends the propagation path of electromagnetic waves and triggers multiple reflections. At the same time, the internal filling effect of carbon black constructs a variety of heterogeneous interfaces such as FeCo@C, FeCo-PLA, and PLA-C in the composite material. These heterogeneous interfaces can enhance the interfacial polarization effect, thereby improving the material's attenuation ability for electromagnetic waves. At the same time, the preparation, solidification, carbonization and crushing of the composite particles of the present invention are physical means, the process is highly controllable, and the preparation process time is shortened.

[0016] 2. This invention also combines FeCo-C composite particles with reduced graphene oxide (RGO) to produce 3D-printable absorbing filaments. The carbon inlay synergizes with the addition of RGO graphene to introduce dielectric loss. Simultaneously, the FeCo-C composite particles embedded in the iron-cobalt alloy carbon also mitigate the impedance mismatch caused by the high conductivity of graphene. This absorbing filament uses polylactic acid (PLA) as a matrix, which improves mechanical properties and protects the FeCo-C composite particles. The material is also environmentally friendly and biodegradable. The material provided by this invention is used in 3D printing, facilitating the secondary development of absorbing materials to address various electromagnetic wave pollution environments.

[0017] 3. The 3D-printed absorbing wire obtained by the present invention exhibits excellent absorption performance. When the RGO content is 5 wt% and the FeCo@C particle content is 30 wt%, the composite material exhibits an effective absorption bandwidth of 5.68 GHz and a reflection loss of -19.67 dB at a thickness of 1.6 mm. This is attributed to the synergistic effect of polarization loss and conductivity loss in the high-frequency band, which broadens the absorption bandwidth under these concentration and thickness conditions. When the graphene content is 1 wt% and the composite material is 5 mm thick, it can effectively absorb 31.7% of the bandwidth of the 5G NR low-frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The following are the SEM images of the raw material FeCo iron-cobalt alloy powder in Example 1 (a); the SEM images of the FeCo-C prepared in Example 1 (b), (c), and (e); the content of each element in the FeCo-C particles prepared in Example 1 (d); and the distribution of each element in the FeCo-C in Example 1 (f), (g), and (h).

[0019] Figure 2 This is the XRD pattern of FeCo-C / RGO / PLA absorbing wire. The wire is abbreviated as FR0~FR5, and the number is the mass percentage of RGO.

[0020] Figure 3This is the actual FeCo-C / RGO / PLA absorbing wire (FR5) with an RGO mass fraction of 5wt%.

[0021] Figure 4 Electromagnetic parameters of FeCo-C / RGO / PLA absorbing wires (FR0~5) with RGO mass fraction of 0~5wt%, (a) real part of dielectric constant; (b) imaginary part of dielectric constant; (c) tangent of dielectric constant; (d) real part of magnetic permeability; (e) imaginary part of magnetic permeability; (f) tangent of magnetic permeability.

[0022] Figure 5 Reflection loss and three-dimensional projection of FeCo-C / RGO / PLA absorbing wire (FR0) without adding graphene RGO.

[0023] Figure 6 Reflection loss and three-dimensional projection of FeCo-C / RGO / PLA absorbing wire (FR1) with a graphene RGO mass fraction of 1wt%.

[0024] Figure 7 Reflection loss and three-dimensional projection of FeCo-C / RGO / PLA absorbing wire (FR2) with a graphene RGO mass fraction of 2wt%.

[0025] Figure 8 Reflection loss and three-dimensional projection of FeCo-C / RGO / PLA absorbing wire (FR3) with a graphene RGO mass fraction of 3wt%.

[0026] Figure 9 Reflection loss and three-dimensional projection of FeCo-C / RGO / PLA absorbing wire (FR4) with a graphene RGO mass fraction of 4wt%.

[0027] Figure 10 Reflection loss and three-dimensional projection of FeCo-C / RGO / PLA absorbing wire (FR5) with a graphene RGO mass fraction of 5wt%. DETAILED DESCRIPTION

[0028] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials used in the following examples are commercially available products unless otherwise specified. The embodiments of the present invention will be described in detail below with reference to the examples. However, it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention.

[0029] Example 1: The present invention provides a method for preparing an iron-cobalt alloy carbon inlaid composite material and its application in 3D printing absorbing wires. The main steps are as follows: Step 1: Prepare FeCo alloy powder (Fe:Co ratio:65wt%:35wt%) with a particle size of 5-15μm, PF phenolic resin (PF) with a purity of greater than 99%, PLA (polylactic acid) with a purity of greater than 99%, and analytical grade anhydrous ethanol. Place the PLA powder in a constant temperature forced air drying oven at 50°C and dry it for 10 hours.

[0030] Step 2: Mix 25 g of FeCo alloy powder, 10 g of phenolic resin and 50 g of alcohol, and stir mechanically at a speed of 900 r / min for 90 minutes. During the stirring process, the degree of alcohol volatilization is judged according to the fluidity of the mixture. During the process, add alcohol in three times, a total of 100 g, until the alcohol is completely evaporated and the mixture becomes black and viscous.

[0031] Step 3: Place the mixture in an oven at 110° C. and bake for 20 minutes, then raise the temperature to 160° C. and maintain for 60 minutes to obtain a FeCo-PF iron-cobalt alloy resin mixed solid.

[0032] Step 4: The solid was broken into pieces and further crushed for 1 hour, and sieved through a 325-mesh sieve to obtain phenolic resin-embedded iron-cobalt alloy powder.

[0033] Step 5: The obtained powder is placed in a nitrogen atmosphere and carbonized at 900° C. for 8 hours to prepare FeCo-C particles.

[0034] Step 6: Weigh FeCo-C and PLA in a mass ratio of 3:7, and prepare a 100g mixed powder. Place the mixed powder in a ball mill jar and add an equal mass of zirconium dioxide grinding balls. Use a horizontal planetary ball mill and mill at 350 rpm for 4 hours to obtain a FeCo-C / PLA composite powder.

[0035] Step 7: The resulting FeCo-C / PLA composite powder was processed through a melt-molding extruder to produce 3D printing filament with a diameter of 1.75 ± 0.05 mm. The key extruder parameters were: screw stage 1, screw stage 2, and nozzle temperatures of 150°C, 155°C, and 160°C, respectively, and a cooling water temperature of 30°C.

[0036] Step 8: Use a 3D printer to print the composite filament into a coaxial ring with dimensions of 7.00 mm OD, 3.04 mm ID, and 2.50 mm height. The composite's electromagnetic parameters are tested using the coaxial method. Key 3D printing parameters are: print temperature of 190°C, bed temperature of 70°C, layer height of 0.1 mm, infill density of 100%, and print speed of 25 mm / s.

[0037] Step 9: Characterize the micromorphology of FeCo and FeCo@C microspheres by SEM, and characterize the element distribution of FeCo@C by EDS. Figure 1 Through the sol-carbonization process, carbon black was successfully embedded in the gaps of FeCo and coated on the FeCo surface to form a wrinkled carbon shell.

[0038] The phase composition and crystal structure of FeCo-C / RGO / PLA (FR0) composite wire were analyzed by X-ray diffractometer (XRD). Figure 2 Curve FR0. The electromagnetic parameters of the composite coaxial ring in the frequency range of 2~18 GHz are measured using a vector network analyzer and plotted as follows: Figure 4 FR0 curve. Each component in the composite wire did not undergo chemical changes, and the crystal composition did not change. The diffraction peaks of PLA were observed at 2θ=19.6° and 22.6°, corresponding to the (203) (210) crystal planes; the diffraction peaks of FeCo were detected at 2θ=44.8°, 65.2° and 82.5°, corresponding to the (110) (200) (211) crystal planes; the diffraction peaks of Co were observed at 2θ=51.5° and 75.9°, corresponding to the (200) and (220) crystal planes; the diffraction peak of C was observed at 2θ=22.7° (covered by the PLA diffraction peak), corresponding to the (120) crystal plane. In addition, a small amount of Co diffraction peaks were observed in the spectrum. This may be because the FeCo alloy powder was prepared by atomization. The melting points of Fe and Co are 1538°C and 1495°C, respectively, and the difference between the two is small. However, during the atomization process, due to the extremely fast cooling rate of the metal melt, Co may solidify before Fe, resulting in premature precipitation of Co in local areas, resulting in the presence of a small amount of elemental Co powder. Based on the transmission line theory, the reflection loss of the composite material under different thickness conditions was calculated and the reflection loss curve and mapping diagram were drawn as shown in the figure. Figure 5 When the composite wire does not contain graphene, the material's electromagnetic absorption loss is almost entirely dependent on the 30wt% FeCo@C particles, which can achieve an effective absorption bandwidth of 2.64GHz (2.5mm).

[0039] Example 2 The present invention provides a method for preparing an iron-cobalt alloy carbon inlaid composite material and its application in 3D printing absorbing wires: Step 1: Prepare FeCo alloy powder with a purity greater than 99% and a particle size of 5-15 μm; RGO graphene with a purity greater than 99%; PF phenolic resin with a purity greater than 99%; PLA polylactic acid with a purity greater than 99%; and analytical grade anhydrous ethanol. Place the PLA powder in a constant temperature forced air drying oven at 50°C and dry it for 10 hours.

[0040] Step 2: Mix 25 g of FeCo alloy powder, 15 g of phenolic resin, and 50 g of alcohol, and stir mechanically at 900 r / min for 90 minutes. During stirring, gradually add 100 g of alcohol in three portions until the mixture becomes black and viscous.

[0041] Step 3: Place the mixture in an oven at 110° C. and bake for 20 minutes, then raise the temperature to 160° C. and maintain for 60 minutes to obtain a FeCo-PF iron-cobalt alloy resin mixed solid.

[0042] Step 4: The solid was broken into pieces and further crushed for 1.5 hours, and sieved through a 200-mesh sieve to obtain phenolic resin-embedded iron-cobalt alloy powder.

[0043] Step 5: The obtained powder is placed in a nitrogen atmosphere and carbonized at 900° C. for 10 hours to prepare FeCo-C particles.

[0044] Step 6: Weigh RGO, FeCo-C, and PLA in mass ratios of 30:1:69, 30:2:68, 30:3:67, 30:4:66, and 30:5:65, respectively. Five mixed powders were placed in ball mills with equal weights of zirconium dioxide grinding balls. Milling was performed using a horizontal planetary ball mill at 350 rpm for 4 hours. Repeat this process multiple times to obtain five sufficient RGO / FeCo-C / PLA composite powders, labeled RF1, RF2, RF5, and RF6.

[0045] Step 7: The five groups of RGO / FeCo-C / PLA composite powders were processed through a melt molding extruder to produce 3D printing filaments with a diameter of 1.75±0.05 mm. The key parameters of the extruder are: the temperatures of the first screw section, the second screw section, and the nozzle are 155°C, 160°C, and 170°C respectively, and the cooling water temperature is 30°C. The FeCo-C / RGO / PLA (FR5) composite filaments are as follows: Figure 3 .

[0046] Step 8: Use a 3D printer to print the composite filament into a coaxial ring with dimensions of 7.00 mm OD, 3.04 mm ID, and 2.50 mm height. The composite's electromagnetic parameters are tested using the coaxial method. Key 3D printing parameters are: print temperature of 200°C, bed temperature of 70°C, layer height of 0.1 mm, infill density of 100%, and print speed of 20 mm / s.

[0047] Step 9: Use X-ray diffractometer (XRD) to analyze the phase composition and crystal structure of the composite material. Figure 2 , A vector network analyzer was used to measure the electromagnetic parameters of the composite coaxial ring in the frequency range of 2~18 GHz, and the reflection loss of the composite material under different thickness conditions was calculated based on the transmission line theory. Figure 4 Based on the transmission line theory, the reflection loss of RF1~RF5 composite materials under different thickness conditions is calculated to draw the reflection loss curve and mapping diagram as shown in the figure. Figures 6 to 10 When the graphene addition amount is 1-5wt%, the effective absorption bandwidth of the FeCo@C / RGO / PLA composite wire can reach above 4.3GHz (2mm). Among them, when the graphene addition amount is 5wt%, the effective absorption bandwidth of the FeCo@C / RGO / PLA composite material reaches 5.68GHz, and the reflection loss at this time reaches a maximum of -19.67dB. In addition, this group of composite materials can achieve effective absorption of electromagnetic waves in the 3.6-18GHz frequency band by adjusting the thickness from 2.5mm to 5mm.

[0048] Both Example 1 and Example 2 optimize the absorption performance of composite wires by regulating the single absorption mechanism and impedance mismatch problem of FeCo alloy. Example 1 modifies FeCo alloy by sol-carbonization method, which is essentially to compound carbon black inside and on the surface of FeCo particles, thereby introducing dielectric properties to regulate impedance. While Example 2 is based on the electromagnetic parameters of Example 1 ( Figure 4 a~c show that the dielectric parameter level is low). Continuing to dope dielectric materials to improve the dielectric loss mechanism further broadens the effective absorption bandwidth. The effect is obvious. Figure 5 and Figure 10 , widening the effective absorption bandwidth from 2.64GHz to 5.68GHz.

[0049] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A method for preparing an iron-cobalt alloy carbon inlaid composite material, characterized in that: The following steps are involved: S1, using spinel iron-cobalt alloy powder as a raw material, adding phenolic resin and a solvent to mix, and then removing the solvent to obtain an iron-cobalt alloy / phenolic resin homogeneous mixture; S2, heating and solidifying the homogeneous mixture of iron-cobalt alloy and phenolic resin, and then crushing and sieving it to obtain iron-cobalt alloy embedded phenolic resin particles; S3. Carbonizing the material obtained in S2 at high temperature under vacuum conditions to obtain an iron-cobalt alloy carbon inlaid composite material.

2. The preparation method according to claim 1, wherein: The particle size of the spinel iron-cobalt alloy powder is 5-30 μm; the mass ratio of the iron-cobalt alloy powder to the phenolic resin is 1:0.3-1.

5.

3. The preparation method according to claim 1, wherein: The solvent used in S1 is anhydrous ethanol, and the mixing time is 90 to 300 minutes. After mixing, the anhydrous ethanol evaporates.

4. The preparation method according to claim 1, wherein: The curing temperature in S2 is 90°C~180°C, and the curing time is 90~240min.

5. The preparation method according to claim 1, wherein: During crushing in S2, the rotation speed is: 300~3000r / min; the total crushing time is 60min~120min, and the screen size for screening is 200~600 mesh.

6. The preparation method according to claim 1, wherein: During the carbonization treatment, the vacuum is evacuated to below -0.1MPa, and the carbonization temperature is reached at 800-900℃ at a heating rate of 50-150℃, and kept warm for 6-12h.

7. The iron-cobalt alloy carbon-inlaid composite material obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the iron-cobalt alloy carbon inlaid composite material according to claim 7 in the preparation of 3D printing absorbing materials.

9. The use according to claim 8, characterized in that: When preparing the absorbing material, iron-cobalt alloy carbon inlaid composite material (FeCo-C), reduced graphene oxide (RGO) and polylactic acid (PLA) are mixed in a mass ratio of 10~40:0~6:90~54 and ball-milled into powder; then the powder is melt-extruded at high temperature to form 3D-printed absorbing wire, which is printed and formed as a 3D printer consumable.

10. The use according to claim 9, characterized in that: During high-temperature melt extrusion, the temperature control zone 1 is 155-170°C, the temperature control zone 2 is 155-135°C, the temperature control zone 3 is 135-120°C, the water tank temperature is 15-20°C, the screw speed is 15-20r / min, and the traction frequency conversion speed is 8-12r / min; the parameters of the 3D printing process are: the print head uses a 0.4mm-0.6mm nozzle size, the nozzle temperature is 185-205°C, the base plate temperature is 50-65°C, the printing speed is 20-32mm / s, the fan speed is 100-200r / min, and the printing layer height is 0.1-0.2mm.

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