CN109005660B - Cobalt nano-particle and redox graphene electromagnetic wave absorbent material preparation method - Google Patents
Cobalt nano-particle and redox graphene electromagnetic wave absorbent material preparation method Download PDFInfo
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- CN109005660B CN109005660B CN201811028131.5A CN201811028131A CN109005660B CN 109005660 B CN109005660 B CN 109005660B CN 201811028131 A CN201811028131 A CN 201811028131A CN 109005660 B CN109005660 B CN 109005660B
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Abstract
The present invention provides a kind of cobalt nano-particle and redox graphene electromagnetic wave absorbent material preparation method, belongs to electromagnetic wave absorbent material preparation technical field.This method uses cobaltous sulfate as cobalt source or presoma, and sodium borohydride is as reducing agent and using ammonium hydroxide as precipitating reagent.Using the wet chemistry method of titration reduction, magnetic metal cobalt nano-particle is obtained.Then obtained magnetic metal nano particle and redox graphene are dispersed under ultra-high frequency ultrasonic wave, the electromagnetic wave absorbent material is made.The electromagnetic wave absorbent material is about 200nm or so by diameter, surface oxidation magnetic metal cobalt nano-particle and redox graphene form, magnetic metal cobalt is uniformly dispersed with redox graphene, magnetic metal cobalt nano-particle can be dispersed in the interlayer of redox graphene, form the structure of stratiform.The compound has small density, good dispersion, method easy, can be used as good frequency electromagnetic waves absorbing material.
Description
Technical field
The present invention relates to electromagnetic wave absorbent material preparation technical field, a kind of cobalt nano-particle and reduction-oxidation are particularly related to
Graphene electromagnetic wave absorbent material preparation method.
Background technique
With the rapid development of electron and information technology, it is various digitlization, high frequency electronic and electrical equipment at work
The electromagnetic wave of a large amount of different frequencies has been radiated to space, so as to cause new environmental pollution --- Electromagnetic Interference and radio frequency or
Radio interference.At the same time, electronic component is also just towards miniaturization, lightweight, digitlization and high-density integrated direction
Development, it is also higher and higher to sensitivity requirement, and be highly susceptible to outside electromagnetic interference and occur malfunction, image obstacle and
The problems such as voice disorder.The electromagnetic interference that electromagnetic radiation generates not only influences the performance realization of electronic product, but also therefrom
Caused electromagnetic pollution can cause serious harm to the mankind and other organisms.In addition various high-grade, precision and advanced on future battlefield
Strategic weapons system equally faces severe threat.As one of big military technological innovation of the present age three, stealth technology has become
Sea, land and sky, day, electromagnetism five in one three-dimensional modernized war in most important, most effective air defense penetration tactics technical measures,
It is to improve weapon system existence, prominent anti-and indispensable deep strike ability means.Stealth technology refers to be visited in certain remote sensing
The detectivity for reducing target is surveyed in environment, thus the technology for making it be difficult to be found in a wavelength range.Electromagnetic wave is inhaled
The most important thing that material has become various countries' research as the core of stealth technology is received, by the height weight of each military power, the world
Depending on.To sum up we can be found that no matter in civilian or military affairs, electromagnetic wave absorption material all has its special strategic position,
It is the extremely critical technology concerning national economy.
Existing electromagnetic wave absorbent material technology and there are problem wave absorbing agents mainly ferrite, polycrystalline iron fiber, conductive poly-
Close object, ceramic absorbent, magnetic metal micro mist and functional fibre.Ceramic absorbent high temperature resistant, corrosion-resistant, the coefficient of expansion is low, changes
It is good to learn stability, but its absorption intensity is lower.Polycrystalline iron fiber and the wide absorbing property of magnetic metal micro mist absorption band, no
Cross its poor corrosion resistance.Conducting polymer is homogeneous, easily processed into type, density is small, electromagnetic parameter is adjustable, the disadvantage is that making
It is small with temperature range.Ferrite absorbent is high-efficient, coating is thin, bandwidth, is most common microwave absorption, and shortcoming is close
Degree is big, the weight gain of temperature stability official post component can not be realized all good so that influencing component capabilities in the frequency used
Matching.
Magnetic metal cobalt is as a kind of important metallicl magnetic material, saturation magnetization with higher and biggish magnetic
Anisotropy value, but its electromagnetic wave absorption performance is ideal not to the utmost.Although its inhale intensity of wave it is big, effectively absorb frequency range it is narrow, to low
The absorption of frequency area is weaker to be restricted its practical application.Graphene is a kind of typical two-dimensional material, since it is single with a thickness of one
Atomic layer and special hole wall are allowed to possess lightweight, good electric conductivity, bigger serface and biggish dielectric constant
Etc. characteristics.But it has been observed that its high conductivity makes impedance matching special when reduced graphene is used alone as absorbing material
Property it is poor, although can achieve wider frequency rate absorption, inhale intensity of wave down to the requirement less than absorbing material.Therefore, it will restore
The magnetic metal material of graphene oxide and metallic cobalt etc is compound, obtains a kind of new composite material.Resistance damage can be played
Multiband, high efficiency electromagnetic wave absorption are realized in the synergistic effect of consumption and magnetic loss, the impedance matching and absorbing property for improving material,
Also it is able to satisfy that coating is thin simultaneously, the small requirement redox graphene of density makes it realize that excellent electromagnetic wave is inhaled in high frequency band
Receipts are possibly realized.Studies have shown that electro-magnetic wave absorption intensity, absorption frequency, absorber thickness and absorption band width and magnetism gold
The microstructure for belonging to cobalt has close relationship.
The method for preparing magnetic metal nano particle Yu redox graphene composite wave-suction material at present, generalling use is
Hydro-thermal method or thermal decomposition method, preparation condition is complex, complex for operation step, and energy consumption is high, and the composite material obtained
It is not carried out the multiband to electromagnetic wave, wideband is strong to absorb.For example, Zhao et al. coats iron nano-particle on the surface of graphene
Graphene/Fe composite wave-suction material is made, obtains the absorption maximum bandwidth (RL < -10dB) of 4.4GHz simultaneously when with a thickness of 2.0mm
And maximum obtains maximum reflection loss -45dB, referring to Sci.Rep.2013,3,3421 in 7.1GHz.Liu et al. synthesis
RGO/Co3O4Composite wave-suction material obtains maximum reflection loss value -43.7dB in 13.8GHz.The electromagnetic wave absorbent material is effective
It absorbs bandwidth and reaches 4.6GHz when with a thickness of 3.3mm, referring to Mater.Lett.2013,107,166.Fu et al. passes through simple
Vapor diffusion processes graphene/hollow sphere CoFe has been synthesized with calcination method2O4Nanocomposite.The nano combined material of preparation
The maximum reflection loss of material reaches -18.5dB, and in addition effective Absorber Bandwidth is 3.7GHz when with a thickness of 2.0mm, referring to
J.Mater.Chem.A2014,2,735.Surface oxidation magnetic metal cobalt nano-particle and reduction is made using two-step method in the present invention
It graphene oxide graphene composite wave-suction material and applies in the electro-magnetic wave absorption within the scope of high-frequency 2-18GHz, it can be real
Now to the multiband of electromagnetic wave, wideband is strong to absorb.
Summary of the invention
The present invention provides one for deficiency existing for simple metals cobalt nano-particle electromagnetic wave absorbent material in the prior art
Kind cobalt nano-particle and redox graphene electromagnetic wave absorbent material preparation method.This method uses two-step method synthetic surface oxygen
Change magnetic metal cobalt nano-particle and redox graphene composite wave-suction material.Firstly, titrating reduction system by wet chemistry method
Standby surface oxidation magnetic metal cobalt nano-particle.Then the surface oxidation prepared previous step from mixed method using ultra-high frequency ultrasonic wave
Magnetic metal cobalt nano-particle is dispersed on redox graphene interlayer and surface.After ultrasonic disperse, centrifugation point
There is absorption intensity height, covering from metal cobalt nano-particle and redox graphene composite electromagnetic absorption absorbing material is obtained
The features such as wide frequency range, absorber thickness be thin, lightweight, simple and at low cost preparation process.
This method specifically includes that steps are as follows:
(1) in molar ratio (1-1.5) by presoma and reducing agent: (2-4), which is dissolved in respectively in deionized water, is made presoma
Solution and reducing agent solution；Then configured reducing agent solution is uniformly mixed with precipitating reagent by magnetic agitation, is gone back
The homogeneous mixture solotion of former agent and precipitating reagent；
(2) precursor solution obtained in step (1) is kept into magnetic agitation at 30-60 DEG C in thermostat water bath, together
When the homogeneous mixture solotion of reducing agent and precipitating reagent obtained in step (1) is titrated to presoma with the rate of (1-5) drop/sec
In solution, until drop reaction terminates, product centrifugal drying obtains the magnetic metal cobalt nanometer of surface oxidation after fully reacting
Grain；
(3) by metal cobalt nano-particle obtained in step (2) and redox graphene (5-15) in mass ratio: 1
Ultrasonic disperse 2-6 hours in high frequency ultrasound machine, it is then centrifuged for isolating product and product is put into vacuum in vacuum oven
It is 4-6 hours dry, surface oxidation magnetic metal cobalt and redox graphene compound are obtained after the completion of dry.
Wherein, presoma is any one of cobaltous sulfate, cobalt chloride, cobalt nitrate in step (1), and precipitating reagent is ammonium hydroxide, also
Former agent is sodium borohydride or potassium borohydride.
The optimum mole ratio of presoma and reducing agent is 1:2 in step (1).
Precipitating reagent is generally the concentrated ammonia liquor of mass concentration 25%~28%.
The optimum temperature of titration reduction reaction is 35-50 DEG C in step (2), the homogeneous mixture solotion of reducing agent and precipitating reagent
Best titration speed into precursor solution is 1-2 drops/sec.
The usual mixed proportion of metal cobalt nano-particle and redox graphene is 5:1,10:1 and 15:1 in step (3)
Any one of, wherein optimum mixture ratio example is 5:1, and high frequency ultrasound jitter time is 4-6 hours.
Surface oxidation magnetic metal cobalt obtained and redox graphene compound are for making 2- in step (3)
The electromagnetic wave absorbent material of 18GHz frequency range.
The magnetic metal cobalt nano-particle partial size of surface oxidation obtained is 200nm in step (2), and particle surface is magnetism
Co3O4Oxide layer, be magnetic metal cobalt inside particle.
The principle of the invention is as follows:
Surface oxidation magnetic metal cobalt nano-particle is prepared first with wet-chemical titration reduction.Reducing agent (sodium borohydride
Or potassium borohydride) with precipitating reagent (ammonium hydroxide) be mixed to form uniform solution.At a certain temperature, temperature constant magnetic stirring is instilled dropwise
Under presoma (cobaltous sulfate, cobalt nitrate or cobalt chloride, cobalt acetate) solution in.The OH of hydrolysis in ammonium hydroxide-Ion meeting and forerunner
Co in liquid solution2+Ion generates Co (OH)2Precipitating.The boron hydracid radical ion in reducing agent can be to the Co of generation simultaneously
(OH)2Precipitating is restored, and cobalt nano-particle is formed.As reaction endlessly carries out, the cobalt nano-particle of generation is continuous
Crystal growth is packed together and generates magnetic metal cobalt nano-particle.Since the reaction is under conditions of temperature constant magnetic stirring
Ensure that the stability of reaction, can effectively prevent metal cobalt nano-particle from further reuniting increase, makes the gold generated
Belong to cobalt particle to stablize in 200nm or so.It is to be carried out under aqueous conditions, and reaction process is along with play additionally, due to reaction
Strong stirring, the metal cobalt nano-particle unavoidably generated can be reacted with the oxygen in air or solution, make the metal generated
Cobalt nano-particle surface occurs oxidation and generates one layer of thin Co3O4Oxide layer.
Surface oxidation magnetic metal cobalt nano-particle and redox graphene are under the action of ultra-high frequency ultrasonic wave, nanometer
Particle can be dispersed on the interlayer and surface of redox graphene, which can cooperate with the magnetic gold of surface oxidation
Belong to cobalt nano-particle and redox graphene in magnetic property and electrical property and the excellent properties in structure, surface oxidation magnetic
Property metal cobalt nano-particle and redox graphene material prepare can be used in high-frequency range electromagnetic wave absorb, have
Excellent electromagnetic wave absorption performance and important practical application value, in addition, also having the characteristics that density is low, it is simple, inexpensive to prepare.
The application of surface oxidation magnetic metal cobalt nano-particle and redox graphene material of the present invention, specifically
It can be used as electromagnetic shielding material in one of following (1) radio communication system, the electromagnetism spoke of (2) anti-high frequency, microwave heating equipment
Material is penetrated and leaks, (3) construct the material of microwave dark room, (4) stealth technology material.
The advantageous effects of the above technical solutions of the present invention are as follows:
In above scheme, synthetic surface aoxidizes the work of magnetic metal cobalt nano-particle and redox graphene composite material
Skill does not need template and complicated hardware device simply, reacts mild no pollution to the environment and cost of manufacture is lower.Preparation
Surface oxidation magnetic metal cobalt nano-particle and redox graphene composite material have low density, magnetic property and dielectricity
The good advantage of energy.It is inhaled since this surface oxidation magnetic metal cobalt nano-particle and redox graphene electromagnetic wave absorb have
The characteristics of wave performance is good, absorption frequency coverage area is wide, absorber thickness is thin, light weight, can operate with radio communication system
The electromagnetic radiation and leakage of the equipment such as middle electromagnetic shielding, anti-high frequency and microwave heating, construction microwave dark room and stealth technology etc.
Field.The present invention mixed is dispersed successfully gram by the uniform of surface oxidation magnetic metal cobalt nano-particle and redox graphene
Defect of the simple magnetic metal cobalt as electromagnetic wave absorbent material is taken.By the magnetic loss for cooperateing with surface oxidation magnetic metal cobalt
With the dielectric loss of redox graphene, the electromagnetic wave absorption performance of the electromagnetic wave absorbent material is greatly improved.
Detailed description of the invention
Fig. 1 (a) is the field emission scanning electron microscope that the magnetic metal cobalt nano-particle of synthesis is reacted in the embodiment of the present invention 1
(FESEM) figure is (b) transmission electron microscope of metal cobalt nano-particle and redox graphene compound in the embodiment of the present invention 1
(TEM) figure；
Fig. 2 is the X-ray of surface oxidation metal cobalt nano-particle and reduced graphene composite material in the embodiment of the present invention 1
Powder diffraction spectrum；
Fig. 3 illustrates for the Raman spectrum of composite material obtained in the embodiment of the present invention 1；
Fig. 4 is the cobalt element xps energy spectrum figure of surface oxidation magnetic metal cobalt nano-particle in the embodiment of the present invention 1；
Fig. 5 is multiple for surface oxidation magnetic metal cobalt nano-particle in the embodiment of the present invention 1 and its with redox graphene
Close the hysteresis loop of object；
Fig. 6 is that surface oxidation metal cobalt nano-particle and redox graphene mass ratio are 5 in the embodiment of the present invention 1:
1, additive amount is reflection loss curve of 20% composite electromagnetic absorption material under different-thickness in paraffin；
Fig. 7 is that surface oxidation metal cobalt nano-particle and redox graphene mass ratio are 10 in comparative example 2 of the present invention:
1, additive amount is reflection loss curve of 20% composite electromagnetic absorption material under different-thickness in paraffin；
Fig. 8 is that surface oxidation metal cobalt nano-particle and redox graphene mass ratio are 15 in comparative example 3 of the present invention:
1, additive amount is reflection loss curve of 20% composite electromagnetic absorption material under different-thickness in paraffin.
Specific embodiment
To keep the technical problem to be solved in the present invention, technical solution and advantage clearer, below in conjunction with attached drawing and tool
Body embodiment is described in detail.
The present invention provides a kind of cobalt for deficiency existing for existing simple metals cobalt nano-particle electromagnetic wave absorbent material
Nano particle and redox graphene electromagnetic wave absorbent material preparation method.
This method specifically includes that steps are as follows:
(1) in molar ratio (1-1.5) by presoma and reducing agent: (2-4), which is dissolved in respectively in deionized water, is made presoma
Solution and reducing agent solution；Then configured reducing agent solution is uniformly mixed with precipitating reagent by magnetic agitation, is gone back
The homogeneous mixture solotion of former agent and precipitating reagent；
(2) precursor solution obtained in step (1) is kept into magnetic agitation at 30-60 DEG C in thermostat water bath, together
When the homogeneous mixture solotion of reducing agent and precipitating reagent obtained in step (1) is titrated to presoma with the rate of (1-5) drop/sec
In solution, until drop reaction terminates, product centrifugal drying obtains the magnetic metal cobalt nanometer of surface oxidation after fully reacting
Grain；
(3) by metal cobalt nano-particle obtained in step (2) and redox graphene (5-15) in mass ratio: 1
Ultrasonic disperse 2-6 hours in high frequency ultrasound machine, it is then centrifuged for isolating product and product is put into vacuum in vacuum oven
It is 4-6 hours dry, surface oxidation magnetic metal cobalt and redox graphene compound are obtained after the completion of dry.
Wherein, presoma used is any one of cobaltous sulfate, cobalt chloride, cobalt nitrate, and precipitating reagent is ammonium hydroxide, reducing agent
For sodium borohydride or potassium borohydride.
It is explained combined with specific embodiments below.
Embodiment 1
Surface oxidation magnetic metal cobalt nano-particle and redox graphene composite electromagnetic absorption material are by partial size
It is obtained in the surface oxidation magnetic metal cobalt nano-particle of 200nm or so with redox graphene ultrasonic disperse.
The magnetic metal cobalt nano-particle of surface oxidation titrates reduction method preparation by wet-chemical.Use cobaltous sulfate as forerunner
Body, sodium borohydride is as reducing agent, and 25%~28% ammonia spirit is as precipitating reagent.The first step prepares 100mL0.1mol/L's
The sodium borohydride solution of cobalt sulfate solution and 40mL0.05mol/L.Then by the 25% of the sodium borohydride solution of 40ml and 60ml
~28% ammonia spirit is uniformly mixed the stable dispersions of obtained reducing agent and precipitating reagent.Then, configured cobaltous sulfate is molten
Liquid is put into constant temperature magnetic force water-bath, keeps 40 DEG C of waters bath with thermostatic control, with 1600 revs/min of rate magnetic agitations.It will be configured
Sodium borohydride and ammonia spirit are instilled in cobalt sulfate solution dropwise with 1 drop/sec of rate, are stirred until continuing magnetic force after titration
Heat preservation 30min is mixed, guarantees that magnetic metal cobalt nano-particle surface being capable of one layer of Co of fully oxidized generation3O4Thin oxide layer.Such as Fig. 1
(a) it is field emission scanning electron microscope (FESEM) figure of the magnetic metal cobalt nano-particle of reaction synthesis, can observes and be generated
Nano particle can be uniformly distributed, although there is reunion in part, whole particle diameter distribution is in 200nm or so.Second step will generate
Surface oxidation magnetic metal cobalt nano-particle and redox graphene matched by the mass ratio of 5:1, be added it is suitable
The mixture is put into ultrasonic disperse 4 hours in high frequency ultrasound machine after ethanol solution, makes surface oxidation magnetic metal nanometer
Grain be blended by high-power ultrasonics be distributed between graphene layer on surface.After ultrasonic disperse is complete, it is centrifugated out surface
Magnetic metal cobalt nano-particle and redox graphene compound are aoxidized, the mixture is then put into vacuum oven constant temperature
60 DEG C drying 8 hours.Fig. 1 (b) is transmission electron microscope (TEM) figure of metal cobalt nano-particle and redox graphene compound,
It can be seen that surface oxidation magnetic metal cobalt nano-particle can be dispersed in graphene under the work of ultra-high frequency ultrasonic wave
Interlayer, nano grain surface can be reduced graphene oxide and uniformly coat.Fig. 2 be surface oxidation metal cobalt nano-particle with
The X-ray powder diffraction pattern of reduced graphene composite material is able to demonstrate that the nanometer that reduction preparation is titrated by wet-chemical
Grain is mainly the metallic cobalt of face-centered cubic configuration.Fig. 3 is that the Raman spectrum of the composite material illustrates, it can be seen that oxygen reduction fossil
The peak D of black alkene and the peak G, it was demonstrated that the presence of redox graphene.In addition, Co3O4The presence of characteristic peak also directly confirms cobalt
Nano grain surface Co3O4The presence of oxide layer.Fig. 4 is the xps energy spectrum figure of surface oxidation magnetic metal cobalt nano-particle, can be with
Confirm cobalt with Co0、Co2+、Co3+Valence state exists, and further demonstrates the presence of metal cobalt nano-particle and surface oxide layer.
With magnetic force vibrometer (VSM) test surfaces aoxidize magnetic metal cobalt nano-particle and with redox graphene group
At compound magnetic property, as shown in figure 5, the saturation magnetization of surface oxidation magnetic metal cobalt nano-particle reaches
58.95emu·g-1, surface oxidation magnetic metal cobalt nano-particle/redox graphene compound saturator intensity
32.86emug can be reached-1.Surface oxidation magnetic metal cobalt nano-particle and with redox graphene composition it is compound
The magnetic coercive force of object is respectively 42.03Oe and 38.57Oe, has excellent magnetic property.
Metal cobalt nano-particle/redox graphene composite electromagnetic absorption material obtained is mixed with paraffin
It is even, coaxial sample is made.Sample internal diameter 3.0mm outer diameter is 7.0mm with a thickness of 2.0mm.According to metal cobalt nano-particle/oxygen reduction
Graphite alkene composite electromagnetic absorption material difference of additive amount in paraffin obtains three groups of different samples, the loading of paraffin
The composite material adding proportion for being fixed on constant every group of 0.5g is respectively 10%, 15%, 20%, so that it is determined that total matter of sample
Amount.Then by full-automatic vector network parameter sweep-frequency measurement system (HP-8722ES), using axis reflector-transmission network method
Measure above three groups of sample electromagnetic parameters.As shown in fig. 6, passing through the reflection loss of the three kinds of samples of electromagnetic parameters measured
Energy.Wherein when metal cobalt nano-particle and redox graphene mass ratio are 5:1, have when additive amount is 20% in paraffin
Most excellent wave-sucking performance, when sample effectively inhales wave frequency under 1.8mm thickness, wide (RL < -10dB can absorb 90% electricity
Magnetic wave) 5.7GHz can be reached.In addition, its maximum reflection loss is also above -20dB.
Comparative example 2
The condition and method and embodiment 1 for preparing the cobalt nano-particle of surface oxidation are consistent.By the Surface Oxygen of generation
Change magnetic metal cobalt nano-particle and redox graphene is matched by the mass ratio of 10:1, suitable ethanol solution is added
The mixture is put into ultrasonic disperse 4 hours in high frequency ultrasound machine afterwards, passes through surface oxidation magnetic metal cobalt nano-particle
High-power ultrasonics blending be distributed between graphene layer on surface.After ultrasonic disperse is complete, it is centrifugated out surface oxidation magnetic
Property metal cobalt nano-particle and redox graphene mixture, then by the mixture be put into 60 DEG C of vacuum oven constant temperature it is dry
Dry 8h.
Surface oxidation magnetic metal cobalt nano-particle obtained is mixed with redox graphene compound with paraffin
Even that coaxial sample is made, sample internal diameter 3.0mm outer diameter 7.0mm is with a thickness of 2.0mm.Three groups are obtained according to the difference of paraffin additive amount
Different samples, the loading of paraffin are fixed on that 0.5g is constant, and every group of composite material adding proportion is respectively 10%, 15%,
20% so that it is determined that sample gross mass.Then full-automatic vector network parameter sweep-frequency measurement system (HP-8722ES) is used, is adopted
Above three groups of sample electromagnetic parameters such as embodiment 1 is measured with axis reflector-transmission network method.
As shown in fig. 7, passing through the reflection loss performance of the three kinds of samples of electromagnetic parameters measured.Wherein when metallic cobalt is received
Rice grain and redox graphene mass ratio are 10:1, have most excellent suction wave energy when additive amount is 20% in paraffin
Power, wave frequency wide (RL < -10dB can absorb 90% electromagnetic wave) is effectively inhaled under 1.8mm thickness when sample to reach
5GHz.In addition, its maximum reflection loss can be more than -40dB.
Comparative example 3
The condition and method and embodiment 1 for preparing the cobalt nano-particle of surface oxidation are consistent.By the Surface Oxygen of generation
Change magnetic metal cobalt nano-particle and redox graphene is matched by the mass ratio of 15:1, suitable ethanol solution is added
The mixture is put into ultrasonic disperse 4h in high frequency ultrasound machine afterwards, passes through surface oxidation magnetic metal nano particle high-power
Ultrasonic blending be distributed in graphene hierarchical structure on surface.After ultrasonic disperse is complete, it is centrifugated out surface oxidation magnetic
Property metal cobalt nano-particle and redox graphene mixture, then by the mixture be put into 60 DEG C of vacuum oven constant temperature it is dry
Dry 8h.
Surface oxidation magnetic metal cobalt nano-particle obtained is mixed with redox graphene compound with paraffin
Even that coaxial sample is made, sample internal diameter 3.0mm outer diameter 7.0mm is with a thickness of 2.0mm.Three groups are obtained according to the difference of paraffin additive amount
Different samples, the loading of paraffin are fixed on that 0.5g is constant, every group of composite material adding proportion is respectively 10%, 15%,
20% so that it is determined that sample gross mass.Then full-automatic vector network parameter sweep-frequency measurement system HP-8722ES is used, is used
Axis reflector-transmission network method measures above three groups of sample electromagnetic parameters such as embodiment 1.
As shown in figure 8, passing through the reflection loss performance of the three kinds of samples of electromagnetic parameters measured.Wherein when metallic cobalt is received
Rice grain and redox graphene mass ratio are 15:1, have most excellent suction wave energy when additive amount is 20% in paraffin
Power, wave frequency wide (RL < -10dB can absorb 90% electromagnetic wave) is effectively inhaled under 1.9mm thickness when sample to reach
4.9GHz.In addition, its maximum reflection loss is in -20dB or so.
The above is a preferred embodiment of the present invention, it is noted that for those skilled in the art
For, without departing from the principles of the present invention, several improvements and modifications can also be made, these improvements and modifications
It should be regarded as protection scope of the present invention.
Claims (8)
1. a kind of cobalt nano-particle and redox graphene electromagnetic wave absorbent material preparation method, it is characterised in that: including step
It is rapid as follows:
(1) in molar ratio (1-1.5) by presoma and reducing agent: (2-4), which is dissolved in respectively in deionized water, is made precursor solution
With reducing agent solution；Then configured reducing agent solution is uniformly mixed with precipitating reagent by magnetic agitation, obtains reducing agent
With the homogeneous mixture solotion of precipitating reagent；
(2) precursor solution obtained in step (1) is kept into thermostat water bath magnetic agitation at 30-60 DEG C, simultaneously will
The homogeneous mixture solotion of reducing agent and precipitating reagent obtained is titrated to precursor solution with the rate of (1-5) drop/sec in step (1)
In, until drop reaction terminates, product centrifugal drying obtains the magnetic metal cobalt nano-particle of surface oxidation after fully reacting；
(3) by metal cobalt nano-particle obtained in step (2) and redox graphene (5-15) in mass ratio: after 1 proportion,
Ethanol solution is added to be then centrifuged for isolating product and be put into product very ultrasonic disperse 2-6 hours in high frequency ultrasound machine
It is dried in vacuo 4-6 hours in empty drying box, surface oxidation magnetic metal cobalt is obtained after the completion of dry and redox graphene is multiple
Close object.
2. cobalt nano-particle according to claim 1 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: presoma is any one of cobaltous sulfate, cobalt chloride, cobalt nitrate in the step (1), and precipitating reagent is ammonium hydroxide, also
Former agent is sodium borohydride or potassium borohydride.
3. cobalt nano-particle according to claim 1 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: presoma and reducing agent molar ratio are 1:2 in the step (1).
4. cobalt nano-particle according to claim 2 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: the precipitating reagent is the concentrated ammonia liquor of mass concentration 25%~28%.
5. cobalt nano-particle according to claim 1 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: titration reduction reaction carries out at 35-50 DEG C in the step (2), and reducing agent and uniformly mixing for precipitating reagent are molten
Titration speed of the liquid into precursor solution is 1-2 drops/sec.
6. cobalt nano-particle according to claim 1 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: the mixed proportion of metal cobalt nano-particle and redox graphene is 5:1,10:1 and 15 in the step (3):
Any one of 1, high frequency ultrasound jitter time is 4-6 hours.
7. cobalt nano-particle according to claim 1 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: surface oxidation magnetic metal cobalt obtained is with redox graphene compound for making in the step (3)
The electromagnetic wave absorbent material of 2-18GHz frequency range.
8. cobalt nano-particle according to claim 1 and redox graphene electromagnetic wave absorbent material preparation method,
Be characterized in that: the magnetic metal cobalt nano-particle partial size of surface oxidation obtained is 200nm, particle surface in the step (2)
Be magnetic Co3O4Oxide layer, be magnetic metal cobalt inside particle.
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| CN112930101B (en) * | 2021-01-21 | 2022-03-22 | 北京航空航天大学 | Carbon-coated cobalt composite nano wave-absorbing material and preparation method thereof |
| CN113015422B (en) * | 2021-02-22 | 2022-04-15 | 山东大学 | Cobalt-nickel alloy/reduced graphene oxide nanocomposite for shielding high-frequency electromagnetic waves, and preparation method and application thereof |
| CN113258301B (en) * | 2021-05-14 | 2022-12-02 | 同济大学 | Composite material and preparation method and application thereof |
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