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Method for preparing high-performance wave-absorbing composite powder

A composite powder, high-performance technology, applied in the direction of radiation-absorbing coatings, coatings, etc., can solve the problems of absorbing materials that cannot meet the absorption frequency bandwidth, light weight, high density of ferrite, etc., and achieve improvement Coating effect, low density, effect of improving absorbing performance

Inactive Publication Date: 2010-03-10
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Ferrite material is currently the main electromagnetic absorbing material. However, a single ferrite has a high density, and it is difficult to meet the requirements of absorbing frequency bandwidth, light weight, and thin thickness when made of a single ferrite, and the cost is relatively high.
Carbonyl iron powder has stable microwave absorption performance and high microwave absorption efficiency in low frequency bands, but its density is high and it is easy to age

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Weigh 2.6134g of barium nitrate, 48.48g of ferric nitrate, and 54.6364g of citric acid, add distilled water to dissolve and mix, and then drop ammonia solution to adjust the pH value of the solution to 7. The solution was stirred in a water bath at 90° C., and 22.231 g of 800-mesh hollow microspheres and 1.1116 g of ethylene glycol were added during the stirring process. Stir the solution until it becomes a viscous colloid, and then put it in an oven for 8 hours at 120°C to obtain a dry gel. The gel is calcined in a muffle furnace, and the heating rate is 100°C / h for 100°C-400°C; 30°C / h for 400°C-610°C; and 50°C / h for 610°C-850°C. After 1 hour of heat preservation, the ferrite composite powder is obtained by cooling naturally and slowly. Mix the composite powder with 33.34g of carbonyl iron powder evenly to obtain the desired product. The waveguide method detects that the product can absorb 10dB in the 812GHz frequency band, and most of the wave absorption in the 13-1...

Embodiment 2

[0020] Weigh 2.163g of strontium nitrate, 48.48g of ferric nitrate, and 54.6364g of citric acid, add distilled water to dissolve and mix, and then drop ammonia solution to adjust the pH value of the solution to 7. The solution was stirred in a water bath at 90° C., and 55.5765 g of hollow microspheres of 1250 mesh and 0.0058 g of polyethylene glycol were added during the stirring process. Stir the solution until it becomes a viscous colloid, and then put it in an oven for 8 hours at 120°C to obtain a dry gel. The gel is calcined in a muffle furnace, the heating rate is 60°C / h to 850°C, and the temperature is kept for 2 hours, and the ferrite composite powder is obtained by natural slow cooling. Mix the composite powder with 50g carbonyl iron powder evenly to get the desired product. The waveguide method detects that the product can absorb 10dB in the 8-12GHz frequency band, and most of the wave absorption in the 13-18GHz frequency band is greater than 10dB. And more absorpti...

Embodiment 3

[0022] Weigh 8.7309g of cobalt nitrate, 24.2712g of nitric acid, and 25.2126g of citric acid, add distilled water to dissolve and then mix, and then drop ammonia solution to adjust the pH value of the solution to 7. The solution was stirred in a water bath at 80° C., and 3 g of closed-cell expanded perlite and 0.6 g of polyethylene glycol were added during the stirring process. Stir the solution until it becomes a viscous colloid, and then put it in an oven for 8 hours at 120°C to obtain a dry gel. The gel is calcined in a muffle furnace, the heating rate is 60°C / h to 850°C, and the temperature is kept for 2 hours, and the ferrite composite powder is obtained by natural slow cooling. Mix the composite powder with 2g carbonyl iron powder evenly to get the desired product. The waveguide method detects that the product can absorb 10dB in the 8-12GHz frequency band, and most of the wave absorption in the 13-18GHz frequency band is greater than 10dB. And more absorption peaks.

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Abstract

The invention belongs to the technical field of microwave absorbing material, and more particularly relates to a preparation method of high-performance wave-absorbing composite powder, comprising thesteps of: respectively adding distilled water into soluble metal nitrate, ferric nitrate and citric acid for dissolving, and then mixing the water solutions to prepare a precursor; dripping ammonia water solution to adjust the pH value of the mixed solution to be neutral; putting the solution into water bath with the temperature of 70-90 DEG C to be stirred, adding inorganic porous medium and modifying agent in the stirring process, stirring until the liquid is sticky colloid; drying the prepared colloidal sol for 7.5-8.5h at the temperature of 115-125 DEG C, and obtaining dried gel; putting the gel into a muffle furnace for calcining, heating up to 850 DEG C, preserving the temperature for 1-2h, naturally and slowly cooling, and obtaining ferrite composite powder; and finally, mixing thecomposite power and carbonyl iron powder, and then obtaining the needed product. The stoichiometric proportion among the nitrate, the ferric nitrate and the citric acid is 1: 12: 19 or 1: 2: 4, the ratio between the theoretical value of the ferrite and the mass of the modifying agent is 1: 0.1-1:0.05, the ratio between the theoretical value of the ferrite and the mass of the porous medium is 1: 0.2-1: 5, and the mass ratio between ferrite-porous medium composite power and the carbonyl iron powder is 1: 0.2-1: 5. Compared with the traditional product, the wave-absorbing powder improves the wave-absorbing performance, and has good covering effect and a certain function of heat insulation. Therefore, the method can be used for preparing building wave-absorbing paint.

Description

technical field [0001] The invention belongs to the technical field of microwave absorbing materials, and in particular relates to a preparation method of high-performance microwave-absorbing composite powder. Background technique [0002] Ferrite material is currently the main electromagnetic absorbing material. However, a single ferrite has a high density, and it is difficult to meet the requirements of absorbing frequency bandwidth, light weight, and thin thickness when made of a single ferrite, and the cost is relatively high. The carbonyl iron powder has stable microwave absorption performance and high microwave absorption efficiency in the low frequency band, but it has a high density and is easy to age. Hollow microspheres and expanded perlite are new wave-absorbing materials, which have the characteristics of light weight, porous, and cheap, and the hollow medium has the function of heat preservation. The research of this project shows that carbonyl iron powder has ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09D7/12C09D5/32
Inventor 邱琴张晏清张雄
Owner TONGJI UNIV
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