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Ferrite-nickle composite powder for electro-magnetism suction wave and preparation method

A technology of composite powder and electromagnetic absorption, which is applied to the parts, shielding, and instruments of instruments, can solve the problems of narrow frequency band and high density, and achieve the effect of broadband and high-efficiency electromagnetic absorption performance

Inactive Publication Date: 2008-12-24
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the traditional ferrite coating has the defects of narrow frequency band and high density

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Example 1: Preparation of ferrite-nickel composite powder by citric acid gel sol method

[0033] (1). Use citric acid to complex ferric nitrate and barium nitrate to prepare the precursor: by molar ratio Ba(NO 3 ) 2 : Fe(NO 3 ) 3 : citric acid=1: 12: 19 Weigh raw materials, add distilled water to dissolve, drip ammonia water to adjust the pH value of the solution to 7;

[0034] (2). Add nickel powder to the precursor solution obtained in step (1), and vibrate ultrasonically for 20 minutes. The mass ratio of ferrite to metal nickel composite powder is 1:5; the particle size of nickel powder is 0.5-5 μm;

[0035] (3). Place the solution obtained in step (2) in a 90°C water bath and stir for 4 to 5 hours until the liquid becomes a viscous gel;

[0036] (4). Put the sol prepared in step (3) in an oven at 120°C for 4 hours to obtain a dry gel;

[0037] (5). Heat the gel obtained in step (4) to 850° C. in a muffle furnace at a rate of 200° C. / h, and then cool naturally ...

Embodiment 2

[0038] Example 2: Preparation of ferrite-nickel composite powder by self-propagating method

[0039] (1). Use citric acid to complex ferric nitrate and barium nitrate to prepare the precursor: according to the stoichiometric ratio Ba(NO 3 ) 2 : Fe(NO 3 ) 3 : citric acid=1: 12: 19 Weigh raw materials, add distilled water to dissolve, drip ammonia water to adjust the pH value of the solution to 7;

[0040] (2). Add nickel powder to the precursor solution obtained in step (1), and vibrate ultrasonically for 15 minutes. The mass ratio of ferrite to metal nickel composite powder is 1:0.01; the particle size of nickel powder is 0.5-5 μm;

[0041] (3). Place the solution obtained in step (2) in a crucible and heat until the dry gel spreads and burns by itself;

[0042] (4). Put the burned powder in a muffle furnace and heat it up to 850°C at a rate of 200°C / h, then cool naturally to obtain the desired product.

Embodiment 3

[0043] Example 3: Preparation of ferrite-coated nickel particles by co-precipitation method

[0044] (1) Prepare FeCl separately 3 ·6H 2 O, FeCl 2 4H 2 O, NaOH solution; solution concentrations are: FeCl 3 ·6H 2 O (1mol / L), FeCl 2 4H 2 O (1mol / L), NaOH (3mol / L);

[0045] (2) Take Fe3+ and Fe 2+ Ratio 3:2 FeCl 3 solution, FeCl 2 The solutions are mixed, placed in a constant temperature water bath at 75°C, and nickel powder, nickel powder and Fe are added 3 o 4 The mass ratio is 1:0.5, and the particle size of nickel powder is 0.5-5 μm;

[0046] (3) Rapidly stir the solution described in (2) and at the same time drop NaOH solution to pH=13. Stir evenly at a temperature of 75°C until the reaction is complete;

[0047] (4) The product obtained in step (3) is washed with water, separated by a centrifuge, and dried in vacuum to obtain the desired product.

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Abstract

The invention relates to a ferrite-nickel compound powder used for electromagnetic wave-absorption and a preparation method thereof. Metallic nickel powder is taken as a matrix; a chemical method is adopted to prepare a product required by cladding ferrites on the surface of the nickel powder; the mass ratio of the ferrites to the nickel compound powder is between 1 to 5 and 1 to 0.01; the grain diameter of the nickel powder is 0.5 to 5 microns; the ferrites are ferrites of spinel type or ferrites of magneto plumbite type. Any method of the citrate sol-gel method, the self-propagating method or the coprecipitation method is adopted to prepare the product required. A compound powder material prepared by the invention has electromagnetic wave-absorption performance with broad band and high efficiency and can be prepared into wave-absorption coatings that are widely applied to various civilian and military wave-absorption fields.

Description

technical field [0001] The invention relates to a ferrite-nickel composite powder used for electromagnetic wave absorption and a preparation method. Background technique [0002] Environmental electromagnetic pollution caused by electromagnetic radiation affects human health, which has increasingly attracted the attention of various countries. Within the range covered by electromagnetic radiation, new environmentally friendly wave-absorbing materials are used to make the building itself have a certain ability to absorb electromagnetic waves, which can attenuate the intensity of environmental electromagnetic waves, effectively reduce electromagnetic environmental pollution, and reduce the harm of electromagnetic radiation to residents. [0003] Absorbing materials can be divided into structural type and coating type according to the molding process and bearing capacity. Structural absorbing materials have dual functions of carrying and reducing electromagnetic wave reflectio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G12B17/02
Inventor 张晏清张雄
Owner TONGJI UNIV
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