A method for preparing a nitrogen / sulfur co-doped carbon film with low infrared emissivity
By performing nitrogen/sulfur co-doping on the carbon film, a carbon film with abundant defects is formed, which solves the problem of high infrared radiation intensity of carbon materials on the surface of aircraft and achieves infrared stealth effect with low infrared emissivity and fast temperature response.
Patent Information
- Application Number
- CN202311766571.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-20
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2043-12-20
AI Technical Summary
Existing carbon materials tend to generate a large amount of infrared radiation on the surface of aircraft, making it difficult to effectively reduce the intensity of infrared radiation and affecting the stealth effect.
By activating the carbon film in a potassium hydroxide solution and then calcining it in an atmosphere containing thioacetamide, a nitrogen/sulfur co-doped carbon film is formed. The heteroatoms are used to create a large number of defects to enhance conductivity and reduce infrared emissivity.
The prepared nitrogen/sulfur co-doped carbon film has an infrared emissivity as low as 0.349 in the 3-5 μm band, exhibits good Joule thermal properties, achieves rapid temperature response, and achieves infrared stealth effect.
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Figure CN117819547B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a preparation method of a nitrogen / sulfur co-doped carbon film with low infrared emissivity. BACKGROUND
[0002] In recent years, various aircrafts are continuously developed, however, the surface temperature of the aircrafts is increased during operation, thereby generating a large amount of infrared radiation, which is easily captured by high-sensitivity infrared detection equipment. In view of this, the infrared stealth technology represented by low infrared emissivity materials can obviously reduce the infrared radiation intensity of the surface of the device and has been widely concerned. Among them, carbon materials have become a research hotspot in the field of infrared stealth materials due to their high electrical conductivity, excellent mechanical properties and environmental resistance. SUMMARY
[0003] The application aims to provide a preparation method of a nitrogen / sulfur co-doped carbon film with low infrared emissivity.
[0004] The preparation method of the nitrogen / sulfur co-doped carbon film comprises the following steps:
[0005] (1) immersing a carbon film into a potassium hydroxide solution, drying to obtain an activated carbon film;
[0006] (2) calcining the activated carbon film in an atmosphere containing thioacetamide to obtain a nitrogen / sulfur co-doped carbon film.
[0007] In step (1), the carbon film is formed by a plurality of carbon nanotubes with a diameter of 60-65 nm being intertwined with each other, and the carbon film has a good conductive network.
[0008] In step (1), the thickness of the nitrogen / sulfur co-doped carbon film is 20-30 mu m.
[0009] In step (1), the concentration of the potassium hydroxide solution is 2-2.5 mol / L; the carbon film is activated by the KOH solution, so that more active sites of the carbon film can be formed in the subsequent heat treatment process, and the doping of heteroatoms is facilitated.
[0010] In step (1), the activation time of the carbon film in the KOH solution is not less than 24 h.
[0011] In step (2), the activated carbon film is calcined in an atmosphere containing thioacetamide, and the addition amount of the thioacetamide is 1.0-4.0 g.
[0012] The carbon film is doped by nitrogen and sulfur atoms, and a nitrogen / sulfur co-doped carbon film with rich defects is obtained.
[0013] In step (2), the calcination temperature is 500-550 DEG C, the heat treatment holding time is 2-2.5 h, and the heating rate is 5-5.5 DEG C / min.
[0014] Beneficial effects: Compared with the prior art, the carbon film prepared by the method has the following remarkable advantages: the infrared emissivity of the carbon film prepared by the method can be as low as 0.349 in the 3-5 mu m wave band; and the carbon film also has good joule heat performance, so that the material can quickly reach the required temperature at low voltage, and the infrared stealth effect on the target device is realized. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 SEM images of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4;
[0016] Figure 2 X-ray diffraction spectra of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4;
[0017] Figure 3 XPS spectra of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4;
[0018] Figure 4 Electrical conductivity data of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4;
[0019] Figure 5 Joule heat performance of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4;
[0020] Figure 6 Infrared emissivity of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4. DETAILED DESCRIPTION
[0021] Example 1
[0022] The preparation method of the nitrogen / sulfur co-doped carbon film comprises the following steps:
[0023] (1) Activation: immerse a 30mm*30mm carbon film in a 2mol / L KOH solution, and stir at room temperature for 24h;
[0024] (2) Dry the immersed carbon film by air drying to obtain an activated carbon film with a thickness of 25 mu m;
[0025] (3) The obtained activated carbon film was placed in a tube furnace for calcination; 1.0 g of thioacetamide was placed upstream of the tube furnace, and the activated carbon film was placed downstream of the tube furnace; the calcination temperature was 500°C, the holding time was 2 h, and the heating rate was 5°C / min, to obtain a nitrogen / sulfur co-doped carbon film-1.
[0026] Example 2
[0027] The preparation method of Example 2 was completely identical to that of Example 1, except that the amount of thioacetamide added in step (3) was 2.0 g, to obtain a nitrogen / sulfur co-doped carbon film-2.
[0028] Example 3
[0029] The preparation method of Example 3 was completely identical to that of Example 1, except that the amount of thioacetamide added in step (3) was 3.0 g, to obtain a nitrogen / sulfur co-doped carbon film-3.
[0030] Example 4
[0031] The preparation method of Example 4 was completely identical to that of Example 1, except that the amount of thioacetamide added in step (3) was 4.0 g, to obtain a nitrogen / sulfur co-doped carbon film-4.
[0032] Figure 1 The SEM images of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4 at the order of 500 nm are shown in Figure 1. Figure 1 It can be seen that the carbon film is formed by many carbon nanotubes with a diameter of about 65 nm intertwined with each other to form a good conductive network.
[0033] Figure 2 The XRD spectra of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4 are shown in Figure 2. Figure 2 It can be seen that the characteristic peak (002) moves to a lower angle with the increase of the amount of nitrogen and sulfur atoms doped, indicating that the heteroatoms are successfully doped on the carbon film.
[0034] Figure 3 The XPS spectra of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4 are shown in Figure 3. Figure 3 It can be seen that the nitrogen / sulfur co-doped carbon film contains carbon, sulfur, nitrogen, and oxygen elements, indicating that the nitrogen and sulfur elements are successfully doped on the carbon film, and the doping of the two elements effectively improves the defect level of the carbon film, thereby improving the electrical conductivity of the carbon film.
[0035] Figure 4 The electrical conductivity of the nitrogen / sulfur co-doped carbon films prepared in Examples 1-4 is shown in Table 1. Figure 4As can be seen from the figure, the conductivity gradually increases with the increase of the amount of thioacetamide. This is because the nitrogen and sulfur elements gradually increase, and the introduction of nitrogen elements is to provide active sites, so that the substitution of sulfur elements occurs inside the carbon instead of the edge of the carbon, which enhances the defect level of the carbon film, and the introduction of sulfur can effectively improve the conductivity of the carbon film. And with the increase of the content of thioacetamide, the increase amplitude of its conductivity changes from steep increase to gentle rise, and when the mass of thioacetamide placed upstream of the tube furnace is 4.0 g, its conductivity changes little.
[0036] Figure 5 The joule heat performance of the nitrogen / sulfur co-doped carbon film prepared in examples 1-4 was tested, and the results are shown in the following table: Figure 5 As can be seen from the figure, with the increase of the applied voltage, the surface temperature also increases accordingly. In addition, with the increase of the content of thioacetamide, the surface temperature increases in turn, and under the voltage of 2.5V, the highest temperature of the carbon film can reach 95℃ within 200s, indicating that the prepared nitrogen / sulfur co-doped carbon film has good joule heat performance.
[0037] Figure 6 The infrared emissivity of the nitrogen / sulfur co-doped carbon film prepared in examples 1-4 was tested, and the results are shown in the following table: Figure 6 As can be seen from the figure, the product prepared has a lower infrared emissivity (<0.5) in the 3-5μm wave band; it is shown that the introduction of nitrogen and sulfur atom co-doping can effectively improve the conductivity of the carbon film, thereby reducing its infrared emissivity; with the increase of the mass of thioacetamide placed upstream of the tube furnace, the infrared emissivity continuously decreases, and the lowest infrared emissivity can reach 0.349. When the doping amount reaches a certain degree, continuing to increase the content of thioacetamide will not reduce the infrared emissivity, because the continuous increase of the introduction amount will reach the saturation of the doping amount.
Claims
1. A method for producing a nitrogen / sulfur co-doped carbon film having a low infrared emissivity, characterized by, The method comprises the following steps: (1) immersing a carbon film into a potassium hydroxide solution, and drying to obtain an activated carbon film; the carbon film is formed by a plurality of carbon nanotubes with a diameter of 60-65 nm being intertwined with each other; (2) calcining the activated carbon film in an atmosphere containing thioacetamide to obtain a nitrogen / sulfur co-doped carbon film.
2. The method of claim 1, wherein the method further comprises: In step (1), the thickness of the nitrogen / sulfur co-doped carbon film is 20-30 μm.
3. The method of claim 1, wherein the method further comprises: In step (1), the concentration of the potassium hydroxide solution is 2-2.5 mol / L.
4. The method of claim 1, wherein the method further comprises: In step (1), the activation time of the carbon film in the KOH solution is not less than 24 h.
5. The method of claim 1, wherein the method further comprises: In step (2), the activated carbon film is calcined in an atmosphere containing thioacetamide, and the addition amount of thioacetamide is 1.0-4.0 g.
6. The method of claim 1, wherein the method further comprises: In step (2), the calcination temperature is 500-550 ℃, the holding time is 2-2.5 h, and the heating rate is 5-5.5 ℃ / min.