Background technology
Usually, as a kind of electromagnetic wave absorbent material, in the wave frequency scope, material must have complex dielectric permittivity or complex permeability, and the imaginary part of the also imaginary part of complex dielectric permittivity or complex permeability wants enough big, if material has good complex dielectric permittivity and complex permeability simultaneously, this material just might be in very wide frequency range, absorb electromagnetic wave energy and convert it into other form of energy by dielectric loss and magnetic hystersis loss, thereby make the big high attenuation of electromagnetic wave signal by material.
At present, be widely used as the carbon black that has of electromagnetic wave dielectric loss material,,, improve the dielectric loss of material to increase the electric conductivity of material by in the nonconductive matrix material, adding carbon black.But this combined material is difficult to significantly improve the dielectric loss performance of material in actual applications, this is because the complex dielectric permittivity of material is difficult to significantly improve, and the carbon black in the composite can assemble, and causes the local display of material to go out the scrambling of conduction.1976, Japanese Atsushi Tomonaga and Tachikawa invented a kind of electromagnetic wave absorbent material (U.S Pat.No.3951904), and this material is to be composited by hollow carbon sphere and non-conducting material.In addition, (Sampe J.1991 for the retinyl Schiff's base salt that Stomier Roger A finds, 7/8:9), and conducting polymer composite such as polyacetylene, polypyrrole, polyaniline, polythiophene also can be used as the dielectric loss material, and the SiC ceramic material of Recent study has also demonstrated dielectric loss characteristics preferably.The dielectric loss material of more than enumerating has in various degree dielectric loss characteristics in the microwave high-frequency section, but most of material does not possess the magnetic hystersis loss characteristic.
The magnetic hystersis loss electromagnetic wave absorbent material, common have ferrite, metal powder, a nano-metal particle etc., these absorbents often have complex permeability preferably, but complex dielectric permittivity is unsatisfactory, and, metal material is than great, and anti-oxidant, poor corrosion resistance is restricted in actual applications.
Summary of the invention
Carbon covered metal or carbon metallization compound micro mist are a kind of novel nano-materials, but metal is when being transition metal or rare earth metal.Material has superior magnetism characteristic.Its architectural feature is that metal or metallic compound sodium rice particle are wrapped up by carbon and isolation mutually, and this new version makes it demonstrate good electricity, magnetic characteristic.The heat endurance of material and good corrosion resistance.Because the skin of micropowder material contains the C=C key, but material strong absorption infrared ray.
The purpose of this invention is to provide a kind of new electromagnetic wave absorbing material, this material is composited by carbon covered metal, carbon covered metal compound and host material, in microwave and infrared frequency range, have fine complex dielectric permittivity and complex permeability, can effectively absorb microwave and infrared energy.
Another object of the present invention provides the application of described electromagnetic wave absorbent material.
The objective of the invention is to realize by following measure:
The preparation of carbon covered metal, carbon covered metal compound micro mist can be adopted alternating current arc method (ZL 99 120144.2); Direct current arc method (Science, 1993,259,346; Jpn.J.Appl.Phys., 1994,33, L526) and other method (Chem.Phys.Letts, 1998,293,53; J.Mater.Chem., 2000,10,1971; J.Alloys and Compounds, 2002,333,308; J.Mater.Chem., 2000,10,715; J.Appl.Phys., 1998,11,6468; J.Appl.Phys., 1998,8,4409; Physics Letters A, 1999,254,65; Carbon, 2000,38,775; Materials research Bulletin, 1998,33[4], 663; ScriptaMaterialia, 2001,44,1583), wherein the alternating current arc method is one of effective method.By carbon covered metal, carbon covered metal compound micro mist that method for preparing goes out, its architectural feature is: metal or metal compound particles are wrapped up by outer carbon, and the size of micro mist is 50nm-10um, and metal or metal compound particles degree are 5nm-500nm.Micro mist has very high thermally-stabilised and chemical stability.
Carbon covered metal, carbon covered metal compound micro mist are distributed in the host material, are prepared into electromagnetic wave absorbent material.Host material can be selected organic material for use, as: paraffin, pitch, polystyrene, polyurethane, lucite, epoxy resin, polyphenyl ammonia, polypyrrole, various rubber and adhesive material also can be selected inorganic material for use, as: silicate, SiO
2
Metal in carbon covered metal, the carbon covered metal compound can be selected transition metal for use, as: Fe, Co, Ni, Mn, Ti also can select rare earth metal for use, as: Gd, Y, Nd, Sm.Metallic compound is metal carbides, nitride, oxide, sulfide.
Tenor is 5wt%-95wt% in synthetic carbon covered metal, metallic compound micro mist.
In the carbon covered metal electromagnetic wave absorbent material that is mixed with, carbon covered metal, the shared weight ratio of carbon covered metal compound micro mist are 5%-90%.
Carbon covered metal, carbon covered metal compound micro mist are distributed in the host material, make electromagnetic wave absorbent material of the present invention, its dielectric loss angle tangent tg δ
εCan reach 1.0, magnetic hystersis loss angle tangent tg δ
μCan reach 0.7, in the wave frequency scope, material surface reflection of electromagnetic wave rate reduces more than 90%.
The electromagnetic wave absorbent material that the present invention relates to has important application value; can be used as material obsorbing radar waves, infrared ray absorbing material, anti-electromagnetic radiation articles for labour protection; the electromagnetic shielding material of computer and communication equipment or device, mobile phone anti-electromagnetic radiation material.
The specific embodiment
In order to be illustrated more clearly in the present invention, enumerate the following example, but this there is not any restriction to the present invention.
Embodiment 1
Selecting iron content for use is the carbon iron clad micro mist of 70wt%, and host material is selected paraffin for use, micro mist/paraffin=1/1 (weight ratio), the complex dielectric permittivity of the microwave absorbing material that is mixed with and complex permeability are: 8.2GHz: ε '=14.44, and ε "=14.31; 10.0GHz: ε '=13.34, ε "=12.10, μ '=1.06, μ "=0.12; 12.0GHz: ε '=12.74, ε "=10.68.
Embodiment 2
Selecting iron content for use is the carbon iron clad micro mist of 80wt%, and host material is selected paraffin for use, micro mist/paraffin=4/1 (weight ratio), the complex dielectric permittivity of the microwave absorbing material that is mixed with and complex permeability are: 8.2GHz: ε '=28.5, and ε "=29.21; 10.0GHz: ε '=24.76, ε "=21.22, μ '=1.1, μ "=0.27; 12.0GHz: ε '=24.04, ε "=16.01; μ '=0.78, μ "=0.31; 15.0GHz: ε '=22.74, ε "=14.27, μ '=0.95, μ "=0.24; 18.0GHz: ε '=21.78, ε "=13.31; μ '=0.91, μ "=0.21.
Embodiment 3
Selecting iron content for use is the carbon iron clad micro mist of 70wt%, host material is selected paraffin for use, micro mist/paraffin=1/1 (weight ratio), the microwave absorbing material that is mixed with coats film forming on 300mm * 300mm aluminium sheet, the thickness of film is 1.3mm, and the flat reflective rate reduces 8-14dB in the 8Ghz-18GHz frequency range.
Need to prove that for one of ordinary skill in the art under the situation that does not change the principle of the invention, can also make some improvement or distortion to the present invention, this belongs to protection scope of the present invention equally.