With the copper/iron cinder as the starting material,ferrous ions were obtained through maturing,acid leaching,reducing and purifying processes,and then iron nanoparticles were prepared by reacting with sodium borohydride in the system of ethanol-water.The nano Fe/SiO2 core-shell composite particles were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS).The products were characterized by X-ray diffraction (XRD),transmission electron microscope (TEM) and reflectance absorption infrared spectroscopy (RA-IR).The particles were randomly dispersed in paraffin at a mass ratio of 5.5∶4.5 for microwave electromagnetic parameters detection in the frequency range of 2.0—18.0 GHz by vector network analyzer.The results showed that there were two characteristic absorption peaks of Si—O and Si—O—Fe bond appearing at 1389 cm-1 and 878 cm-1,which indicated that the nano iron was successfully coated by SiO2.Through measuring and calculation,the minimal reflection loss was-39.0 dB at 17.2 GHz when the sample thickness was 4.5 mm.So nano Fe/SiO2 core-shell composite particles can be prepared from copper/iron cider to be used as an effective microwave absorbing material.
