Preparation method of cobalt-based multi-spectrum silicon carbide aerogel

Abstract

The present application relates to a kind of preparation method of cobalt-based multispectral silicon carbide aerogel. First, configure composite precursor suspension, then freeze-drying and heat treatment process are prepared. The unique structure of silicon carbide aerogel makes it play an indispensable role in the field of light weight and high temperature resistance, and the microwave absorption performance of silicon carbide material makes silicon carbide aerogel become the ideal carrier with multispectral compatible protection function. By combining cobalt-based functional filler with silicon carbide aerogel, it is an effective means to realize multispectral compatible protection.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology and relates to a method for preparing a lightweight cobalt-based multispectral silicon carbide aerogel for visible-near-infrared-microwave compatible protection. The entire preparation process includes the preparation of a composite precursor suspension, freeze-drying, and heat treatment of the composite precursor. Background Technology

[0002] Microwave, infrared, and visible light bands play crucial roles in modern technological applications and are among the most commonly used bands. With the continuous development of detection system technology and the increasing accuracy of detection, the demand for multispectral integrated protective materials is becoming increasingly urgent. Traditionally, protective materials are designed and applied for specific bands. However, the complexity and diversity of modern technological applications require more comprehensive solutions. Single-band protective materials can no longer meet the modern demands of multi-band integrated detection. Therefore, the development of multi-band compatible protective materials has become an inevitable trend in the future development of protective materials. Such multi-band compatible protective materials not only need to have excellent protective performance in the microwave, infrared, and visible light bands, but also need to possess good heat resistance, weather resistance, and other properties to meet the needs of different application scenarios. Therefore, future research and development of protective materials will focus more on the integration and optimization of multi-band performance to achieve wider and more efficient applications.

[0003] Researchers have developed multispectral compatible protective materials that meet the functions of different wavelength bands through material design and structural design. Zhu et al. (Nature Communications 2021, 12(1)) designed a ZnS / Ge multilayer selective emitter and a Cu-ITO-Cu absorbing metal surface to achieve compatible protection in the visible, mid-infrared, laser and microwave bands. CN114690278 A discloses a multilayer dielectric film that uses alternating stacks of various dielectric materials with different refractive indices to achieve visible / near-infrared / laser compatible protection. Professor Li Zhigang's team at the National University of Defense Technology (Journal of Vacuum Science and Technology, 2022, 42(06)) designed a multispectral compatible protective film that is compatible with visible, near-infrared and laser bands under a green background by introducing defects based on the transfer matrix theory of photonic crystals. Multispectral films can achieve multi-band compatible protection well, but these materials often have defects such as poor high-temperature stability and complex preparation process and harsh process conditions, which limit their application.

[0004] Aerogels, possessing lightweight, high strength, high temperature resistance, and chemical stability, serve as templates for multispectral compatible materials used to overcome harsh environments. The Chinese Academy of Sciences (Chemical Engineering Journal 2024, 484) has prepared ordered heterostructure multispectral aerogels, achieving multi-band protection in the microwave, infrared, and visible light bands. The high-temperature resistance of silicon carbide makes it an ideal material for aerogel frameworks, and its unique structure plays an indispensable role in the field of lightweight, high-temperature resistant materials. Furthermore, silicon carbide materials exhibit good microwave absorption properties, making silicon carbide aerogels an ideal carrier for multispectral compatible protection. Harbin Institute of Technology (Composites Part B: Engineering 2023, 248) has prepared SiC / C aerogels, achieving good electromagnetic absorption capabilities. Achieving a lightweight, high-temperature resistant, and structurally functionally integrated approach is becoming a future trend in multispectral research, while simplifying the preparation process is a crucial factor driving the development of multispectral materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies by proposing a method for preparing lightweight cobalt-based multispectral silicon carbide aerogels for visible-near-infrared-microwave compatible protection. Using silicon carbide aerogels as templates, visible-near-infrared-microwave compatible protection is achieved through composite cobalt-based functional fillers.

[0006] The technical solution of this invention is: a method for preparing cobalt-based multispectral silicon carbide aerogel, the specific steps of which are as follows:

[0007] (1) Preparation of composite precursor suspension: Cobalt source, silicon carbide (SiC) and binder are thoroughly mixed in deionized water and stirred to form a uniform composite precursor suspension;

[0008] (2) Freeze-drying process: Pour the composite precursor suspension into a mold, place the mold on a cold surface at a constant low temperature for freezing, and then dry the frozen sample to remove ice crystals to obtain cobalt-based silicon carbide aerogel precursor.

[0009] (3) Heat treatment process: The cobalt-based silicon carbide aerogel precursor is subjected to high-temperature heat treatment to remove the binder, and a lightweight, cobalt-based multispectral silicon carbide aerogel material for visible light-near infrared-microwave compatible protection is obtained.

[0010] In preferred step (1), the mass concentrations of cobalt source, SiC and binder in the suspension are 10-30%, 60-80% and 2-5%, respectively.

[0011] The preferred cobalt source in step (1) is one or more of cobalt tetroxide, cobalt chromate, or cobalt aluminate.

[0012] The preferred SiC mentioned in step (1) is silicon carbide nanofibers (SiC nf ), silicon carbide nanowires (SiC) nw ) or silicon carbide nanoparticles (SiC) np One or more of them.

[0013] The preferred adhesive in step (1) is one or more of polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP).

[0014] The preferred freezing temperature in step (2) is -60 to -30°C.

[0015] The preferred heat treatment temperature in step (3) is 500-700℃, the heat treatment heating rate is 0.5-1℃ / min, and the holding time is 1-2h.

[0016] Beneficial effects:

[0017] Increasingly complex application scenarios place higher demands on protective materials, making lightweight and high-temperature resistant materials an inevitable trend in the development of multispectral protective materials. Traditional single-band protective materials struggle to adapt to more demanding application environments, while silicon carbide aerogels, possessing lightweight, high strength, high temperature resistance, and chemical stability, serve as templates for multispectral compatible materials to overcome harsh environments. The unique structure of silicon carbide aerogels makes them indispensable in the field of lightweight and high-temperature resistant materials. Furthermore, the microwave absorption properties of silicon carbide make silicon carbide aerogels an ideal carrier for multispectral compatible protection. Combining cobalt-based functional fillers with silicon carbide aerogels is an effective means of achieving multispectral compatible protection. Attached Figure Description

[0018] Figure 1 Visible-near-infrared reflectance curves of cobalt-based multispectral silicon carbide aerogel in Implementation Example 1;

[0019] Figure 2 Microwave absorption performance of cobalt-based multispectral silicon carbide aerogel in Implementation Example 1;

[0020] Figure 3 SEM image of cobalt-based multispectral silicon carbide aerogel in Example 1;

[0021] Figure 4 Thermal imaging of the cobalt-based multispectral silicon carbide aerogel spray gun in Implementation Example 1;

[0022] Figure 5 Lightweight photograph of cobalt-based multispectral silicon carbide aerogel in Implementation Example 1. Detailed Implementation

[0023] The present invention will now be further described with reference to the embodiments:

[0024] Example 1:

[0025] (1) Weigh out a certain mass of CoAl2O4 and SiC nf (Shanghai Aladdin Biochemical Technology Co., Ltd.), PVA, dissolved in deionized water and evenly dispersed to form a uniform composite precursor suspension, with mass fractions of 10%, 70% and 2% in the suspension, respectively.

[0026] (2) Pour the composite precursor suspension from step (1) into a polytetrafluoroethylene mold and place the mold on a cold surface at a constant low temperature of -60℃ for directional freezing;

[0027] (3) Freeze-dry the frozen sample from step (2) to remove ice crystals and obtain a cobalt-based multispectral silicon carbide aerogel precursor.

[0028] (4) The silicon carbide aerogel precursor in step (3) is placed in a muffle furnace for high-temperature heat treatment to obtain cobalt-based multispectral silicon carbide aerogel. The pyrolysis temperature is 500℃, the holding time is 2h, and the heating rate is 1℃ / min.

[0029] from Figure 1 It can be seen that cobalt-based multispectral silicon carbide aerogel has a blue reflection peak, a reflectance of more than 65% in the 800-900nm band, and exhibits near-infrared plateau characteristics. Figure 2 It can be seen that the bandwidth of the cobalt-based multispectral silicon carbide aerogel is 4GHz (8-12GHz), and the minimum reflection loss reaches -15dB, which shows that it has certain microwave absorption performance. This indicates that the prepared cobalt-based multispectral silicon carbide aerogel has good performance in the visible-near infrared-microwave band. Figure 3 SEM image of the prepared cobalt-based multispectral silicon carbide aerogel. Figure 4 This is a thermal image of cobalt-based multispectral silicon carbide aerogel at 342℃, demonstrating its high-temperature stability. Figure 5 This demonstrates the lightweight properties of aerogels.

[0030] Example 2:

[0031] (1) Weigh out a certain mass of Co3O4 and SiC nw (Shanghai Aladdin Biochemical Technology Co., Ltd.), PVP, dissolved in deionized water and evenly dispersed to form a uniform composite precursor suspension, with mass fractions of 20%, 60% and 5% in the suspension, respectively.

[0032] (2) Pour the composite precursor suspension from step (1) into a polytetrafluoroethylene mold and place the mold on a cold surface at a constant low temperature of -50℃ for directional freezing;

[0033] (3) Freeze-dry the frozen sample from step (2) to remove ice crystals and obtain a cobalt-based multispectral silicon carbide aerogel precursor.

[0034] (4) The precursor in step (3) is placed in a muffle furnace for high-temperature heat treatment to obtain cobalt-based multispectral silicon carbide aerogel. The pyrolysis temperature is 700℃, the holding time is 1h, and the heating rate is 0.5℃ / min.

[0035] The prepared cobalt-based multispectral silicon carbide aerogel has green and blue reflection peaks, and its reflectivity is greater than 60% in the 800-900nm band, exhibiting near-infrared plateau characteristics. The bandwidth of the cobalt-based multispectral silicon carbide aerogel is 4GHz (8-12GHz), with a minimum reflection loss of -13dB. This indicates that the prepared cobalt-based multispectral silicon carbide aerogel has good performance in the visible-near-infrared-microwave band, and the aerogel remains stable at 350℃.

[0036] Example 3:

[0037] (1) Weigh out a certain mass of CoAl2O4 and SiC np (Shanghai Aladdin Biochemical Technology Co., Ltd.), PVP, dissolved in deionized water and dispersed evenly to form a uniform composite precursor suspension, with mass fractions of 30%, 60% and 5% in the suspension, respectively.

[0038] (2) Pour the composite precursor suspension from step (1) into a polytetrafluoroethylene mold and place the mold on a cold surface at a constant low temperature of -50℃ for directional freezing;

[0039] (3) Freeze-dry the frozen sample from step (2) to remove ice crystals and obtain a cobalt-based multispectral silicon carbide aerogel precursor.

[0040] (4) The precursor in step (3) is placed in a muffle furnace for high-temperature heat treatment to obtain cobalt-based multispectral silicon carbide aerogel. The pyrolysis temperature is 700℃, the holding time is 1h, and the heating rate is 0.5℃ / min.

[0041] The prepared cobalt-based multispectral silicon carbide aerogel has green and blue reflection peaks, and its reflectivity is greater than 60% in the 800-900nm band, exhibiting near-infrared plateau characteristics. The bandwidth of the cobalt-based multispectral silicon carbide aerogel is 4GHz (8-12GHz), with a minimum reflection loss of -14dB. This indicates that the prepared cobalt-based multispectral silicon carbide aerogel has good performance in the visible-near-infrared-microwave band, and the aerogel remains stable at 350℃.

[0042] Example 4:

[0043] (1) Weigh out a certain mass of CoCrO4 and SiC nf (Shanghai Aladdin Biochemical Technology Co., Ltd.), PVA, dissolved in deionized water and evenly dispersed to form a uniform composite precursor suspension, with mass fractions of 10%, 70% and 3% in the suspension, respectively.

[0044] (2) Pour the composite precursor suspension from step (1) into a polytetrafluoroethylene mold and place the mold on a cold surface at a constant low temperature of -50℃ for directional freezing;

[0045] (3) Freeze-dry the frozen sample from step (2) to remove ice crystals and obtain a cobalt-based multispectral silicon carbide aerogel precursor.

[0046] (4) The SiC aerogel precursor in step (3) is placed in a muffle furnace for high-temperature heat treatment to obtain cobalt-based multispectral silicon carbide aerogel. The pyrolysis temperature is 600℃, the holding time is 2h, and the heating rate is 0.5℃ / min.

[0047] The prepared cobalt-based multispectral silicon carbide aerogel has a green reflection peak and a reflectivity greater than 60% in the 800-900 nm band, exhibiting near-infrared plateau characteristics. The bandwidth of the cobalt-based multispectral silicon carbide aerogel is 4 GHz (8-12 GHz), with a minimum reflection loss of -14.5 dB. This indicates that the prepared cobalt-based multispectral silicon carbide aerogel has good performance in the visible-near-infrared-microwave band, and the aerogel remains stable at 350 °C.

[0048] Example 5:

[0049] (1) Weigh out a certain mass of CoCrO4 and SiC nf (Shanghai Aladdin Biochemical Technology Co., Ltd.), PVA, dissolved in deionized water and evenly dispersed to form a uniform composite precursor suspension, with mass fractions of 20%, 60% and 5% in the suspension, respectively.

[0050] (2) Pour the composite precursor suspension from step (1) into a polytetrafluoroethylene mold and place the mold on a cold surface at a constant low temperature of -30℃ for directional freezing;

[0051] (3) Freeze-dry the frozen sample from step (2) to remove ice crystals and obtain a cobalt-based multispectral silicon carbide aerogel precursor.

[0052] (4) The silicon carbide aerogel precursor in step (3) is placed in a muffle furnace for high-temperature heat treatment to obtain cobalt-based multispectral silicon carbide aerogel. The pyrolysis temperature is 700℃, the holding time is 1h, and the heating rate is 1℃ / min.

[0053] The prepared cobalt-based multispectral silicon carbide aerogel has green and blue reflection peaks, and its reflectivity is greater than 60% in the 800-900nm band, exhibiting near-infrared plateau characteristics. The bandwidth of the cobalt-based multispectral silicon carbide aerogel is 4GHz (8-12GHz), with a minimum reflection loss of -15dB. This indicates that the prepared cobalt-based multispectral silicon carbide aerogel has good performance in the visible-near-infrared-microwave band, and the aerogel remains stable at 350℃.

Claims

1. A method for preparing cobalt-based multispectral silicon carbide aerogel, the specific steps of which are as follows: (1) Preparation of composite precursor suspension: The cobalt source, silicon carbide and binder are thoroughly mixed in deionized water and stirred to form a uniform composite precursor suspension; wherein the cobalt source is one of cobalt chromate or cobalt aluminate; the SiC is one or more of silicon carbide nanofibers, silicon carbide nanowires or silicon carbide nanoparticles; the binder is one of polyvinyl alcohol or polyvinylpyrrolidone. (2) Freeze-drying process: Pour the composite precursor suspension into a mold, place the mold on a cold surface at a constant low temperature for freezing, and then dry the frozen sample to obtain a cobalt-based silicon carbide aerogel precursor. (3) Heat treatment process: The cobalt-based silicon carbide aerogel precursor is subjected to high-temperature heat treatment to obtain cobalt-based multispectral silicon carbide aerogel material; wherein, The prepared cobalt-based multispectral silicon carbide aerogel has a reflectivity of ≥60% in the 800-900 nm band and a minimum reflection loss of ≤−13 dB in the 8–12 GHz band, so as to achieve visible light-near infrared-microwave compatible protection.

2. The preparation method according to claim 1, characterized in that: In step (1), the mass concentrations of cobalt source, SiC and binder in the suspension are 10~30%, 60~80% and 2~5%, respectively.

3. The preparation method according to claim 1, characterized in that: The freezing temperature mentioned in step (2) is -60~-30℃.

4. The preparation method according to claim 1, characterized in that: The heat treatment temperature in step (3) is 500~700℃, the heat treatment heating rate is 0.5~1℃ / min, and the holding time is 1~2h.

Images