CN101723654A - Nano-grade spinel type ferrite high-frequency microwave absorbent and method for preparing same - Google Patents

Abstract

The invention provides a nano-grade spinel type ferrite high-frequency microwave absorbent and a method for preparing the same and belongs to the technical field of wave absorbing materials. The conventional spinel type ferrite has undesirable wave absorbing property in the Ku waveband, the distribution of components is nonuniform and the preparation cost is high. The chemical composition of the absorbent is ZnxCoyNi(1-x-y)Fe2O4, wherein x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0.25 and less than or equal to 0.75, and the grain size is between 30 and 60nm. The preparation method comprises the following steps of: mixing water soluble metallic salts of zinc, cobalt, nickel and iron and a precipitator in the presence of a surface active agent to obtain a precursor of the spinel type ferrite; and calcining the precursor to obtain the nano-grade spinel type ferrite high-frequency microwave absorbent. The absorbent of the invention has the advantages of good wave absorbing property in the Ku waveband and uniform distribution of the components; and the preparation method is simple and low in cost.

Description

A kind of nano-grade spinel type ferrite high-frequency microwave absorbent and preparation method thereof

Technical field

The invention belongs to the absorbing material technical field, be specifically related to a kind ofly have nano-grade spinel type ferrite microwave absorption of better absorbing property and preparation method thereof in Ku frequency range (12-18GHz).

Background technology

Current, along with the high-frequency electromagnetic broad application, the research of absorbing material more and more causes people's interest.On the one hand, absorbing material can be used for being coated on large-scale military weapon, thereby for example it is weakened to the radar wave reflection in the surface of aircraft, tank, warship, realizes stealthy purpose.On the other hand, the works better of the serious countermeasure set of electromagnetic pollution, and HUMAN HEALTH had very big harm, absorbing material can effectively weaken or eliminate these pollutions.Therefore, military affairs still be civilian on the research of absorbing material all be significant.

Spinel type ferrite is inhaled ripple frequency band broad because preparation is simple, with low cost, remains the absorbing material that is most widely used at present.

Among the Chinese patent CN 1521772A, reported a kind of hertzian wave wave-absorber with the preparation of Mn-Zn ferrite, it has good sorption to hertzian wave near 1GHz, and the maximum reflection coefficient can reach-40dB.

Chinese patent CN 1206204A has reported a kind of main electromagnetic wave absorb with the preparation of ferrite wave absorbing agent, and this material has extremely strong absorption characteristic to the hertzian wave of 0.6-5GHz frequency range.The maximum reflection coefficient can reach-20dB.

NiZnCu ferrospinel-paraffin the matrix material of preparation such as Alexandre R.Bueno, when thickness is 4.5mm, in the 8-12GHz frequency range, the maximum reflection coefficient can reach-above (the Alexandre R.Bueno of 30dB, MariaL.Gregori, MariaC.S.Nobrega.M-icrowave-absorbing properties of Ni _0.50-xZn _0.50-xMe _2xFe ₂O ₄(Me=Cu, Mn, Mg) ferrite-wax composite in X-band frequencies[J] .Journal of Magneti-sm and Magnetic Materials 320 (2008) 864-870.).

The NiFe of preparation such as T.Giannakopoulou ₂O ₄Spinel type ferrite has absorbing property preferably at X-band (8-12GHz), maximum absorption can reach-25dB (T.Giannakopoulou, L.Kompotiatis, A.Kontogeorgakos, G.Kordas.Microwave behav-ior of ferrites prepared via sol-gel method[J] .Journal of Magnetism and Magnetic Materials 246 (2002) 360-365.).

Spinel type ferrite prepared in above-mentioned patent and the document all has good absorbing property below 12GHz, but unsatisfactory at the absorbing property of Ku wave band.Patent or document all are to adopt solid phase method or Prepared by Sol Gel Method in addition, and solid phase method needs very high calcining temperature, easily causes type ferrite component skewness, and Prepared by Sol Gel Method process complexity, the cost height is unfavorable for suitability for industrialized production.

Summary of the invention

The objective of the invention is to solve the problems of the prior art, have nano-grade spinel type ferrite microwave absorption of better absorbing property and preparation method thereof in Ku frequency range (12-18GHz) and provide a kind of.

The chemical constitution of nano-grade spinel type ferrite high-frequency microwave absorbent provided by the present invention is Zn _xCo _yNi _(1-x-y)Fe ₂O ₄, wherein, 0≤x≤0.5,0.25≤y≤0.75, particle diameter is 30-60nm.

The present invention adopts coprecipitation method to prepare nano-grade spinel type ferrite high-frequency microwave absorbent, and concrete steps are as follows:

1) water-soluble metal salt of zinc, cobalt, nickel and iron is pressed Zn ²⁺, Co ²⁺, Ni ²⁺And Fe ³⁺Mol ratio x: y: (1-x-y): 2 are dissolved in the deionized water, are mixed with the solution A that total concentration of metal ions is 0.03-3mol/L, wherein, 0≤x≤0.5,0.25≤y≤0.75;

2) precipitation agent is dissolved in is mixed with in the deionized water and the isopyknic solution B of solution A, the consumption of precipitation agent is to make Zn in the step 1) ²⁺, Co ²⁺, Ni ²⁺And Fe ³⁺Metal ion precipitates the many 5-10% of required amount fully;

3) tensio-active agent is added in the deionized water, obtain the solution C that surfactant concentration is 0.0001-0.001mol/L;

4) under agitation condition, solution A and B are added in the solution C simultaneously, stir 2-24h after, still aging 2-24h obtains the presoma of spinel type ferrite, wherein the volume ratio of solution A, B and C is 1: 1: 2;

5) presoma is washed be 7 to filtrate pH value after, drying is ground, and in 500-900 ℃ of calcining 1-10h, obtains nano-grade spinel type ferrite high-frequency microwave absorbent again.

Wherein, the water-soluble metal salt of the zinc described in the step 1) is zinc nitrate, zinc sulfate or zinc chloride; The water-soluble metal salt of described cobalt is Xiao Suangu, rose vitriol or cobalt chloride; The water-soluble metal salt of described nickel is nickelous nitrate, single nickel salt or nickelous chloride; The water-soluble metal salt of described iron is iron nitrate, ferric sulfate or iron(ic) chloride.

Step 2) precipitation agent described in is one or more the mixing in sodium hydroxide, potassium hydroxide, yellow soda ash or the ammonium oxalate.

Tensio-active agent described in the step 3) is selected from one or more the mixing in diethanolamine, trolamine, aliphatic alcohol polyethenoxy (3) ether (AEO 3), aliphatic alcohol polyethenoxy (9) ether (AE09) or the Sodium dodecylbenzene sulfonate.

Compare with existing ferrite and preparation method thereof, the present invention has following beneficial effect:

1) the present invention is with soluble metallic salt and precipitation agent blend, help metal ion and precipitation agent precipitates by stoichiometric ratio, can effectively avoid component defective pockety, use tensio-active agent simultaneously, improve the dispersiveness of spinel type ferrite presoma precipitation particles.

2) the present invention is simple to operate, and cost is low, helps large-scale industrial production.

3) the prepared high frequency wave absorbing agent of the present invention has good absorbing property more than 12GHz.

Description of drawings

The nano-grade spinel type Co that Fig. 1, embodiment 1 are prepared _0.25Ni _0.75Fe ₂O ₄XRD figure.

The nano-grade spinel type Zn that Fig. 2, embodiment 2 are prepared _0.3Co _0.3Ni _0.4Fe ₂O ₄Microwave absorbing property figure.

The invention will be further described below in conjunction with the drawings and specific embodiments, but protection scope of the present invention is not limited to following embodiment.

Embodiment

Agents useful for same is analytical pure among the following embodiment.

Embodiment 1

1) with Co (NO ₃) ₂6H ₂O, Ni (NO ₃) ₂6H ₂O, Fe (NO ₃) ₃6H ₂O is dissolved in the deionized water by 0.25: 0.75: 2 (mol ratio), is mixed with 100mLCo ²⁺, Ni ²⁺And Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.0025mol/L, 0.0075mol/L and 0.02mol/L;

2) preparation 100mL NaOH concentration is the solution B of 0.084mol/L;

3) preparation 200mL trolamine concentration is the solution C of 0.0001mol/L;

4) under the effect of stirring, solution A and solution B while constant speed are poured in the solution C, continue to stir 2h, stop to stir the still aging 12h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 3h down at 700 ℃ then, obtains consisting of Co _0.25Ni _0.75Fe ₂O ₄, average grain size is the spinel type ferrite of 41nm.

This sample is mixed by weight 4: 1 with paraffin, make the coaxial rings sample, test it at 12-18GHz frequency range plural number relative magnetic permeability μ with vector network analyzer _rWith plural relative permittivity ε _r, absorbing property can be estimated by the reflection coefficient that following formula calculates:

$R=20\mathrm{Lg}\left|\frac{Z_{\mathrm{in}}-1}{Z_{\mathrm{ij}}+1}\right|,$ $Z_{\mathrm{in}}=\tanh \left(j\frac{2\mathrm{\π}}{c}\mathrm{fd}\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}\right)$

In the following formula: R is a reflection coefficient, Z _InBe the standard input resistance of material, f is electromagnetic frequency, and c is the light velocity, and d is a coat-thickness.

Calculation result shows that when ferrite paraffin coating thickness is 2.5mm the maximum reflection coefficient can reach-20dB near 14GHz, and the above bandwidth of-10dB can reach 2GHz.

Embodiment 2

1) with Zn (NO ₃) ₂6H ₂O, Co (NO ₃) ₂6H ₂O, Ni (NO ₃) ₂6H ₂O and Fe (NO ₃) ₃6H ₂O was by 0.3: 0.3: 0.4: 2 (mol ratios) are dissolved in the deionized water, are mixed with 100mLZn ²⁺, Co ²⁺, Ni ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.03mol/L, 0.03mol/L, 0.04mol/L and 0.2mol/L;

2) preparation 100mL KOH concentration is the solution B of 0.88mo l/L;

3) preparation 200mL AEO3 concentration is the solution C of 0.0005mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 5h, stop to stir the still aging 10h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 2h down at 900 ℃ then, obtains consisting of Zn _0.3Co _0.3Ni _0.4Fe ₂O ₄, average grain size is the spinel type ferrite of 52nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that when ferrite paraffin coating thickness is 2.5mm the maximum reflection coefficient can reach-30dB near 15GHz, and the above bandwidth of-10dB can reach 3GHz

Embodiment 3

1) with Zn (NO ₃) ₂6H ₂O, Co (NO ₃) ₂6H ₂O, Fe (NO ₃) ₃6H ₂O is dissolved in the deionized water by 0.25: 0.75: 2 (mol ratio), is mixed with 50mL Zn ²⁺, Co ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.05mol/L, 0.15mol/L and 0.4mol/L;

2) preparation 50mL Na ₂CO ₃Concentration is the solution B of 0.87mol/L;

3) preparation 100mL AEO3 concentration is the solution C of 0.0005mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 24h, stop to stir the still aging 2h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 2h down at 600 ℃ then, obtains consisting of Zn _0.25CO _0.75Fe ₂O ₄Average grain size is the spinel type ferrite of 30nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that the maximum reflection coefficient can reach-25dB near 13GHz when ferrite paraffin coating thickness is 2.5mm, and the above bandwidth of-10dB can reach 2.5GHz.

Embodiment 4

1) with Zn (NO ₃) ₂6H ₂O, Co (NO ₃) ₂6H ₂O, Ni (NO ₃) ₂6H ₂O, Fe (NO ₃) ₃6H ₂O was by 0.4: 0.3: 0.3: 2 (mol ratios) are dissolved in the deionized water, are mixed with 40mLZn ²⁺, Co ²⁺, Ni ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.12mol/L, 0.09mol/L, 0.09mol/L and 0.6mol/L;

2) preparation 40mL (NH ₄) ₂C ₂O ₄Concentration is the solution B of 1.26mol/L;

3) preparation 80mL AEO3 concentration is the solution C of 0.0005mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 24h, stop to stir the still aging 2h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 2h down at 750 ℃ then, obtains consisting of Zn _0.4CO _0.3Ni _0.3Fe ₂O ₄, average grain size is the spinel type ferrite of 43nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that the maximum reflection coefficient can reach-22dB near 13.5GHz when ferrite paraffin coating thickness is 2.5mm, and the above bandwidth of-10dB can reach 2.3GHz.

Embodiment 5

1) with Zn (NO ₃) ₂6H ₂O, Co (NO ₃) ₂6H ₂O, Ni (NO ₃) ₂6H ₂O, Fe (NO ₃) ₃6H ₂O is by 0.4: O.3: be dissolved in deionized water, be mixed with 40mLZn at 0.3: 2 ²⁺, Co ²⁺, Ni ²⁺, Fe ³⁺Concentration is respectively 0.12mol/L, 0.09mol/L, the metal salt solution A of 0.09mol/L and 0.6mol/L;

2) preparation 40mL Na ₂CO ₃Concentration is the solution B of 1.32mol/L;

3) preparation 80mL Sodium dodecylbenzene sulfonate concentration is the solution C of 0.0005mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 4h, stop to stir the still aging 24h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 2h down at 800 ℃ then, obtains consisting of Zn _0.4CO _0.3Ni _0.3Fe ₂O ₄, average grain size is the spinel type ferrite of 46nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that the maximum reflection coefficient can reach-18dB near 14.5GHz when ferrite paraffin coating thickness is 2.5mm, and the above bandwidth of-10dB can reach 1.5GHz.

Embodiment 6

1) with CoSO ₄7H ₂O, NiSO ₄7H ₂O, Fe ₂(SO ₄) ₃9H ₂O is dissolved in the deionized water by 0.75: 0.25: 2 (mol ratio), is mixed with 100mLCo ²⁺, Ni ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.0075mol/L, 0.0025mol/L and 0.02mol/L;

2) preparation 100mL NaOH concentration is the solution B of 0.086mol/L;

3) preparation 200mL trolamine concentration is the solution C of 0.0001mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 12h, stop to stir the still aging 12h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 3h down at 700 ℃ then, obtains consisting of Ni _0.75Co _0.25Fe ₂O ₄, average grain size is the spinel type ferrite of 45nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that when ferrite paraffin coating thickness is 2.5mm the maximum reflection coefficient can reach-22.5dB near 14.3GHz, and the above bandwidth of-10dB can reach 2.3GHz.

Embodiment 7

1) with ZnCl ₂1.5H ₂O, CoGl ₂6H ₂O, NiCl ₂6H ₂O, FeCl ₃By 0.3: 0.3: 0.4: 2 (mol ratios) were dissolved in the deionized water, are mixed with 50mL Zn ²⁺, Co ²⁺, Ni ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.06mol/L, 0.06mol/L, 0.08mol/L and 0.4mol/L;

2) preparation 50mL Na ₂CO ₃Concentration is the solution B of 0.85mol/L;

3) preparation 100mL AEO9 concentration is the solution C of 0.0005mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 2h, stop to stir the still aging 10h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 1h down at 900 ℃ then, obtains consisting of Zn _0.3Co _0.3Ni _0.4Fe ₂O ₄, average grain size is the spinel type ferrite of 45nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that when ferrite paraffin coating thickness is 2.5mm the maximum reflection coefficient can reach-29dB near 15.5GHz, and the above bandwidth of-10dB can reach 3.0GHz

Embodiment 8

1) with Zn (SO ₄) ₂7H ₂O, Co (SO ₄) ₂7H ₂O, Fe (NO ₃) ₃9H ₂O is dissolved in the deionized water by 0.25: 0.75: 2 (mol ratio), is mixed with 100mL Zn ²⁺, Co ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.0025mol/L, 0.0075mol/L and 0.02mol/L;

2) preparation 100mL Na ₂CO ₃Concentration is the solution B of 0.043mol/L;

3) preparation 200mL trolamine concentration is the solution C of 0.0001mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 24h, stop to stir the still aging 2h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 5h down at 900 ℃ then, obtains consisting of Zn _0.25CO _0.75Fe ₂O ₄, average grain size is the spinel type ferrite of 60nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that the maximum reflection coefficient can reach-20dB near 12.5GHz when ferrite paraffin coating thickness is 2.5mm, and the above bandwidth of-10dB can reach 2GHz.

Embodiment 9

1) with Zn (NO ₃) ₂6H ₂O, Ni (NO ₃) ₂6H ₂O, Co (SO ₄) ₂7H ₂O, Fe ₂(SO ₄) ₃9H ₂O was by 0.4: 0.3: 0.3: 2 (mol ratios) are dissolved in the deionized water, are mixed with 100mL Zn ²⁺, Co ²⁺, Ni ²⁺, Fe ³⁺Concentration is followed successively by the metal salt solution A of 0.04mol/L, 0.03mol/L, 0.03mol/L and 0.2mol/L;

2) preparation 100mL KOH concentration is the solution B of 0.85mol/L;

3) preparation 200mL AEO3 concentration is the solution C of 0.0005mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 5h, stop to stir the still aging 10h in back, obtain the presoma of spinel type ferrite.

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 10h down at 500 ℃ then, obtains consisting of Zn _0.4CO _0.3Ni _0.3Fe ₂O ₄, average grain size is the spinel type ferrite of 55nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that the maximum reflection coefficient can reach-23dB near 13.9GHz when ferrite paraffin coating thickness is 2.5mm, and the above bandwidth of-10dB can reach 2.5GHz.

Embodiment 10

1) with Zn (NO ₃) ₂6H ₂O, CoCl ₂6H ₂O, NiCl ₂6H ₂O, Fe (NO ₃) ₃9H ₂O was by 0.5: 0.3: 0.2: 2 (mol ratios) are dissolved in the deionized water, are mixed with 100mL Zn ²⁺, Co ²⁺, Ni ²⁺, Fe ³⁺Concentration is followed successively by 0.5mol/L, 0.3mo l/L, the metal salt solution A of 0.2mol/L and 2mol/L;

2) preparation 100mL KOH concentration is the solution B of 8.5mol/L;

3) preparation 200mL AEO9 concentration is the solution C of 0.001mol/L;

4) under the state that constantly stirs, solution A and solution B while constant speed are poured in the solution C, continue to stir 4h, stop to stir the still aging 24h in back, obtain the presoma of spinel type ferrite;

5) the washing presoma equals 7 to filtrate pH, and drying is ground, and calcines 5h down at 800 ℃ then, obtains consisting of Zn _0.5CO _0.3Ni _0.2Fe ₂O ₄Average grain size is the spinel type ferrite of 50nm.

Electromagnetic parameter testing and reflection coefficient calculating method are the same, and calculation result shows that the maximum reflection coefficient can reach-19dB near 14.8GHz when ferrite paraffin coating thickness is 2.5mm, and the above bandwidth of-10dB can reach 1.6GHz.

Claims (8)

1. a nano-grade spinel type ferrite high-frequency microwave absorbent is characterized in that, the chemical constitution of described absorption agent is Zn _xCo _yNi _(1-x-y)Fe ₂O ₄, wherein, 0≤x≤0.5,0.25≤y≤0.75, particle diameter is 30-60nm.

2. the preparation method of the described a kind of nano-grade spinel type ferrite high-frequency microwave absorbent of claim 1 is characterized in that, may further comprise the steps:

1) water-soluble metal salt of zinc, cobalt, nickel and iron is pressed Zn ²⁺, Co ²⁺, Ni ²⁺And Fe ³⁺Mol ratio x: y: (1-x-y): 2 are dissolved in the deionized water, are mixed with the solution A that total concentration of metal ions is 0.03-3mol/L, wherein, 0≤x≤0.5,0.25≤y≤0.75;

2) precipitation agent is dissolved in is mixed with in the deionized water and the isopyknic solution B of solution A, the consumption of precipitation agent is to make Zn in the step 1) ²⁺, Co ²⁺, Ni ²⁺And Fe ³⁺Metal ion precipitates the many 5-10% of required amount fully;

3) tensio-active agent is added in the deionized water, obtain the solution C that surfactant concentration is 0.0001-0.001mol/L;

4) under agitation condition, solution A and B are added in the solution C simultaneously, stir 2-24h after, still aging 2-24h obtains the presoma of spinel type ferrite, wherein the volume ratio of solution A, B and C is 1: 1: 2;

5) presoma is washed be 7 to filtrate pH after, drying is ground, and in 500-900 ℃ of calcining 1-10h, obtains nano-grade spinel type ferrite high-frequency microwave absorbent again.

3. preparation method according to claim 2 is characterized in that, the water-soluble metal salt of the zinc described in the step 1) is zinc nitrate, zinc sulfate or zinc chloride.

4. preparation method according to claim 2 is characterized in that, the water-soluble metal salt of the cobalt described in the step 1) is Xiao Suangu, rose vitriol or cobalt chloride.

5. preparation method according to claim 2 is characterized in that, the water-soluble metal salt of the nickel described in the step 1) is nickelous nitrate, single nickel salt or nickelous chloride.

6. preparation method according to claim 2 is characterized in that, the water-soluble metal salt of the iron described in the step 1) is an iron nitrate, ferric sulfate or muriate iron.

7. preparation method according to claim 2 is characterized in that step 2) described in precipitation agent be one or more mixing in sodium hydroxide, potassium hydroxide, yellow soda ash or the ammonium oxalate.

8. preparation method according to claim 2 is characterized in that, the tensio-active agent described in the step 3) is selected from one or more the mixing in diethanolamine, trolamine, AE03, AE09 or the Sodium dodecylbenzene sulfonate.

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