Preparation And Stealth Property Of Neoprene/Ferrites Composite Film

Radar stealth is a kind of technology which can escape signals from radars and avoid being found, recognized and tracked or reduce the probability being detected. In all of microwave absorbers, ferrites have stronger absorption and wider absorbing frequency bands. Therefore, ferrites are being used widely in the field of stealth and the study of composite film becomes the hotspot at present.Nanosized composite ferrite CoFe₂O₄/B-Co is prepared employing coprecipitation and chemical-reduction, and contrast with the prepared ferrites ferrites 94RC,NDB0408,UESTC. SEM shows that the composite ferrite is like cotton and displays one by one, their diameters are about 50nm. VSM measurement in the strong magnetic field reveals that its coercive force and remanence are zero, that is, the product is supermagnetic one. But XRD show that the other three ferrites have the same components; SEM show that ferrite 94RC is sphericity of 1μm～3μm, NDB 0408 is like flower, UESTC have flakes, sphericities and ellipsoid. The three ferrites are anisotropic from the imaginary parts of their permeability. The absorption curve shows that electromagnetic attenuation range of composit ferrite shifts to X-band (8～12GHz), the peak is 33.110dB at 10GHz. But the absorption of the three ferrites distribute mainly in the limited S-band (2～4GHz), the maximal absorption of ferrite 94RC and NDB0408 is 21.389dB and 28.125dB.The single layer films are physically mixed and prepared by polychloroprene and ferrite 94RC. One is synthesized in a lump, the maximal value of its inverse absorption is 12.88dB but the obverse is 8.54dB at 6.79GHz; the absorption band of its inverse is wider than another side. The other films are made by quartic equal steps, the absorption of its obverse and inverse have not too much differences, the peak value is 10dB at 14.4GHz.The three layer films are designed according to the impendence of ferrites, the order from bigness to smallness is 94RC>NDB0408>CoFe₂O₄/B-Co. Firstly, the polychloroprene/[graphite/NDB0408/94RC] composite film, the obverse peak attenuation is 4.43dB but 5.64dB inversely. Secondly, the polychloroprene/ (gra-phite/[NDB0408/(94RC+UEST)] composite film, the maximal absorption of its obverse and inverse are 5.78dB at 18.00GHz and 8.55dB at 17.83GHz. Finally,...