In-situ oriented carbon nanotube / silicon nitride nanoribbon composite material and preparation method thereof

Abstract

The application provides an in-situ oriented carbon nanotube / silicon nitride nanobelt composite material and a preparation method thereof, and comprises the following steps: uniformly mixing methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water and nitric acid according to a certain proportion, and obtaining a siloxane xerogel precursor after stirring and drying; obtaining a silicon nitride nanomaterial by a carbothermal reduction reaction method under high-temperature conditions; injecting a mixed solution of ethanol, ethylenediamine and ferrocene into a tube furnace by a floating CVD method under high-temperature conditions, and growing carbon nanotubes on the surface of the silicon nitride nanobelt to obtain the in-situ oriented carbon nanotube / silicon nitride nanobelt composite material; and the application grows the carbon nanotubes on the surface of the silicon nitride nanobelt material by the floating CVD method to improve the electromagnetic shielding performance of the silicon nitride nanocomposite material, and finally, the carbon nanotube / silicon nitride nanobelt composite material with light weight, flexibility and good electromagnetic shielding performance is prepared.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation, and specifically relates to an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material and its preparation method. Background Technology

[0002] While modern advanced electronic and communication systems offer convenience and advancements, they also bring severe electromagnetic interference. This interference not only damages the performance of our everyday equipment but also has serious adverse effects on our health, safety, and living environment. Currently, mitigating the hazards of electromagnetic interference through highly efficient shielding materials is crucial for controlling and minimizing its harmful impacts on human health.

[0003] Silicon nitride nanoribbons are a widely used nanomaterial with excellent properties such as high strength, high hardness, thermal shock resistance, corrosion resistance, low dielectric constant, and low dielectric loss, making them an ideal substrate for electromagnetic shielding materials. Furthermore, their lightweight and flexible properties make them a preferred material for flexible wearable devices. However, because silicon nitride nanoribbons are ceramic nanomaterials, they exhibit electrical insulation properties, resulting in poor electromagnetic shielding effects and limiting their further application in flexible wearable devices.

[0004] Currently, carbon nanotubes are mainly grown on silicon nitride surfaces using physical methods or solvothermal methods to achieve electromagnetic shielding. For example, carbon nanotube / silicon nitride nanocomposites can be prepared using a solvothermal method by modifying the surface of nano-silicon nitride and acidifying the surface of carbon nanotubes, or by directly combining carbon nanotubes with silicon nitride ceramic materials through physical-mechanical methods. Both methods can produce bulk and powder composite materials with good performance. However, these two preparation methods result in relatively weak interfacial bonding between carbon nanotubes and silicon nitride nanoribbons, making them prone to detachment. Furthermore, their application in flexible wearables is still limited by their macroscopic morphology, preventing the full utilization of their excellent properties in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material and its preparation method, which solves the problem of relatively weak interfacial bonding between carbon nanotubes and silicon nitride nanoribbons and their easy detachment.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material and its preparation method, comprising the following steps:

[0008] Step 1: Mix methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water and nitric acid, then stir and dry to obtain a siloxane dry gel precursor;

[0009] Step 2: The siloxane dry gel precursor is grown by carbothermal reduction reaction to obtain silicon nitride nanoribbon thin film.

[0010] Step 3: A mixed solution of ethanol, ethylenediamine and ferrocene is injected onto a silicon nitride nanoribbon film by floating CVD method, and carbon nanotubes are grown on the surface of the silicon nitride nanoribbon film to obtain an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material.

[0011] Preferably, in step 1, the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid is 1:1:8:2:1 to 10:1:8:2:1.

[0012] Preferably, in step 1, the stirring speed is 100-600 r / min and the stirring time is 10-120 min.

[0013] Preferably, in step 1, the drying temperature is 40–200°C and the drying time is 1–24 hours.

[0014] Preferably, in step 2, the macroscopic body of the silicon nitride nanoribbon material grown is one or more of a bulk, powder, or film.

[0015] Preferably, in step 3, the mass ratio of ethylenediamine to ferrocene in the mixed solution of ethanol, ethylenediamine, and ferrocene is 5:1 to 20:1.

[0016] Preferably, in step 3, the growth temperature of carbon nanotubes is 700–900℃, and the growth time is 10–60 min.

[0017] Preferably, in step 3, the carbon nanotubes are one or a mixture of several types of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0018] An in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material is prepared using the aforementioned preparation method.

[0019] Preferably, the composite material has a total shielding effectiveness of 55dB or more in the X-band.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This invention is the first to employ in-situ oriented carbon nanotubes grown on the surface of silicon nitride nanoribbons. Through the face-to-face interface between the carbon nanotubes and the silicon nitride nanoribbons, a stronger interfacial bonding force is achieved, resulting in a tighter bond between the carbon nanotubes and the silicon nitride nanoribbons, making them less prone to detachment. Compared to traditional physical or solvothermal methods for growing carbon nanotubes on silicon nitride surfaces, this method achieves a more robust and tougher effect, enhancing the composite material's electromagnetic shielding performance while simultaneously improving its lightweight and flexibility. Specifically:

[0022] (1) Lightweight, much lighter than traditional fiber fabrics;

[0023] (2) Flexibility: Compared with one-dimensional linear and two-dimensional sheet aggregates, two-dimensional nanoribbons are more flexible and have stronger deformation ability.

[0024] (3) The structure is stable. Compared with physical mixing, the interface between in-situ grown carbon nanotubes and silicon nitride nanoribbons is stronger and they are not easy to fall off during mechanical deformation. They are more suitable for preparing flexible wearable materials.

[0025] (4) Electromagnetic interference resistance: The electromagnetic shielding performance of silicon nitride nanomaterials is further enhanced by the growth of in-situ oriented carbon nanotubes.

[0026] To improve the electrical insulation and electromagnetic shielding effect of silicon nitride nanomaterials and enable their application in flexible wearables, this invention proposes in-situ oriented growth of carbon nanotubes on the surface of silicon nitride nanoribbons. Compared with existing physical or solvothermal methods, the floating CVD method results in a stronger interfacial bond between silicon nitride nanoribbons and carbon nanotubes, giving them superior electrical conductivity while maintaining their lightweight and flexible properties, thus making them better suited for flexible wearables. Attached Figure Description

[0027] Figure 1 This is a macroscopic optical photograph showing the flexible silicon nitride nanoribbon thin film prepared in Example 1 of this invention;

[0028] Figure 2 This is a lightweight macroscopic optical photograph of the silicon nitride nanoribbon thin film prepared in Example 1 of this invention;

[0029] Figure 3 These are optical photographs of the macroscopic morphology of the carbon nanotube / silicon nitride nanoribbon thin film prepared in Example 4 of this invention.

[0030] Figure 4 This is a SEM image of the silicon nitride nanoribbon film prepared in Example 2 of this invention;

[0031] Figure 5 This is a SEM image of the carbon nanotube / silicon nitride nanoribbon film prepared in Example 4 of this invention;

[0032] Figure 6 These are the XRD patterns of the silicon nitride nanoribbon thin film and the carbon nanotube / silicon nitride nanoribbon thin film prepared by this invention;

[0033] Figure 7 This is a comparison diagram of the electromagnetic shielding performance of the silicon nitride nanoribbon film prepared in this invention and the carbon nanotube / silicon nitride nanoribbon film. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments.

[0035] Compared to the methods of preparing carbon nanotube / silicon nitride nanocomposites by modifying the surface of nano-silicon nitride and acidifying the surface of carbon nanotubes, and by directly combining carbon nanotubes with silicon nitride materials through physical and mechanical methods, this invention enables a stronger interfacial bond between silicon nitride nanoribbons and carbon nanotubes. This allows the superior properties of both materials to be maximized, and it shows greater potential and advantages in achieving lightweight, flexible, and electromagnetic shielding properties in carbon nanotube / silicon nitride nanoribbon composites, making it better suited for the field of flexible wearables.

[0036] This invention proposes a multifunctional integrated carbon nanotube / silicon nitride nanoribbon composite material with lightweight, flexible and excellent electromagnetic shielding performance. Specifically, a material composed of grown silicon nitride nanoribbons is used as a three-dimensional framework, and then carbon nanotubes are grown on the surface of silicon nitride nanoribbons by injection floating CVD method to obtain a multifunctional integrated macroscopic carbon nanotube / silicon nitride nanoribbon composite material with lightweight, high strength and toughness and excellent electromagnetic shielding performance.

[0037] The composite material described above has a total shielding effectiveness of over 55 dB in the X-band (8–12 GHz).

[0038] The present invention provides a method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material, comprising the following steps:

[0039] Step 1: Weigh methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid according to the corresponding mass ratio, pour them into a beaker and mix evenly. After stirring and drying, a siloxane dry gel precursor is obtained.

[0040] Using an electronic weighing instrument, a certain proportion of reagents such as methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid were weighed into a beaker. The weighed mixed solution was stirred to obtain a siloxane sol, which was then placed in an oven for drying to finally obtain a siloxane dry gel precursor.

[0041] Step 2: Silicon nitride nanoribbon materials are grown at high temperature using a carbothermal reduction reaction method.

[0042] Weigh 0.1 to 10 g of the siloxane dry gel precursor prepared in step 1 and put it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper flat on the top of the graphite jar.

[0043] The graphite jar was placed in a tube furnace with the open end facing the gas inlet. Nitrogen gas was introduced and heated to 1500°C at a rate of 5°C / min and held for several hours to obtain silicon nitride nanoribbon materials.

[0044] The macroscopic body of the silicon nitride nanoribbon material grown is one or more of the following: bulk, powder, or thin film.

[0045] Step 3: The silicon nitride nanoribbon material obtained in Step 2 is placed in a tube furnace. Under high temperature conditions, a mixed solution of ethanol, ethylenediamine, and ferrocene is injected into the tube furnace using a floating CVD method. Carbon nanotubes are grown on the surface of the silicon nitride nanoribbon material to obtain an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material. Specifically:

[0046] The silicon nitride nanoribbon film prepared in step 2 is fixed on a graphite plate by a molybdenum wire, then placed in a tube furnace, a protective gas is introduced and the temperature is raised.

[0047] When the furnace reaches the designated temperature, a pre-prepared mixed solution of ethanol, ethylenediamine, and ferrocene is injected into the tube furnace using a syringe. After injection, the needle is removed, the pores are sealed with vacuum mud, and the tube furnace is cooled to room temperature.

[0048] Specifically:

[0049] In step 1, the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid is 1:1:8:2:1 to 10:1:8:2:1. The stirring speed is 100 to 600 r / min, the stirring time is 10 to 120 min, the drying temperature is 40 to 200℃, and the drying time is 1 to 24 h.

[0050] In step 2, the flow rate of nitrogen gas is 50-500 mL / min, and the holding time is 0.5-5 h.

[0051] In step 3, the mass ratio of ethylenediamine to ferrocene in the mixed solution of ethanol, ethylenediamine, and ferrocene is 5:1 to 20:1, the carbon nanotube growth temperature is 700 to 900℃, and the growth time is 10 to 60 min.

[0052] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings.

[0053] Example 1:

[0054] Using an electronic weighing instrument, a fixed amount of reagents was weighed into a beaker according to the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid of 1:1:8:2:1. Then, a magnetic rotor was placed in the beaker, and the speed of the magnetic stirrer was adjusted to 600 r / min. The beaker was placed on the stirrer and stirred evenly for 10 min. After stirring, the magnetic rotor was removed. The beaker containing the uniformly mixed sol was placed in an oven, and the temperature of the oven was adjusted to 200℃. After drying for 1 h, the beaker was removed from the oven to obtain the siloxane dry gel precursor.

[0055] Weigh 2.5g of siloxane dry gel precursor and place it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper on the top of the jar. Then place the jar horizontally into a tube furnace with the open end facing the gas inlet. Turn on the gas source switch and introduce nitrogen at a flow rate of 450mL / min. Set the program in the tube furnace to heat to 1500℃ at a rate of 10℃ / min and hold for 2 hours. Then lower the furnace temperature to room temperature to obtain silicon nitride nanoribbon thin films.

[0056] The above steps enable the growth of silicon nitride nanoribbon thin films.

[0057] Test results show that the silicon nitride nanoribbon film prepared by growing for 2 hours is lightweight and flexible, and the total shielding effectiveness in the X-band (8-12 GHz) is about 12 dB.

[0058] Example 2:

[0059] Using an electronic weighing instrument, a fixed amount of reagents was weighed into a beaker according to the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid of 5:1:8:2:1. Then, a magnetic rotor was placed in the beaker, and the speed of the magnetic stirrer was adjusted to 350 r / min. The beaker was placed on the stirrer and stirred evenly for 65 min. After stirring, the magnetic rotor was removed. The beaker containing the uniformly mixed sol was placed in an oven, and the temperature of the oven was adjusted to 120℃. After drying for 12 h, the beaker was removed from the oven to obtain the siloxane dry gel precursor.

[0060] Weigh 2.5g of siloxane dry gel precursor and place it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper on the top of the jar. Then place the jar horizontally into a tube furnace with the open end facing the gas inlet. Turn on the gas source switch and introduce nitrogen at a flow rate of 450mL / min. Set the program in the tube furnace to heat to 1500℃ at a rate of 10℃ / min and hold for 2 hours. Then lower the furnace temperature to room temperature to obtain silicon nitride nanoribbon thin films.

[0061] The above steps enable the growth of silicon nitride nanoribbon thin films.

[0062] Test results show that the silicon nitride nanoribbon film prepared by growing for 2 hours is lightweight and flexible, and the total shielding effectiveness in the X-band (8-12 GHz) is about 15 dB.

[0063] Example 3:

[0064] Using an electronic weighing instrument, a measured amount of reagents was weighed into a beaker according to the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid of 10:1:8:2:1. Then, a magnetic rotor was placed in the beaker, and the speed of the magnetic stirrer was adjusted to 100 r / min. The beaker was placed on the stirrer and stirred evenly for 120 min. After stirring, the magnetic rotor was removed. The beaker containing the uniformly mixed sol was placed in an oven, and the temperature of the oven was adjusted to 40℃. After drying for 24 h, the beaker was removed from the oven to obtain the siloxane dry gel precursor.

[0065] Weigh 2.5g of siloxane dry gel precursor and place it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper on the top of the jar. Then place the jar horizontally into a tube furnace with the open end facing the gas inlet. Turn on the gas source switch and introduce nitrogen at a flow rate of 450mL / min. Set the program in the tube furnace to heat to 1500℃ at a rate of 10℃ / min and hold for 4 hours. Then lower the furnace temperature to room temperature to obtain silicon nitride nanoribbon thin films.

[0066] Test results show that the silicon nitride nanoribbon film prepared by growing for 4 hours is lightweight and flexible, and its total shielding effectiveness in the X-band (8-12 GHz) is about 20 dB.

[0067] Example 4:

[0068] Using an electronic weighing instrument, a fixed amount of reagents was weighed into a beaker according to the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid of 5:1:8:2:1. Then, a magnetic rotor was placed in the beaker, and the speed of the magnetic stirrer was adjusted to 350 r / min. The beaker was placed on the stirrer and stirred evenly for 65 min. After stirring, the magnetic rotor was removed. The beaker containing the uniformly mixed sol was placed in an oven, and the temperature of the oven was adjusted to 120℃. After drying for 12 h, the beaker was removed from the oven to obtain the siloxane dry gel precursor.

[0069] Weigh 2.5g of siloxane dry gel precursor and place it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper on the top of the jar. Then place the jar horizontally into a tube furnace with the open end facing the gas inlet. Turn on the gas source switch and introduce nitrogen at a flow rate of 450mL / min. Set the program in the tube furnace to heat to 1500℃ at a rate of 10℃ / min and hold for 2 hours. Then lower the furnace temperature to room temperature to obtain silicon nitride nanoribbon thin films.

[0070] The prepared silicon nitride nanoribbon film was fixed onto a high-temperature resistant substrate using molybdenum wire, and then placed in a tube furnace. Argon gas was first introduced at a rate of 500 mL / min, and the furnace temperature was raised to 700 °C at a rate of 15 °C / min. When the temperature reached 700 °C, a pre-prepared mixed solution of ethanol, ethylenediamine, and ferrocene was injected into the tube furnace through a syringe needle at an injection rate of 20 mL / h for 60 min. After the injection was completed, the needle was removed, the pores were sealed with vacuum mud, and the temperature inside the tube furnace was lowered to room temperature to obtain the in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material.

[0071] Test results show that the prepared carbon nanotube / silicon nitride nanoribbon composite material is lightweight and flexible, and its total shielding effectiveness in the X-band (8-12GHz) can reach about 40dB.

[0072] Example 5:

[0073] Using an electronic weighing instrument, a fixed amount of reagents was weighed into a beaker according to the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid of 5:1:8:2:1. Then, a magnetic rotor was placed in the beaker, and the speed of the magnetic stirrer was adjusted to 350 r / min. The beaker was placed on the stirrer and stirred evenly for 65 min. After stirring, the magnetic rotor was removed. The beaker containing the uniformly mixed sol was placed in an oven, and the temperature of the oven was adjusted to 120℃. After drying for 12 h, the beaker was removed from the oven to obtain the siloxane dry gel precursor.

[0074] Weigh 2.5g of siloxane dry gel precursor and place it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper on the top of the jar. Then place the jar horizontally into a tube furnace with the open end facing the gas inlet. Turn on the gas source switch and introduce nitrogen at a flow rate of 450mL / min. Set the program in the tube furnace to heat to 1500℃ at a rate of 10℃ / min and hold for 2 hours. Then lower the furnace temperature to room temperature to obtain silicon nitride nanoribbon thin films.

[0075] The prepared silicon nitride nanoribbon film was fixed onto a high-temperature resistant substrate using molybdenum wire, and then placed in a tube furnace. Argon gas was first introduced at a rate of 500 mL / min, and the furnace temperature was raised to 850 °C at a rate of 15 °C / min. When the temperature reached 850 °C, a pre-prepared mixed solution of ethanol, ethylenediamine, and ferrocene was injected into the tube furnace through a syringe needle at an injection rate of 20 mL / h for 30 min. After the injection was completed, the needle was removed, the pores were sealed with vacuum mud, and the temperature inside the tube furnace was lowered to room temperature to obtain the in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material.

[0076] Test results show that the prepared carbon nanotube / silicon nitride nanoribbon composite material is lightweight and flexible, and its total shielding effectiveness in the X-band (8-12GHz) can reach about 55dB.

[0077] Example 6:

[0078] Using an electronic weighing instrument, a fixed amount of reagents was weighed into a beaker according to the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid of 5:1:8:2:1. Then, a magnetic rotor was placed in the beaker, and the speed of the magnetic stirrer was adjusted to 350 r / min. The beaker was placed on the stirrer and stirred evenly for 65 min. After stirring, the magnetic rotor was removed. The beaker containing the uniformly mixed sol was placed in an oven, and the temperature of the oven was adjusted to 120℃. After drying for 12 h, the beaker was removed from the oven to obtain the siloxane dry gel precursor.

[0079] Weigh 2.5g of siloxane dry gel precursor and place it into the bottom of a horizontally placed graphite jar with one end open. Place a sheet of graphite paper on the top of the jar. Then place the jar horizontally into a tube furnace with the open end facing the gas inlet. Turn on the gas source switch and introduce nitrogen at a flow rate of 450mL / min. Set the program in the tube furnace to heat to 1500℃ at a rate of 10℃ / min and hold for 2 hours. Then lower the furnace temperature to room temperature to obtain silicon nitride nanoribbon thin films.

[0080] The prepared silicon nitride nanoribbon film was fixed onto a high-temperature resistant substrate using molybdenum wire, and then placed in a tube furnace. Argon gas was first introduced at a rate of 500 mL / min, and the furnace temperature was raised to 900 °C at a rate of 15 °C / min. When the temperature reached 900 °C, a pre-prepared mixed solution of ethanol, ethylenediamine, and ferrocene was injected into the tube furnace through a syringe needle at an injection rate of 20 mL / h for 10 min. After the injection was completed, the needle was removed, the pores were sealed with vacuum mud, and the temperature inside the tube furnace was lowered to room temperature to obtain the in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material.

[0081] Test results show that the prepared carbon nanotube / silicon nitride nanocomposite material is lightweight and flexible, and its total shielding effectiveness in the X-band (8-12GHz) can reach more than 40dB.

Claims

1. A method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material, characterized in that, Includes the following steps: Step 1: Mix methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water and nitric acid, then stir and dry to obtain a siloxane dry gel precursor; Step 2: The siloxane dry gel precursor is grown by carbothermal reduction reaction to obtain silicon nitride nanoribbon thin film. Step 3: A mixed solution of ethanol, ethylenediamine and ferrocene is injected onto a silicon nitride nanoribbon film by floating CVD method, and carbon nanotubes are grown on the surface of the silicon nitride nanoribbon film to obtain an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material. In step 1, the mass ratio of methyltrimethoxysilane, dimethyldimethoxysilane, ethanol, water, and nitric acid is 1:1:8:2:1 to 10:1:8:2:1; In step 3, the mass ratio of ethylenediamine to ferrocene in the mixed solution of ethanol, ethylenediamine, and ferrocene is 5:1 to 20:

1.

2. The method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material according to claim 1, characterized in that, In step 1, the stirring speed is 100-600 r / min and the stirring time is 10-120 min.

3. The method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material according to claim 1, characterized in that, In step 1, the drying temperature is 40–200 °C, and the drying time is 1–24 h.

4. The method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material according to claim 1, characterized in that, In step 2, the macroscopic body of the silicon nitride nanoribbon material grown is one or more of the following: bulk, powder, or thin film.

5. The method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material according to claim 1, characterized in that, In step 3, the growth temperature of carbon nanotubes is 700–900 ℃, and the growth time is 10–60 min.

6. The method for preparing an in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material according to claim 1, characterized in that, In step 3, the carbon nanotubes are one or a mixture of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

7. An in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material, characterized in that, The in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material is prepared by the preparation method according to any one of claims 1-6.

8. The in-situ oriented carbon nanotube / silicon nitride nanoribbon composite material according to claim 7, characterized in that, The composite material achieves a total shielding effectiveness of over 55 dB in the X-band.

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