A hollow ferric oxide@air@carbon nanocomposite wave-absorbing material of egg yolk shell and its preparation method

A technology of ferroferric oxide and carbon nanocomposite, applied in shielding materials, electrical components, magnetic field/electric field shielding, etc., can solve problems affecting the normal operation of the immune system, leakage of secret electromagnetic signals, and increased risk of disease, and achieve easy Adjustable absorbing performance, low filling ratio, easy to synthesize in large quantities

Active Publication Date: 2022-04-08
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] In recent years, with the extensive development and application of communication equipment and electronic equipment, it has provided great convenience for human beings, but it has also caused considerable electromagnetic pollution. It will not only cause secret electromagnetic signal leakage and electromagnetic wave interference, but also make the human body Health is endangered, long-term exposure to high electromagnetic radiation pollution will affect the normal work of the immune system and increase the risk of disease

Method used

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  • A hollow ferric oxide@air@carbon nanocomposite wave-absorbing material of egg yolk shell and its preparation method
  • A hollow ferric oxide@air@carbon nanocomposite wave-absorbing material of egg yolk shell and its preparation method
  • A hollow ferric oxide@air@carbon nanocomposite wave-absorbing material of egg yolk shell and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] (1) Weigh 3.2436 g of ferric chloride hexahydrate, 7.0584 g of sodium citrate dihydrate and 2.1624 g of urea, dissolve them in 210 mL of deionized water in sequence, then add 1.8 g of polyacrylamide, and stir the solution at room temperature for 5 h until uniform After clarification, the polytetrafluoroethylene-lined autoclave was kept at 200°C for 10 hours, and the obtained black muddy product was washed 5 times with deionized water and 3 times with absolute ethanol, and dried at 60°C, which was hollow trioxide. Iron nanoparticles;

[0037] (2) Weigh 300 mg of hollow Fe3O4 nanoparticles and disperse in 150 mL of ethanol and 50 mL of deionized water mixed solution, ultrasonically disperse for 30 min, add 4 mL of concentrated ammonia water (25 wt / %), and stir mechanically for 5 min, add 1 mL of TEOS (tetraethyl orthosilicate), and add it once every 30 min, add 3 times in total, stir mechanically for 6 h, wash the obtained product with ethanol 5 times, and dry at 60°C to ...

Embodiment 2

[0046] The difference between Example 2 and Example 1 is that in step (5), the calcination temperature is 700°C, and the rest of the process conditions are identical, and the black product obtained in this example is named P-700.

[0047] The egg yolk shell hollow iron tetroxide@air@carbon nanocomposite absorbing material (P-700) prepared in this example is mixed with paraffin, the proportion of paraffin is 70wt%, and pressed in a special mold to have an outer diameter of 7.00 mm , a coaxial sample with an inner diameter of 3.04 mm and a thickness of about 2 mm. The mass fraction of the product is 30%. Use the N5224A vector network analyzer to test its electromagnetic parameters, and calculate the absorbing performance. The test frequency range is 2-18 GHz.

[0048] The variation curve of reflection loss of sample P-700 with frequency is shown as Figure 4 As shown, when the coating thickness is 3 mm, the maximum absorption intensity of the composite material can reach -27.7 d...

Embodiment 3

[0050] The difference between Example 3 and Example 1 is that in step (5), the calcination temperature is 800°C, and the rest of the process conditions are identical, and the black product obtained in this example is named P-800.

[0051] The egg yolk shell hollow iron tetroxide@air@carbon nanocomposite absorbing material (P-800) prepared in this example is mixed with paraffin, the proportion of paraffin is 70wt%, and it is pressed into a special mold with an outer diameter of 7.00 mm , a coaxial sample with an inner diameter of 3.04 mm and a thickness of about 2 mm. The mass fraction of the product is 30%. Use the N5224A vector network analyzer to test its electromagnetic parameters, and calculate the absorbing performance. The test frequency range is 2-18 GHz.

[0052] When the coating thickness is 5.5 mm, the maximum absorption intensity of the egg yolk shell hollow ferric oxide@air@carbon nanocomposite absorbing material prepared in this example can reach -25 dB, and the ef...

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Abstract

The present invention relates to the technical field of electromagnetic wave absorption, in particular to a hollow iron ferric oxide@air@carbon nanocomposite wave-absorbing material of egg yolk shell and a preparation method thereof, which comprises the following steps: (1) coating the surface of hollow iron ferric oxide nanoparticles Coated SiO 2 ; (2) Carboxylation modification on the surface; (3) In-situ growth of MIL-100(Fe) on the surface; (4) Calcination at high temperature under nitrogen atmosphere; (5) Heating and stirring in lye to remove SiO 2 After washing and drying, the egg yolk-shell hollow ferric oxide@air@carbon nanocomposite wave-absorbing material is obtained. The preparation method of the present invention is low in cost, green and safe, does not produce any toxic and harmful substances, has no secondary pollution, is easy to synthesize in large quantities, and has industrialization prospects; the egg yolk shell hollow ferric oxide@air@carbon obtained by the preparation method of the present invention Nanocomposite absorbing materials have the characteristics of thin thickness, light weight, low filling ratio, strong absorption, wide frequency band, and easy control of absorbing performance, and have broad application prospects.

Description

technical field [0001] The invention relates to the technical field of electromagnetic wave absorption, in particular to a metal-organic framework-derived hollow ferric iron tetroxide@air@carbon nanocomposite wave-absorbing material and a preparation method thereof. Background technique [0002] In recent years, with the extensive development and application of communication equipment and electronic equipment, it has provided great convenience for human beings, but it has also caused considerable electromagnetic pollution. It will not only cause secret electromagnetic signal leakage and electromagnetic wave interference, but also make the human body Health is endangered, long-term exposure to high electromagnetic radiation pollution will affect the normal work of the immune system and increase the risk of disease. In addition, as a technical device that uses electromagnetic waves to detect target positioning, radar also occupies an important position in the military field. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05K9/00
CPCH05K9/0073
Inventor 胡军杨华栋潘剑南
Owner ZHEJIANG UNIV OF TECH
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