Preparation And Compatible Stealth Performance Of Flaky Magnetic Absorbing Materials

The morphology and composition have a significant impact on the stealth performance ofmaterials, especially for the radar and infrared compatible stealth materials. In this thesis, varioustechnologies (i.e. mechanical milling, chemical plating and solvothermal process, etc.) have beenadopted for the fabrication of series flake-like iron-based composite materials. The morphology andcrystal structure of the samples were characterized by means of X-ray diffraction (XRD), scanningelectron microscopy (SEM) and transmission electron microscopy (TEM). Vibration samplemagnetometer (VSM), Vector network analyzer (VNA) and infrared spectroscopy were adopted tomeasure the magnetic/electromagnetic parameters and radiation rate, respectively. The microwaveabsorbing property of the samples was calculated by the reflectance loss formula, meanwhile theinfrared emissivity was obtained by comparing the radiation rate.The flake-like carbonyl iron was prepared from the corresponding sphere-like iron through a ballmilling process. The maximum reflectivity loss and the minimum emissivity, which are stronglydependent on the ball size and the milling time, were measured at-35.47dB and0.77, respectively.Another kind of composite material was fabricated by combining aluminum on the surface offlake-like carbonyl iron with superior property via ball milling process. The performance of sampleswas also found to be dependent on the combination ratio and milling time. The optimal reflectivityloss and the emissivity of the sample were achieved at-13.15dB and0.05under the optimum ratioand time. Moreover, an electroless plating method was selected for the deposition of copper particleson the surface of the flake-like carbonyl iron with optimal performance. A much lower infraredemissivity was also found in as-prepared iron-copper composite materials with microwave absorbingproperty. The reflectivity loss and the emissivity of the iron-copper composite materials wererespectively tested at-19.47dB and0.50under the reaction temperature of45oC and the reactiontime of30min. Furthermore, flake-structured Fe2O3naonospheres were successfully synthesized via asolvothermal method. After coating and restoring treatment, the nano-sized flake-structured ironmaterials can be obtained. The as-prepared samples exhibit the reflectivity loss of-13.96dB as well asthe emissivity of0.20.