Preparation method of wave-absorbing patch with temperature monitoring function

Abstract

The invention discloses a preparation method of a wave-absorbing patch with a temperature monitoring function, which comprises the following steps: by taking basswood as a raw material, carrying out pre-oxidation, oxidation, plasma treatment and immersion treatment to obtain the wave-absorbing patch with conductivity having a positive temperature coefficient. Different from a traditional resin-based or rubber-based wave-absorbing patch, the environment-friendly wave-absorbing patch has more excellent environment-friendly characteristic by adopting a biomass material, and meanwhile, the conductivity of the wave-absorbing patch prepared by the method is monotonically increased along with temperature rise, so that the characteristic can be applied to working temperature monitoring, and the safety threshold value of related equipment can be further improved. Besides, under the thickness of 2.0 mm, the vertical reflectivity of the prepared wave-absorbing patch in the frequency band of 12.5 GHz-18.0 GHz is smaller than-4dB, and the problem of electromagnetic mutual interference between electronic components in a narrow space can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to a method for preparing a microwave absorbing patch with temperature monitoring function. Background Technology With the integration and miniaturization of a large number of electronic devices, electromagnetic interference and heat generation from components will increase significantly in a smaller space. How to solve the electromagnetic interference between electronic components inside miniaturized equipment, improve the safety threshold of equipment use, and monitor the operating environment of important components inside the equipment are key issues that urgently need to be addressed.

[0002] To address the aforementioned issues and ensure the lifespan of equipment, many researchers have developed resin-based or rubber-based absorbing patches in conjunction with temperature sensors and other devices to eliminate electromagnetic interference while monitoring the operating temperature of components. However, these solutions introduce multiple materials or devices, which is not conducive to further miniaturization and weight reduction of equipment and does not meet the current development requirements for multifunctional integration of materials in electronic devices. Summary of the Invention

[0003] To obtain a material that integrates both electromagnetic protection and temperature monitoring functions, this invention provides an absorbing patch with temperature monitoring capabilities. Unlike traditional resin-based or rubber-based absorbing patches, this invention uses biomass-based materials, carbonizing linden wood chips and utilizing materials such as carbon black and carbon nanotubes to regulate both the absorption performance and the conductivity-temperature characteristics of the material. By utilizing the monotonic conductivity-temperature characteristics exhibited by the material over a wide temperature range, the temperature signal can be converted into an electrical signal, thereby enabling the monitoring of the operating temperature of the monitored device.

[0004] The technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned absorbing patch. This method can prepare a absorbing material with dual functions of absorbing waves and monitoring temperature. The preparation process is simple, low-cost, and has a wide range of applications, making it suitable for large-scale industrial production.

[0005] The present invention specifically adopts the following technical solution to solve the above-mentioned technical problems: a method for preparing an absorbing patch with temperature monitoring function, comprising the following steps: Step 1: Carbonization treatment of linden wood The linden wood is processed into boards, and after being cleaned and dried without ultrasonication, it is pre-oxidized and then carbonized into carbonized wood by gradient heating in an argon atmosphere. Step 2, plasma treatment of carbonized wood: The carbonized linden wood chips are subjected to plasma treatment; Step 3: Preparation of absorbing patch: Carbon black and carbon nanotubes were ultrasonically dispersed in anhydrous ethanol solvent to obtain a mixed solution. Plasma-treated linden wood chips were then impregnated in the mixed solution under negative pressure. After impregnation, the carbonized linden wood chips were removed and dried to obtain a microwave absorbing patch with temperature monitoring function.

[0006] Furthermore, in step 1, the ultrasonic cleaning time is 10 min to 30 min.

[0007] Furthermore, in step 1, the product is dried at 110°C for 1 to 4 hours.

[0008] Furthermore, in step 1, pre-oxidation is carried out in an air atmosphere at 180℃~270℃ for 9h~12h.

[0009] Furthermore, in step 1, the gradient heating carbonization in an argon atmosphere is carried out sequentially at 650℃, 675℃, 700℃ and 725℃.

[0010] Furthermore, in step 3, the negative pressure of the negative pressure environment is less than 0.09 MPa.

[0011] Furthermore, in step 3, the mass of carbon black is 0.1% to 1% of the mass of the solvent.

[0012] Furthermore, in step 3, the mass of the carbon nanotubes is 0.5% to 3% of the mass of the solvent.

[0013] Beneficial effects of the present invention This invention successfully integrates temperature monitoring and microwave absorption functions into a microwave absorbing patch prepared by controlling the carbonization temperature and the formulation and parameters of the vacuum impregnation adhesive. The microwave absorbing patch prepared by this invention, at a thickness of 2.0 mm, exhibits a vertical reflectivity of less than -4 dB in the 12.5 GHz to 18.0 GHz frequency band, effectively solving the problem of electromagnetic interference between electronic components in confined spaces. Simultaneously, the microwave absorbing patch exhibits a monotonic conductivity-temperature characteristic within the range of room temperature to 300°C, thus allowing a one-to-one correspondence between temperature and the patch's conductivity, and converting the temperature signal into an electrical signal to monitor the temperature of the patch's operating environment. Finally, the preparation method of this invention is simple, low-cost, requires no complex synthesis equipment, and can achieve large-scale mass production. Attached Figure Description

[0014] Figure 1a This is a scanning electron microscope image of the carbonized linden wood prepared in Example 1 before filling; Figure 1b This is a scanning electron microscope image of the carbonized linden wood prepared in Example 1 after filling; Figure 2A photograph of the absorbing patch with temperature monitoring function prepared in Example 1; Figure 3 The conductivity-temperature relationship of the absorbing patch with temperature monitoring function prepared in Example 1; Figure 4 Vertical reflectivity map of the absorbing patch with temperature monitoring function prepared in Example 1. Detailed Implementation

[0015] The disclosed examples will be described more fully with reference to the accompanying drawings, in which some (but not all) of the disclosed examples are shown. In fact, many different examples may be described, and these examples should not be construed as limited to those set forth herein. Rather, these examples are described so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0016] Example 1, in this example: Step 1: Process the linden wood into a cuboid with a side length of 30mm and a thickness of 2.5mm. After cleaning without ultrasonication for 18min, dry it at 110℃ for 4h, pre-oxidize it in air at 180℃ for 12h, and carbonize it in argon at 725℃ for 5h. The heating rate is 3℃ / min. Step 2: Perform plasma treatment on the carbonized linden wood chips for 15 seconds; Step 3: Using anhydrous ethanol as the solvent and weighing standard, weigh 1% carbon black and 3% carbon nanotubes. Disperse the carbon black and carbon nanotubes in the anhydrous ethanol solvent by ultrasonication for 4 hours. Impregnate the plasma-treated carbonized linden wood chips in the mixed solution of carbon black and carbon nanotubes, maintaining a negative pressure of less than 0.09 MPa during impregnation for 4 hours. After impregnation, remove the carbonized linden wood chips and dry them at 110℃ for 6 hours to obtain the microwave absorbing patch with temperature monitoring function.

[0017] Example 2, in this example: Step 1: Process the linden wood into a cuboid with a side length of 25mm and a thickness of 2.5mm. After cleaning without ultrasonication for 20 minutes, dry it at 110℃ for 4 hours, pre-oxidize it in air at 240℃ for 9 hours, and then carbonize it in argon at 675℃ for 4 hours. The heating rate is 3℃ / min. Step 2: Perform plasma treatment on the carbonized linden wood chips for 30 seconds; Step 3: Using anhydrous ethanol as the solvent and weighing standard, weigh 0.5% carbon black and 2% carbon nanotubes. Disperse the carbon black and carbon nanotubes in the anhydrous ethanol solvent by ultrasonication for 2 hours. Impregnate the plasma-treated carbonized linden wood chips in the mixed solution of carbon black and carbon nanotubes, maintaining a negative pressure of less than 0.09 MPa during impregnation for 2 hours. After impregnation, remove the carbonized linden wood chips and dry them at 110℃ for 6 hours to obtain the microwave absorbing patch with temperature monitoring function.

[0018] Example 3, in this example: Step 1: Process the linden wood into a cuboid with a side length of 20mm and a thickness of 2.5mm. After cleaning without ultrasonication for 25 minutes, dry it at 110℃ for 4 hours, pre-oxidize it in air at 270℃ for 12 hours, and then carbonize it in argon at 700℃ for 4 hours. The heating rate is 3℃ / min. Step 2: subject the carbonized linden wood chips to plasma treatment for 25 seconds; Step 3: Using anhydrous ethanol as the solvent and weighing standard, weigh 0.8% carbon black and 2.5% carbon nanotubes. Disperse the carbon black and carbon nanotubes in the anhydrous ethanol solvent by ultrasonication for 3 hours. Impregnate the plasma-treated carbonized linden wood chips in the mixed solution of carbon black and carbon nanotubes, maintaining a negative pressure of less than 0.09 MPa during impregnation for 2 hours. After impregnation, remove the carbonized linden wood chips and dry them at 110℃ for 6 hours to obtain the microwave absorbing patch with temperature monitoring function.

[0019] Descriptions of various advantageous arrangements have been shown for illustrative and descriptive purposes, but such descriptions are not intended to be exclusive or limited to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different advantageous examples may describe different advantages compared to other advantageous examples. One or more examples have been selected and described in order to best illustrate the principles and practical application of the examples, and to enable those skilled in the art to understand that this disclosure contains various examples with various modifications suitable for the particular intended use.

Claims

1. A method for preparing an absorbing patch with temperature monitoring function, characterized in that, The steps include the following: Step 1: Carbonization treatment of linden wood The linden wood is processed into boards, and after being cleaned and dried without ultrasonication, it is pre-oxidized and then carbonized into carbonized wood by gradient heating in an argon atmosphere. Step 2, plasma treatment of carbonized wood: The carbonized linden wood chips are subjected to plasma treatment; Step 3: Preparation of absorbing patch: Carbon black and carbon nanotubes were ultrasonically dispersed in anhydrous ethanol solvent to obtain a mixed solution. Plasma-treated linden wood chips were then impregnated in the mixed solution under negative pressure. After impregnation, the carbonized linden wood chips were removed and dried to obtain a microwave absorbing patch with temperature monitoring function.

2. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: In step 1, dry at 110℃ for 1 to 4 hours.

3. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: In step 1, pre-oxidation is carried out in an air atmosphere at 180℃~270℃ for 9h~12h.

4. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: In step 1, the gradient heating carbonization in an argon atmosphere is carried out sequentially at 650℃, 675℃, 700℃ and 725℃.

5. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: In step 3, the negative pressure of the negative pressure environment is less than 0.09 MPa.

6. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: In step 3, the mass of carbon black is 0.1% to 1% of the mass of the solvent.

7. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: In step 3, the mass of carbon nanotubes is 0.5% to 3% of the mass of the solvent.

8. The method for preparing an absorbing patch with temperature monitoring function as described in claim 1, characterized in that: A method for preparing an absorbing patch with temperature monitoring function, characterized in that, in step 1, the ultrasonic cleaning time is 10 min to 30 min.

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