Wave-absorbing worm-like / hair-like composite beta-SiC nanomaterial and preparation method thereof

Abstract

The application belongs to the technical field of inorganic nano functional materials, and discloses a worm-like / whisker-like composite beta-SiC nano material for wave absorption and a preparation method thereof. Amorphous silicon dioxide and carbon black are used as raw materials, a platinum-rhodium metal mixture is used as a catalyst, and high-temperature reaction is carried out at 2000-2200 DEG C under inert gas protection for 5-20 hours. The process is controllable. By accurately controlling the reaction time and utilizing the evolution of the VSL growth mechanism, the composite beta-SiC nano material with adjustable worm-like and whisker-like proportion can be prepared. The prepared composite nano material has good impedance matching and strong dielectric loss capacity, and has moderate resistivity. In particular, it is especially suitable as a wave absorption material for a wave absorption coating with high requirements for weather resistance and temperature resistance, can realize wide-band, strong-absorption radar stealth effect, and has important application value in the fields of aerospace and high-end electronic equipment electromagnetic compatibility.

Description

Technical Field

[0001] This invention belongs to the field of inorganic nanomaterials technology, specifically relating to a worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption and its preparation method. Background Technology

[0002] With the rapid development of science and technology, while electronic devices have brought great convenience to people's daily lives and production, they have also generated electromagnetic radiation that cannot be ignored, adversely affecting the normal operation of electronic instruments and equipment. The most effective measure to control electromagnetic radiation is electromagnetic shielding, whose main purpose is to prevent the influence of radio frequency electromagnetic waves and control their radiation intensity within a range that is harmless to the human body. Absorbing materials are electromagnetic functional materials with special properties. These materials can effectively absorb incident electromagnetic waves, converting electromagnetic energy into heat energy or other forms of energy for dissipation, or causing electromagnetic waves to interfere with each other, thereby significantly weakening the intensity of electromagnetic waves. The development trend of absorbing materials is "thin, light, wide, strong, and high," meaning thin material thickness, light material weight, wide absorption bandwidth, high absorption efficiency, high temperature resistance, and meeting the requirements of integrated structure and function. Therefore, exploring a new type of composite absorbing material that adapts to development has profound research significance.

[0003] Silicon carbide, as a traditional microwave absorbing material, has advantages such as high temperature resistance, oxidation resistance, and high strength. However, its intrinsic dielectric constant is high, resulting in poor impedance matching, making it difficult to meet the requirements for broadband and efficient absorption when used alone. Nanostructured SiC, especially SiC with one-dimensional morphology (such as nanowires and nanowhiskers), exhibits superior microwave absorption potential due to its unique geometric anisotropy, high specific surface area, and tunable electromagnetic parameters.

[0004] Currently, there are numerous methods for preparing one-dimensional SiC nanomaterials, such as chemical vapor deposition, sol-gel method, and carbothermal reduction method. However, existing technologies can usually only prepare SiC with a single morphology (such as straight nanowires or randomly stacked short rods). Patent document CN102874810A discloses a method for preparing β-SiC nanopowder, using expandable graphite as the carbon source and industrial silicon powder or silica powder as the silicon source, and preparing β-SiC nanopowder by carbothermal reduction method. The nanopowder prepared by this technology is simple to process, without catalysts or protective gases, but the reaction product has low purity, a single morphology and a wide particle size distribution, and is prone to agglomeration, making it difficult to prepare multi-dimensional composite nanomaterials. When constructing coatings, materials with a single morphology have a limited range of adjustable dielectric parameters, and different morphological structures have different emphases in the dissipation mechanism of electromagnetic waves: whisker-like structures are beneficial for multiple scattering and conduction loss, while worm-like irregular curved structures can enhance interfacial polarization and dipole polarization loss. If a SiC nanomaterial with controllable microstructure can be prepared, combining the two loss mechanisms, it is expected to break through the performance bottleneck of single-morphology materials and achieve wider bandwidth and stronger absorption performance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a worm-like / whisker-like composite β-SiC nanomaterial for radar absorbing and its preparation method. By precisely controlling the process parameters, a composite β-SiC nanomaterial with an optimized ratio of worm-like and whisker-like composite microstructures can be obtained, possessing both excellent impedance matching characteristics and multiple electromagnetic loss mechanisms. This solves the problem that it is difficult to synergistically optimize the impedance matching and loss capabilities of single-morphology SiC radar absorbing materials. It is suitable for preparing high-performance radar absorbing coatings with excellent radar absorption performance.

[0006] To achieve the above objectives, the technical solution adopted in this invention is as follows: a worm-like / whisker-like composite β-SiC nanomaterial for absorbing microwaves, the raw materials of which include amorphous silica and carbon black, with a mass ratio of amorphous silica to carbon black of 1:3; and an added catalyst accounting for 1 to 3% of the total weight of the raw materials.

[0007] Furthermore, the amorphous silica is nanoscale with a particle size ≤100nm and a purity of 99.99%; the carbon black is nanoscale with a particle size ≤80nm and a purity of 99.99%.

[0008] Furthermore, the catalyst is a platinum-rhodium metal mixture with a submicron particle size of 100–500 nm.

[0009] Furthermore, the mass ratio of platinum to rhodium in the platinum-rhodium metal mixture is 3:7 to 7:3.

[0010] The preparation method of this microwave absorbing worm-like / whisker-like composite β-SiC nanomaterial includes the following steps:

[0011] Step 1: Raw material preparation:

[0012] Calculate and weigh the required amorphous silica, carbon black and catalyst according to the mass ratio, and set aside for later use;

[0013] Step 2: Preparation of composite powder:

[0014] The amorphous silica and carbon black weighed in step one are placed in a mixer and mixed thoroughly to obtain composite powder.

[0015] Step 3: Catalyst addition:

[0016] A catalyst is added to the composite powder and mixed until homogeneous to obtain the final reaction precursor.

[0017] Step 4: High-temperature sintering:

[0018] The reaction precursor is placed in the crucible of the high-temperature reaction apparatus, and an inert protective gas is introduced into the reaction chamber and maintained inert protective atmosphere until the reaction is completed. The temperature is increased to 2000-2200℃ at a heating rate of 10-20℃ / min and held at this temperature for 5-20 hours.

[0019] Step 5, Post-processing:

[0020] After the reaction was completed, the product was naturally cooled to room temperature under an inert atmosphere. The product was then removed, crushed, sieved, and impurity removed to obtain worm-like / whisker-like composite β-SiC nanomaterials.

[0021] To balance impedance matching and loss performance, the mass ratio of filamentous structure to worm-like structure in the worm-like / whisker-like composite β-SiC nanomaterial is preferably 50-60%:40-50%; the preferred reaction time range corresponding to this ratio is 12-16 hours.

[0022] Furthermore, the mixing machine rotates at a speed of 80–120 r / min, and the mixing time is 4–6 h.

[0023] Furthermore, the high-temperature reaction device is a graphite furnace or an induction furnace.

[0024] Furthermore, the inert protective gas is argon with a purity of not less than 99.99% and a flow rate of 50-100 mL / min.

[0025] The "worm-like" morphology described in this invention refers to β-SiC nanostructures with irregular, curved, nodular, or short rod-like morphologies and a low aspect ratio; the "whisker-like" morphology refers to β-SiC nanowires / whiskers with a high aspect ratio, relatively smooth surfaces, and straight or slightly curved shapes. The whisker-like β-SiC morphology constructs a conductive network, which is beneficial for conduction loss and multiple reflection / scattering; the worm-like β-SiC morphology introduces a large number of interfaces, defects, and dipoles, enhancing interfacial polarization and dipole polarization losses. The combination of these two morphologies achieves complementarity and synergy in the loss mechanisms, enabling the material to exhibit high absorption efficiency over a wide frequency band.

[0026] This invention is based on the principle of carbothermic reduction reaction. Its reaction mechanism lies in the evolution of a gas-liquid-solid (VSL) growth mechanism: First, under high temperature and argon protection, nanoscale amorphous high-purity SiO2 and nanoscale carbon black undergo a carbothermic reduction reaction to generate gaseous SiO and CO. Pt and Rh metal ultrafine powders form eutectic droplets (liquid phase) with the Si and C components. The SiO and CO in the gas phase are adsorbed, decomposed, and dissolved on the droplet surface. When the Si and C in the droplet reach supersaturation, β-SiC crystals precipitate from the solid-liquid interface between the droplet and the substrate (or the already formed SiC) (solid phase). After nucleation, the growth rate of the β-SiC crystal varies in different directions, resulting in a chaotic growth direction. In the early stages of the reaction or when the reaction time is short, the gas phase supply is relatively intense, leading to a high nucleation density. Simultaneously, the short growth time limits the full extension of the crystal along a single direction. Furthermore, localized airflow disturbances, temperature field inhomogeneities, or defect-induced growth during the reaction process lead to frequent changes in the crystal growth direction. The migration or merging of catalyst droplets can also cause growth interruption followed by regeneration. The grains connect and twist to form nodular morphologies, resulting in discontinuous, curved, nodular, worm-like β-SiC morphologies. With a longer reaction time and a continuous gas supply, the growth rate along the crystal axis is much higher than in other directions. Simultaneously, the liquid alloy particles gradually move towards the whisker tips as the crystal grows, continuously providing Si and C atoms for crystal growth. The crystal grows axially continuously, eventually forming a slender whisker-like β-SiC morphology.

[0027] In step four, the high-temperature sintering stage, sintering temperature and holding time are crucial for controlling the morphology of β-SiC. Too low a temperature results in a slow reaction rate, poor product crystallinity, and an excessively high proportion of worm-like β-SiC. Too high a temperature leads to coarse grains, excessively long whisker-like β-SiC, and increased material brittleness. Therefore, 2000-2200℃ is the optimal temperature for the reduction reaction of SiO2 and carbon black to generate β-SiC. Shorter reaction times result in less directional crystal growth, and the limited fluidity and mediating effect of liquid Pt-Rh alloy particles prevent stable directional growth after gaseous SiO and C dissolve on the alloy particle surface, leading to a higher proportion of worm-like β-SiC. Longer reaction times result in more complete directional growth mediated by liquid alloy particles and a higher proportion of whisker-like β-SiC. The inert gas protection isolates the raw materials and products from air, prevents oxidation, inhibits side reactions, and improves product purity.

[0028] This invention achieves precise control over the ratio of "worm-like" and "whisker-like" morphologies in β-SiC. Firstly, the ratio of catalysts is adjusted. Pt and Rh have slightly different solubilities and eutectic points for Si and C. Based on the material's performance requirements, the surface tension and wettability of the droplets are fine-tuned by adjusting the ratio of the two metals, thus achieving precise control over the ratio of "worm-like" or "whisker-like" morphologies. Using Pt / Rh composite metal ultrafine powder as a catalyst not only effectively reduces the activation energy of the carbothermic reduction reaction, accelerates the reaction process, and shortens the reaction cycle, but also promotes the regular growth of β-SiC crystals, improving the crystallinity and purity of the product. Secondly, the sintering temperature, heating rate, and holding time are controlled. Increasing the proportion of platinum catalyst, decreasing the heating and heating rates, and increasing the holding time result in more whisker-like structures; conversely, decreasing these rates results in more worm-like structures. The whisker-like structures act as "conductive pathways," with a large aspect ratio, which is beneficial for forming an electromagnetic induction network in the matrix, mainly contributing to conductivity losses. The worm-like structure has a rough surface and many defects (multiple grain boundaries), introducing a large number of interfaces, defects, and dipoles, which leads to more interfacial polarization and multiple scattering, enhancing interfacial polarization and dipole polarization losses. The worm-like / whisker-like composite β-SiC nanomaterial structure achieves complementary and synergistic loss mechanisms, enabling the material to have high absorption efficiency over a wide frequency band.

[0029] The worm-like / whisker-like composite β-SiC nanomaterials prepared by this invention have a resistivity of 0.5–159 Ω·cm. In the frequency range of 2–18 GHz, the real part ε′ of its complex permittivity is 6–15, which characterizes the energy storage capacity, and the imaginary part ε″ is 2–8, which characterizes the energy dissipation capacity.

[0030] This invention utilizes nanoscale raw materials. Due to its excellent electrical conductivity, carbon black, when combined with nanoscale amorphous silica, increases the dielectric loss of the composite material. This multiphase composite approach enhances its microwave absorption performance. The resulting nanoscale ceramic microwave absorbing material exhibits superior absorption capabilities compared to non-nanoscale materials, primarily due to the following reasons: 1. Microwave frequencies range from 300MHz to 300GHz, with wavelengths from 1mm to 1m, while nanomaterials range in size from 1 to 100nm, much smaller than microwave wavelengths. Therefore, microwave transmittance is significantly increased, allowing it to penetrate the material more easily. 2. Nanomaterials are small in size, have a large specific surface area, a high proportion of surface atoms to total atoms, and high surface atomic activity, resulting in more pronounced interfacial polarization and multiple scattering phenomena. 3. Due to the quantum size effect, nanomaterials undergo electron energy level splitting. The split energy levels are similar to microwave energies, making them more effective at absorbing electromagnetic waves. 4. Under the influence of electromagnetic waves, the movement of active atoms or electrons on the surface of nanomaterials intensifies, converting electromagnetic energy into heat energy and enhancing the attenuation of electromagnetic waves.

[0031] The beneficial effects of this invention are as follows: This invention uses amorphous silica and carbon black as raw materials, and reacts them at high temperature under specific catalysts and argon protection. The process path is clear, the conditions are controllable, and the product has high purity and good stability. By adjusting the core parameters, the ratio of worm-like and whisker-like β-SiC in the product can be precisely controlled, thereby customizing the complex dielectric parameters of the material and optimizing its impedance matching and electromagnetic wave loss capability. The worm-like / whisker-like composite β-SiC nanomaterial achieves complementarity and synergy in the loss mechanism, enabling the material to have high absorption efficiency over a wide frequency band. The prepared composite nanomaterial is particularly suitable as a radar absorbing material for radar stealth coatings with high requirements for weather resistance and temperature resistance, and has important application value in the fields of aerospace and electromagnetic compatibility of high-end electronic equipment. Attached Figure Description

[0032] Figure 1 A scanning electron microscope image of the composite β-SiC nanomaterial prepared in Example 1 of this invention;

[0033] Figure 2 The graph shows the variation of the complex dielectric constant of the composite β-SiC nanomaterial prepared in Example 1 of the present invention in the frequency range of 2-18 GHz.

[0034] Figure 3 A scanning electron microscope image of the composite β-SiC nanomaterial prepared in Example 2 of this invention;

[0035] Figure 4 This is a graph showing the variation of the complex dielectric constant of the composite β-SiC nanomaterial prepared in Example 2 of the present invention in the frequency range of 2-18 GHz;

[0036] Figure 5This is a scanning electron microscope image of the composite β-SiC nanomaterial prepared in Example 3 of the present invention;

[0037] Figure 6 The curve showing the variation of the complex dielectric constant of the composite β-SiC nanomaterial prepared in Example 3 of this invention in the frequency range of 2-18 GHz;

[0038] Figure 7 The graph shows the reflectance of composite β-SiC nanomaterials of different thicknesses prepared in Example 2 as a function of frequency. Detailed Implementation

[0039] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0040] Example 1:

[0041] A method for preparing worm-like / whisker-like composite β-SiC nanomaterials for microwave absorption includes the following steps:

[0042] Step 1: Raw material preparation:

[0043] Weigh out 10 parts by weight of amorphous silica powder and 30 parts by weight of nano carbon black, and 2% by weight of platinum-rhodium metal mixture, wherein the mass ratio of platinum to rhodium is 6:4, and set aside.

[0044] Step 2: Preparation of composite powder:

[0045] Place the amorphous silica and carbon black weighed in step one into a mixer, and ball mill them at 100 r / min for 6 hours to mix them thoroughly and evenly, thus obtaining a composite powder.

[0046] Step 3: Catalyst addition:

[0047] Add 0.4g of platinum-rhodium metal ultrafine powder to the composite powder and continue mixing until homogeneous to obtain the final reaction precursor.

[0048] Step 4: Sintering and densification:

[0049] The reaction precursor was placed in a graphite crucible and then placed in a high-temperature induction furnace. After sealing, argon gas was introduced into the reaction chamber at a flow rate of 5 L / min to replace the air for 30 minutes. Subsequently, under argon protection, the gas flow rate was maintained at 80 mL / min, and the temperature was increased to 2200℃ at a rate of 15℃ / min. The temperature was then maintained at this temperature for 15 hours.

[0050] Step 5, Post-processing:

[0051] After the reaction was completed, the product was naturally cooled to room temperature under an argon atmosphere. The product was then removed, crushed, passed through a 400-mesh sieve, and impurity removed to obtain worm-like / whisker-like composite β-SiC nanomaterials.

[0052] Example 2:

[0053] A method for preparing worm-like / whisker-like composite β-SiC nanomaterials for microwave absorption includes the following steps:

[0054] Step 1: Raw material preparation:

[0055] Weigh out 10 parts by weight of amorphous silica powder and 30 parts by weight of nano carbon black, and 1% by weight of platinum-rhodium metal mixture, wherein the mass ratio of platinum to rhodium is 7:3, and set aside.

[0056] Step 2: Preparation of composite powder:

[0057] Place the amorphous silica and carbon black weighed in step one into a mixer, and ball mill them at a speed of 80 r / min for 5 hours to mix them thoroughly and evenly, thus obtaining a composite powder.

[0058] Step 3: Catalyst addition:

[0059] Add 0.8g of platinum-rhodium metal ultrafine powder to the composite powder and continue mixing until homogeneous to obtain the final reaction precursor.

[0060] Step 4: Sintering and densification:

[0061] The reaction precursor was placed in a graphite crucible and then placed in a high-temperature induction furnace. After sealing, argon gas was introduced into the reaction chamber at a flow rate of 5 L / min to replace the air for 30 minutes. Subsequently, under argon protection, the gas flow rate was maintained at 50 mL / min, and the temperature was increased to 2100℃ at a rate of 10℃ / min. The temperature was then maintained at this temperature for 5 hours.

[0062] Step 5, Post-processing:

[0063] After the reaction was completed, the product was naturally cooled to room temperature under an argon atmosphere. The product was then removed, crushed, passed through a 400-mesh sieve, and impurity removed to obtain worm-like / whisker-like composite β-SiC nanomaterials.

[0064] Example 3:

[0065] A method for preparing worm-like / whisker-like composite β-SiC nanomaterials for microwave absorption includes the following steps:

[0066] Step 1: Raw material preparation:

[0067] Weigh out 20 parts by weight of amorphous silica powder and 60 parts by weight of nano carbon black, and 3% by weight of platinum-rhodium metal mixture, wherein the mass ratio of platinum to rhodium is 3:7, and set aside.

[0068] Step 2: Preparation of composite powder:

[0069] Place the amorphous silica and carbon black weighed in step one into a mixer, and ball mill them at a speed of 120 r / min for 4 hours to mix them thoroughly and evenly, thus obtaining a composite powder.

[0070] Step 3: Catalyst addition:

[0071] Add 1.2g of platinum-rhodium metal ultrafine powder to the composite powder and continue mixing until homogeneous to obtain the final reaction precursor.

[0072] Step 4: Sintering and densification:

[0073] The reaction precursor was placed in a graphite crucible and then placed in a high-temperature induction furnace. After sealing, argon gas was introduced into the reaction chamber at a flow rate of 5 L / min to replace the air for 30 minutes. Subsequently, under argon protection, the gas flow rate was maintained at 100 mL / min, and the temperature was increased to 2000℃ at a heating rate of 20℃ / min. The temperature was then maintained at this temperature for 20 hours.

[0074] Step 5, Post-processing:

[0075] After the reaction was completed, the product was naturally cooled to room temperature under an argon atmosphere. The product was then removed, crushed, passed through a 400-mesh sieve, and impurity removed to obtain worm-like / whisker-like composite β-SiC nanomaterials.

[0076] The composite β-SiC nanomaterials obtained in Examples 1-3 were dispersed in a silicone resin binder at a mass fraction of 30 wt%, and appropriate amounts of curing agent and solvent were added and stirred evenly to prepare a microwave absorbing coating. This coating was applied to the surface of an alumina ceramic plate with dimensions of 180 mm × 180 mm, with a coating thickness of 2.3-2.6 mm. After curing, its reflection loss was tested in the 2-18 GHz frequency range using the bow-shaped method. The test results are shown in the table below, exhibiting excellent broadband radar wave absorption performance.

[0077] Main performance indicators of microwave absorbing materials prepared in Examples 1-3

[0078] Depend on Figure 1-6It is evident that this invention, through optimized process design, successfully prepared worm-like / whisker-like composite β-SiC nanomaterials with adjustable morphology ratios. These nanomaterials achieved optimal electromagnetic wave absorption in the 2GHz-18GHz frequency range, with the real part ε′ of the complex permittivity fluctuating primarily within the range of 6-15, and the imaginary part ε″ fluctuating within the range of 2-8. They exhibit excellent broadband absorption performance, with a reflectivity as low as -37dB, demonstrating superior performance as a microwave absorbing filler and promising prospects for industrial applications.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing worm-like / whisker-like composite β-SiC nanomaterials for microwave absorption, characterized in that, Includes the following steps: Step 1: Raw material preparation: Calculate and weigh the required amorphous nano-silica, nano-carbon black and catalyst according to the mass ratio, and set aside; the catalyst is a platinum-rhodium metal mixture with a mass ratio of platinum to rhodium of 3:7 to 7:3 and a particle size of 100 to 500 nm (submicron level); Step 2: Preparation of composite powder: The amorphous silica and carbon black weighed in step one are placed in a mixer and mixed thoroughly to obtain composite powder. Step 3: Catalyst addition: A catalyst was added to the composite powder and the mixture was continued until homogeneous to obtain the final reaction precursor. Step 4: High-temperature sintering: The reaction precursor is placed in the crucible of the high-temperature reaction apparatus, an inert protective gas is introduced into the reaction chamber and the inert protective atmosphere is maintained until the reaction is completed. The temperature is increased to 2000-2200℃ at a heating rate of 10-20℃ / min and held at this temperature for 5-20 hours. Step 5, Post-processing: After the reaction was completed, the product was naturally cooled to room temperature under an inert atmosphere. The product was then removed, crushed, sieved, and impurity removed to obtain worm-like / whisker-like composite β-SiC nanomaterials.

2. The method for preparing a worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption according to claim 1, characterized in that: In step two, the mixing machine rotates at a speed of 80–120 r / min, and the mixing time is 4–6 h.

3. The method for preparing a worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption according to claim 1, characterized in that: The high-temperature reaction device in step four is a graphite furnace or an induction furnace.

4. The method for preparing a worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption according to claim 1, characterized in that: The inert protective gas in step four is argon, with a purity of not less than 99.99% and a flow rate of 50-100 mL / min.

5. The method for preparing a worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption according to claim 1, characterized in that: In the worm-like / whisker-like composite β-SiC nanomaterials, the mass ratio of whisker-like structures to worm-like structures is 50–60%:40–50%; the reaction time ranges from 12 to 16 hours.

6. The method for preparing a worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption according to claim 1, characterized in that: The prepared worm-like / whisker-like composite β-SiC nanomaterials have a resistivity of 0.5–159 Ω·cm and, in the frequency range of 2–18 GHz, a real part ε′ of complex permittivity of 6–15 and an imaginary part ε″ of 2–8.

7. A method for preparing worm-like / whisker-like composite β-SiC nanomaterials for absorbing microwaves as described in claim 1, characterized in that: The raw materials include amorphous silica and carbon black, with a mass ratio of amorphous silica to carbon black of 1:3; an additional catalyst is added, accounting for 1 to 3% of the total weight of the raw materials.

8. The worm-like / whisker-like composite β-SiC nanomaterial for absorbing microwaves prepared by the method described in claim 7, characterized in that: Amorphous silica is nanoscale, with a particle size ≤100nm and a purity of 99.99%.

9. The worm-like / whisker-like composite β-SiC nanomaterial for microwave absorption prepared by the method described in claim 7, characterized in that: The carbon black is nanoscale, with a particle size ≤80nm and a purity of 99.99%.

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