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Method for preparing activated carbon capable of absorbing electromagnetic waves

A technology of activated carbon and electromagnetic waves, which is applied in the manufacture of inductors/transformers/magnets, the magnetism of inorganic materials, circuits, etc., can solve the problems of not being able to fully utilize the wave-absorbing characteristics, large specific surface area, and low specific gravity, and achieve improved electromagnetic wave absorption characteristics, Effect of High Electromagnetic Wave Absorption Efficiency

Inactive Publication Date: 2014-06-25
CHANGZHOU ZHONGKE HAINA CARBON TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Nano-carbon black and carbon nanotubes show extremely strong wave-absorbing properties, but because the wave-absorbing efficiency is proportional to the amount of filler doping, and carbon black cannot be doped in large quantities because of its low specific surface area. exert its absorbing properties
Activated carbon has great application potential in the field of microwave absorption due to its rich pores and large specific surface area (~3000m2 / g). However, due to the skin effect of electromagnetic waves and the generally large particle size of activated carbon, its surface area mainly comes from The internal pores make it polarize with electromagnetic waves and then play a very small proportion of the surface area of ​​absorbing properties, so the currently reported data on the absorbing properties of activated carbon (reflectivity value is only -2 ~ -6dB) is far lower than the theoretical expected value

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] 100g of coal-based mesoporous activated carbon with a particle size below 800 mesh (18 microns) is used as the basic carrier. Mix and stir 20g ferric chloride, 10g polyvinyl alcohol, 40g ethylene glycol, 10g triethylamine, and 150g deionized water to form a homogeneous transparent liquid, add a small amount of ammonia water to adjust the pH value between 7 and 9, and Stand at constant temperature at 40°C for 24 hours to form a stable sol solution. Pour the sol solution into 100g of the weighed activated carbon powder, stir, place at room temperature for 12 hours, and then dry in an oven at 80-120°C to obtain a prefabricated material. Put the prefabricated material into a tubular atmosphere furnace for heating, nitrogen is the protective gas, the heating rate is 0.5°C / min, the temperature is raised to 350°C, and the temperature is kept at a constant temperature for 180 minutes, then hydrogen is introduced for reduction for 30 minutes, and then naturally cooled to room te...

Embodiment 2

[0017] 100g of petroleum coke mesoporous activated carbon with a particle size below 800 mesh (18 microns) is used as the basic carrier. With 100g nickel sulfate (NiSO 4 ·7H 2 O), 70g of modified starch, 30g of glycerol, 10g of ethylenediamine, and 300g of deionized water were mixed and stirred to dissolve into a homogeneous transparent liquid, and a small amount of ammonia water was added to adjust the pH value between 7 and 9, and the temperature was kept at 70°C After standing for 24 hours, a stable sol solution was formed. The sol solution was poured into 100 g of the weighed activated carbon powder, stirred, left at room temperature for 12 hours, and then dried in an oven at 120° C. to obtain a prefabricated material. Put the prefabricated material into a tubular atmosphere furnace for heating, nitrogen is the protective gas, the heating rate is 10°C / min, the temperature is raised to 500°C, and the temperature is kept constant for 60 minutes, then hydrogen is introduced...

Embodiment 3

[0019] 100g of coconut shell activated carbon with a particle size below 800 mesh (18 microns) is used as the basic carrier. Mix and stir 70g cobalt trichloride, 30g chitosan, 20g ethylene glycol, 10g diethylamine, and 150g deionized water to form a homogeneous transparent liquid, add a small amount of ammonia water to adjust the pH value between 7 and 9, and Stand at constant temperature at 90°C for 24 hours to form a stable sol solution. The sol solution was poured into 100 g of the weighed activated carbon powder, stirred, left at room temperature for 12 hours, and then dried in an oven at 100° C. to obtain a prefabricated material. Put the prefabricated material into a tubular atmosphere furnace for heating, nitrogen is the protective gas, the heating rate is 6°C / min, the temperature is raised to 450°C, and the temperature is kept constant for 60 minutes, then hydrogen is introduced for reduction for 60 minutes, and then naturally cooled to room temperature under the prote...

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Abstract

The invention discloses a method for preparing activated carbon capable of absorbing electromagnetic waves, belongs to the technical field of functional carbon materials, and particularly relates to a preparation method through which the special activated carbon with the strong magnetism and the large surface area can be prepared. According to the method, ultra-fine grinding, chemical activation, magnetic nanoparticle and metal nanoparticle loading and the like are conducted on raw materials for preparing the activated carbon or universal activated carbon, and then the activated carbon is prepared. The prepared activated carbon powder material has high electromagnetic wave absorption efficiency within the frequency range from 6 GHz to 18 GHz. A sample with the thickness of 2 mm is prepared by mixing and solidifying 8% of fillers and phenolic resin. Within the frequency range of 2 GHz to 18 GHz, the frequency is measured to be 6.1 GHz through the NRL-arc method when the intensity of electromagnetic waves which can be absorbed reaches -5 dB, the frequency is larger than 3.4 GHz when the intensity of electromagnetic waves which can be absorbed is lower than -10 dB, and therefore the activated carbon is good electromagnetic attenuation functional materials and can be used for radar stealth of military equipment or electromagnetic pollution control of civil architecture.

Description

technical field [0001] The invention belongs to the technical field of functional carbon materials, and in particular relates to a method for preparing special activated carbon with strong magnetism and large surface area. Background technique [0002] Electromagnetic wave absorbing materials are in great demand in the fields of radar stealth technology, electronic information security, and electromagnetic pollution prevention and control. Compared with traditional ferrite and carbonyl iron absorbers, carbon-based absorbers have the advantages of light weight, adjustable frequency range, and good compatibility with the organic phase interface of the matrix. Carbon-based wave-absorbing functional fillers include graphite powder, graphite nickel-plated powder, carbon black, carbon nanotubes, chopped carbon fibers, and activated carbon fibers. Graphite powder and nickel-plated graphite powder can only be used for electromagnetic wave absorption in the microwave band due to the...

Claims

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Application Information

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IPC IPC(8): H01F1/36H01F41/02H05K9/00
Inventor 刘军张涛
Owner CHANGZHOU ZHONGKE HAINA CARBON TECH
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