The Study On The Electromagnetic Characteristics Of Ferromagnetism Nanometer Particles And Surface Modification

Nanometer particles of Fe,Co, Ni, Fe-Ni, Fe-Co, Co(C), Ni(C), etc. had been obtained by DC arc plasma in 100Torr methane(CH4) gas and a 760Torr mixture of H2 and Ar atmosphere respectively. The crystal structure, microstructure, surface characterization, composition particle's size, magnetic properties, electromagnetic parameters, conductivity, etc. had been investigated by means of X-ray diffraction (XRD), transmission electron microscopy(TEM), X-photoelectron spectroscopy(XPS), gas analysis, chemical analysis, EDAX, vibrating sample magnetometer(VSM), network analyzer, surface resistivity diagonal test technique, etc.. The oxide layer on the surface of the nickel nanoparticles had been removed by dilute HC1, and subsequently modified by sodium dodecyl benzene sulfonate, Oleic acid, PAni, silane coupling agent KH550 respectively. The modify result had been investigated by means of active exponent, FT-IR, TGA-SDTA, DSC, TEM, network analyzer, surface resistivity diagonal test technique, etc..The surface layer of nanometer particles of Fe, Co, Ni, Fe-Ni, Fe-Co etc. prepared in a mixture of H2 and Ar atmosphere was metal oxide. Within the range of 2-18GHz frequency, the electric loss ability of Fe nanometer particle is superior to Co, Ni nanometer particles, because the content and electric ability of the iron oxide is larger than Co, Ni nanometer particles. The magnetic loss peaks of Fe, Ni nanometer particles appear in 10-13 GHz , 4-6GHz separately, but the nanometer particle Co has not presented the magnetic loss peak in the range of 2-18GHz frequency. Through comparing the electromagnetic parameters of several kinds of Fe-Ni alloy nanometer particles, the conclusion can be drawn that the magnetic loss frequency band can be widened by regulating the proportion of Fe, Ni elements. The electric conductivity of above-mentioned nanometer particles is poor which improves the impedance of the material so that more electromagnetic waves can be absorbed and lossed. The surface layer of nanometer particles of Co(C), Ni(C) prepared in methane(CH4) gas is carbon membrane which has improved the anti-oxidant ability of Co(C), Ni(C) nanometer particle. Co(C), Ni(C) nanometer particles have frequency response whose electric loss ability is about 25 times and 14 times of Co, Ni nanometer particles'. The magnetic loss ability of Co(C) nanometer particle is three larger times than Co nanometer particle.By comparing modification result and microwave electromagnetic parameter of modified Ni nanometer particle, the conclusion can be drawn that using 4wt. % silane coupling agent KH550 can reach the ideal modification result, make the nanometer nickel powder have better anti-oxidant ability, improve the electric loss ability and the magnetic loss ability.