Heterogeneous fiber composite material with electromagnetic shielding and microwave absorption functions and preparation method thereof
The heterogeneous fiber composite material composed of graphitized carbon fiber modified with Cu-Co bimetallic oxide and paraffin wax has solved the integration problem of electromagnetic shielding and microwave absorption functions, and achieved effective microwave absorption and electromagnetic shielding in the 2-18GHz range, meeting the needs of small integrated instruments and equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies cannot simultaneously achieve effective electromagnetic shielding and microwave absorption functions in the same sample. Traditional methods struggle to balance the contradiction between strong and low reflection, leading to difficulties in functional integration.
A heterogeneous fiber composite material composed of graphitized carbon fibers modified with Cu-Co bimetallic oxide and paraffin wax can achieve both electromagnetic shielding and microwave absorption functions by controlling the ratio of Cu-Co bimetallic oxide to paraffin wax and the preparation method.
It achieves effective microwave absorption and electromagnetic shielding in the 2-18GHz range, with good frequency band coverage and absorption bandwidth, meeting the needs of small integrated instruments and equipment.
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Figure CN121801336A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of composite materials, in particular to a heterogeneous fiber composite material with electromagnetic shielding and microwave absorption functions and a preparation method thereof. BACKGROUND
[0002] With the rapid development of electronic technology, the wide application of microwave technology poses a threat to the reliability of equipment and information security. To solve the problem of electromagnetic interference and electromagnetic radiation safety, developing multifunctional electromagnetic attenuation materials is an important strategic task. Electromagnetic attenuation materials include electromagnetic interference shielding materials and microwave absorption materials. Simultaneously realizing electromagnetic shielding and microwave absorption functions is an inevitable development trend for developing small integrated instruments and equipment. The development of multifunctional materials can avoid the stacking of multiple layers, reduce weight, and save space.
[0003] Traditionally, the physical mechanisms of electromagnetic interference shielding and microwave absorption are mutually contradictory. Electromagnetic shielding mainly relies on strong electromagnetic wave reflection caused by high electrical conductivity, while microwave absorption requires extremely low electromagnetic wave reflection. Balancing "strong reflection" and "low reflection" is a difficulty in functional integration. According to the integrity of the electrical conductivity network, changing the filling concentration of the filler in the matrix can achieve electromagnetic shielding at high concentration and microwave absorption at low concentration, but it is very difficult to simultaneously achieve effective electromagnetic shielding and microwave absorption performance at the same concentration in the same sample, which requires careful design of material microstructure and components, taking into account both the impedance matching characteristics of microwave materials and the high-efficiency attenuation characteristics of shielding materials, which is extremely challenging. Therefore, it is very urgent to develop electromagnetic materials with electromagnetic shielding and microwave absorption functions. SUMMARY
[0004] To achieve the above purpose, the present application aims to provide a heterogeneous fiber composite material and a preparation method thereof, which has both electromagnetic shielding and microwave absorption functions.
[0005] In one aspect, the present application provides a heterogeneous fiber composite material with both electromagnetic shielding and microwave absorption functions.
[0006] The heterogeneous fiber composite material provided by the present application is composed of Cu-Co bimetallic oxide modified graphitized carbon fiber and paraffin.
[0007] In one embodiment of the present application, the mass ratio of the Cu-Co bimetallic oxide modified graphitized carbon fiber to paraffin is 3:7.
[0008] In one embodiment of the present application, the molar ratio of Cu ions to Co ions is 1:2.
[0009] In one embodiment of the present application, the thickness of the heterogeneous fiber composite material is 1.5 mm-3.0 mm.
[0010] In an embodiment of the present application, the Cu-Co bimetallic oxide modified graphitized carbon fiber is a graphitized carbon fiber with Cu-Co bimetallic oxide nanoparticles growing on the surface thereof.
[0011] In an embodiment of the present application, the mass ratio of carbon to Cu-Co bimetallic oxide in the heterogeneous fiber composite is 173:27.
[0012] In an embodiment of the present application, the length of the graphitized carbon fiber is in millimeter level and the diameter is in micrometer level.
[0013] Another aspect of the present application provides a method for preparing a heterogeneous fiber composite.
[0014] The method for preparing a heterogeneous fiber composite provided by the present application comprises: converting a solution containing Cu ions and Co ions into a solution containing copper hydroxide, cobalt hydroxide, basic copper carbonate and basic cobalt carbonate; immersing a carbon fiber felt into the solution containing copper hydroxide, cobalt hydroxide, basic copper carbonate and basic cobalt carbonate to obtain a precursor; annealing the precursor in air at least 400℃ to obtain a Cu-Co bimetallic oxide modified graphitized carbon fiber; mixing and grinding the fragments of the Cu-Co bimetallic oxide modified graphitized carbon fiber with fragments of paraffin to obtain a Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite.
[0015] In an embodiment of the present application, the mass ratio of the Cu-Co bimetallic oxide modified graphitized carbon fiber to paraffin is 3:7.
[0016] In an embodiment of the present application, the molar ratio of the Cu ions to Co ions is 1:2.
[0017] In an embodiment of the present application, the carbon fiber felt is immersed in the solution containing copper hydroxide, cobalt hydroxide, basic copper carbonate and basic cobalt carbonate for 30 minutes.
[0018] In an embodiment of the present application, the density of the carbon fiber felt is 0.1 g / m 3 , and the thickness is 3 mm, and the resistance in the thickness direction is <5 mW after the 64 mm thick carbon fiber felt is compressed to 85% of the original thickness.
[0019] The heterogeneous fiber composite provided by the present application has both electromagnetic shielding and microwave absorption functions. BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.
[0021] The present application can be more clearly understood with reference to the following detailed description in conjunction with the accompanying drawings, in which: Figure 1 Fig. 1 shows the Cu-Co bimetallic oxide modified graphitized carbon fiber prepared in Example 1, which is flexible and can be bent repeatedly. Figure 1 Fig. 2 shows the scanning electron microscope (SEM) images of the Cu-Co bimetallic oxide modified graphitized carbon fiber, which is flexible and can be bent repeatedly. Figure 1 It can be seen that the length of the graphitized carbon fiber is up to millimeter level, the average diameter is about 9 um, and Cu-Co bimetallic oxide nanoparticles grow on the surface of the carbon fiber, with an average diameter of about 150 nm.
[0022] Figure 2a Fig. 4 shows the Raman spectrum of the Cu-Co bimetallic oxide modified graphitized carbon fiber of Example 1 in the range of 130-900 cm-1. Five Raman peaks are located at 187, 457, 508, 601, and 658 cm-1, respectively. -1 -1 , which are typical vibration modes of Cu-Co spinel structure (A 1g +E g +3F 2g ), proving that the Cu-Co bimetallic oxide is in spinel structure. Among them, A 1g is derived from the breathing mode of (Cu 2+ -O) tetrahedron. F 2g (3) is derived from the coupling vibration of Cu 2+ -O-Co 3+ between the tetrahedral unit and the octahedral unit. F 2g (2) and Eg are derived from the asymmetric bending vibration and symmetric bending vibration of O-Co 3+ -O, respectively, while F 2g (1) mode is caused by the translational motion of Co 3+ ion in the octahedron.
[0023] Figure 2b Fig. 5 shows the Raman spectrum of the Cu-Co bimetallic oxide modified graphitized carbon fiber of Example 1 in the range of 800-2400 cm-1. The D peak is caused by the breathing mode of carbon ring caused by defects, and the G peak is the characteristic peak of graphitized carbon. -1 sp 2 The intensity ratio of D and G peaks (I I D / I G ) is 1.3, indicating that the carbon fiber contains graphitization structure and defects.
[0024] Figures 3a-3c The electromagnetic absorption and shielding performance characterization results of the Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material of Example 1 are shown.
[0025] Figure 4 The Fourier infrared spectra of the precursor and sample of Example 1 in the range of 950-450 cm -1 are shown.
[0026] Figure 5 The thermogravimetric curve of the Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material in an air atmosphere. As the temperature rises, the carbon is gradually oxidized and decomposed, and the weight of the sample continues to decrease. When the temperature reaches 800°C, the weight no longer changes, and the carbon has been completely consumed, leaving only Cu-Co bimetallic oxide. Therefore, the mass of carbon in the sample accounts for 86.5%, and Cu-Co bimetallic oxide accounts for 13.5%. DETAILED DESCRIPTION
[0027] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings.
[0028] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application or its application or uses.
[0029] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered part of the specification.
[0030] Example 1: Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material
[0031] Preparation of Cu-Co bimetallic oxide modified graphitized carbon fiber- paraffin composite The carbon fiber felt (density of 0.1 g / m 3, the 64 mm thick carbon fiber felt was compressed to 85% of the original thickness, and the resistance in the thickness direction was <5 mW) into small pieces of 2 cm x 1 cm, ultrasonic washing in anhydrous ethanol for 40 minutes, ultrasonic washing twice with deionized water, and then drying in an oven at 60°C for 24 hours. Then, 0.2013 g of Cu(NO3)2x3H2O and 0.4851 g of Co(NO3)2x6H2O (molar ratio / atomic number of Cu ions and Co ions is 1:2) were dissolved in 33.33 mL of deionized water, and 0.6006 g of urea (CO(NH2)2) and 0.2469 g of ammonium fluoride (NH4F) were added under magnetic stirring. After mixing well, the solution was transferred to a 50 ml polytetrafluoroethylene reaction kettle and reacted at 180°C for 10 hours, and then naturally cooled to room temperature. In the reaction kettle, Cu(NO3)2x3H2O and Co(NO3)2x6H2O reacted with urea and ammonium fluoride respectively, and the reaction product was a mixture of hydroxides and basic carbonates, including Cu(OH)2, Co(OH)2, Co2(OH)2CO3, Cu2(OH)2CO3 (as shown in Figure 4 ). The carbon fiber pieces after drying were immersed in the above solution for 30 minutes of ultrasonic. Then, the above sample was thoroughly washed with ethanol and ultrapure water, and dried in a 60°C oven for 24 hours. At this time, a "precursor" was obtained, which was a carbon fiber modified with Cu(OH)2+Co(OH)2+Co2(OH)2CO3+Cu2(OH)2CO3, as shown in Figure 4 . Finally, the precursor was annealed at 400°C in air for 2h at a heating rate of 5°C / min, to obtain a Cu-Co bimetallic oxide modified graphitized carbon fiber (as shown in Figure 4 ). Figure 4 In the precursor, -CO3 2- The corresponding peaks were located at 864 and 740 cm -1 The corresponding peaks of hydroxyl groups (M-OH) (M refers to metal Co and Cu) connected to Co and Cu were located at 542 cm -1 . In the sample, the peaks corresponding to -CO3 2- and M-OH disappeared, leaving only the peaks corresponding to Co-O and Cu-O, proving that the sample was a metal oxide containing Cu and Co.
[0032] The fragments of the Cu-Co bimetallic oxide modified graphitized carbon fiber prepared were mixed with paraffin fragments and ground to obtain a Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material, in which the mass ratio of the Cu-Co bimetallic oxide modified graphitized carbon fiber to paraffin was 3:7. The Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material was pressed into a coaxial ring with an inner diameter of 3 mm and an outer diameter of 7 mm, and a thickness of 2.2 mm.
[0033] Characterization of Cu-Co bimetallic oxide modified graphitized carbon fiber The prepared Cu-Co bimetallic oxide-modified graphitized carbon fibers are relatively soft and can recover their original shape after repeated bending. Figure 1 (a) and Figure 1 (b)).
[0034] The prepared Cu-Co bimetallic oxide-modified graphitized carbon fibers were analyzed using scanning electron microscopy (SEM). Figure 1 (c)- Figure 1 (e) It can be seen that the graphitized carbon fiber can reach the millimeter level in length and has an average diameter of about 9µm. Cu-Co bimetallic oxide nanoparticles with an average particle diameter of about 150nm are grown on the surface of the carbon fiber.
[0035] The prepared Cu-Co bimetallic oxide modified graphitized carbon fibers were analyzed using thermogravimetric analysis. Figure 5 Thermogravimetric curves of graphitized carbon fibers modified with Cu-Co bimetallic oxide in air atmosphere are shown. As the temperature increases, the carbon is gradually oxidized and decomposed, and the sample weight continuously decreases. When the temperature reaches 800℃, the weight no longer changes, indicating that the carbon has been completely consumed, leaving only Cu-Co bimetallic oxide. Therefore, carbon accounts for 86.5% of the mass of the sample, and Cu-Co bimetallic oxide accounts for 13.5%.
[0036] Electromagnetic absorption and shielding performance characterization The reflection loss (i.e., microwave absorption) and electromagnetic interference shielding effectiveness of a coaxial ring in the 2-18 GHz range were tested using a vector network analyzer. Figure 3a As shown, the Cu-Co bimetallic oxide-modified graphitized carbon fiber-paraffin composite material samples can simultaneously achieve effective microwave absorption and shielding functions in the 2-18 GHz range. The effective microwave absorption band (reflection loss < -10 dB) is 6.96-8.80 GHz, corresponding to an absorption bandwidth of 1.84 GHz, with a maximum reflection loss of -25.08 dB. The effective electromagnetic interference shielding band (shielding effectiveness > 10 dB) is 13.68-16.64 GHz, corresponding to a bandwidth of 2.96 GHz, with a maximum electromagnetic interference shielding effectiveness of 11.89 dB.
[0037] Example 2: Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material
[0038] The method for preparing the coaxial ring of Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material is the same as that for Example 1, except that the thickness of the coaxial ring is 1.8 mm.
[0039] Electromagnetic absorption and shielding performance characterization like Figure 3b As shown, the Cu-Co bimetallic oxide-modified graphitized carbon fiber-paraffin sample prepared in this embodiment can simultaneously achieve effective microwave absorption and shielding functions in the 2-18 GHz range. The effective microwave absorption band (reflection loss <-10 dB) is 8.72-11.44 GHz, corresponding to a 2.72 GHz absorption bandwidth, with a maximum reflection loss of -32.96 dB. The effective electromagnetic interference shielding band (shielding effectiveness >10 dB) is 13.84-15.36 GHz, corresponding to a 1.52 GHz bandwidth, with an electromagnetic interference shielding effectiveness maximum of 10.98 dB.
[0040] Example 3: Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material
[0041] Compared with Example 1, the method for preparing the coaxial ring of Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material in this embodiment is the same, except that the thickness of the coaxial ring is 2.6 mm.
[0042] Electromagnetic absorption and shielding performance characterization like Figure 3c As shown, the Cu-Co bimetallic oxide-modified graphitized carbon fiber-paraffin sample can simultaneously achieve effective microwave absorption and shielding functions in the 2-18 GHz range. The effective microwave absorption band (reflection loss <-10 dB) is 6.72-7.28 GHz, corresponding to an absorption bandwidth of 0.56 GHz, with a maximum reflection loss of -10.5 dB. The effective electromagnetic interference shielding bands (shielding effectiveness >10 dB) are 4.96-6.16 GHz and 13.28-18 GHz, corresponding to a bandwidth of 5.92 GHz, with an electromagnetic interference shielding effectiveness peak of 13.39 dB.
[0043] Comparative Example 1:
[0044] Compared with Example 1, the same preparation method was used, except that the mass ratio of Cu-Co bimetallic oxide-modified graphitized carbon fibers to paraffin was 1:9.
[0045] The coaxial ring in this comparative example has a minimum reflection loss of -3.32dB in the 2-18GHz range, and there is no effective microwave absorption frequency band (reflection loss <-10 dB), so it cannot simultaneously achieve electromagnetic shielding and microwave absorption functions.
[0046] Comparative Example 2:
[0047] Compared with Example 1, the same preparation method was used, except that the mass ratio of Cu-Co bimetallic oxide-modified graphitized carbon fibers to paraffin wax was 5:5.
[0048] The coaxial ring in this comparative example has a minimum reflection loss of -6.90dB in the 2-18GHz range, and there is no effective microwave absorption band (reflection loss <-10dB), so it cannot simultaneously achieve electromagnetic shielding and microwave absorption functions.
[0049] Comparative Example 3:
[0050] Carbon fiber felt was cut into 2cm × 1cm pieces, ultrasonically washed in anhydrous ethanol for 40 minutes, then ultrasonically washed twice with deionized water, and finally dried in an oven at 60°C for 24 hours. Next, 0.2013g of Cu(NO3)2×3H2O and 0.4851g of Co(NO3)2×6H2O were dissolved in 33.33mL of deionized water, and 0.6006g of urea (CO(NH2)2) and 0.2469g of ammonium bifluoride (NH4F) were added under magnetic stirring. After thorough mixing, the solution was transferred to a 50mL polytetrafluoroethylene reactor and reacted at 180°C for 10 hours, then naturally cooled to room temperature. The dried carbon fiber pieces were immersed in the above solution and ultrasonically washed for 30 minutes. Then, they were thoroughly washed with ethanol and ultrapure water, and dried in an oven at 60°C for 24 hours to obtain modified graphitized carbon fiber. Modified graphitized carbon fibers were mixed with paraffin wax at a mass ratio of 3:7 to obtain a modified graphitized carbon fiber-paraffin wax composite material. The modified graphitized carbon fiber-paraffin wax composite material was pressed into a coaxial ring with an inner diameter of 3 mm, an outer diameter of 7 mm, and a thickness of 2.2 mm. The coaxial ring in this comparative example has a minimum reflection loss of -38.41dB in the 2-18GHz range, corresponding to an effective absorption bandwidth of 1.6GHz. However, it does not have effective electromagnetic shielding (shielding effectiveness >10dB) and cannot simultaneously achieve electromagnetic shielding and microwave absorption functions.
[0051] The description in this application is given for illustrative purposes and is not intended to be exhaustive or to limit the application to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of this application and to enable those skilled in the art to understand this application and design various embodiments with various modifications suitable for a particular purpose.
Claims
1. A heterogeneous fiber composite material, characterized in that, The heterogeneous fiber composite material is composed of graphitized carbon fibers modified with Cu-Co bimetallic oxide and paraffin wax.
2. The heterogeneous fiber composite material according to claim 1, characterized in that, The mass ratio of the Cu-Co bimetallic oxide-modified graphitized carbon fiber to paraffin wax is 3:
7.
3. The heterogeneous fiber composite material according to claim 1, characterized in that, The Cu-Co bimetallic oxide modified graphitized carbon fiber is a graphitized carbon fiber with Cu-Co bimetallic oxide nanoparticles growing on its surface.
4. The heterogeneous fiber composite material according to claim 1, characterized in that, The molar ratio of Cu ions to Co ions in the Cu-Co bimetallic oxide is 1:
2.
5. The heterogeneous fiber composite material according to claim 1, characterized in that, The graphitized carbon fibers have a length in the millimeter range and a diameter in the micrometer range.
6. The heterogeneous fiber composite material according to claim 1, characterized in that, The mass ratio of carbon to Cu-Co bimetallic oxide in the heterogeneous fiber composite material is 173:
27.
7. A method for preparing a heterogeneous fiber composite material, comprising: The solution containing Cu and Co ions is converted into a solution containing copper hydroxide, cobalt hydroxide, basic copper carbonate, and basic cobalt carbonate. The carbon fiber felt is immersed in the solution containing copper hydroxide, cobalt hydroxide, basic copper carbonate and basic cobalt carbonate to obtain the precursor; The precursor was annealed in air at at least 400°C to obtain Cu-Co bimetallic oxide modified graphitized carbon fibers. The fragments of graphitized carbon fibers modified with Cu-Co bimetallic oxide were mixed with paraffin fragments and ground to obtain a Cu-Co bimetallic oxide modified graphitized carbon fiber-paraffin composite material.
8. The preparation method according to claim 7, characterized in that, The mass ratio of the Cu-Co bimetallic oxide-modified graphitized carbon fiber to paraffin wax is 3:
7.
9. The preparation method according to claim 7, characterized in that, The molar ratio of Cu ions to Co ions is 1:
2.
10. The preparation method according to claim 7, characterized in that, The carbon fiber felt is immersed in the solution containing copper hydroxide, cobalt hydroxide, basic copper carbonate and basic cobalt carbonate for 30 minutes.