Coating Iron Particles With SiO₂ Nanoshell

This text attempts to regard silica as shell materials,regard nanometer iron and carbonyl iron particle as core materials to prepare a kind of new-type absorbent.The structur of the core-shell particles were characterized by FTIR, TEM, SEM, XPS, XRD etc.The properties of magnetism,heat,crystalization,ectromagnetic were characterized by VSM, TG-DTA, Network Vectorial Analysis Instrument.The study on the core-shell particles shows,one extrenity of silane coupling agents at the surface of the composite particles after adding APS are connected with the Fe particles.and the other extrenity outside can polymerize with the active silica.The slick and compact surface of the composite particles shows the obvious core-shell structure.The surface of the composite particles are composed of the combined apex of the element Si,O,C,H.The element O is superfluous to the element Si. The silica coated nanometer particles after containning in N2 for 2h within 600 C is the crystallization form.thus it can sufficiently work the nano effect.The surface of the composite particles has no crystal water and no absorbing water.The anti-oxidation ability increase after coating. The saturation magnetism and the remnant magnetism of the composite particles increase while the coersive increase then decrease with the feed content of nano Fe particles increase.With the feed content of TEOS increase, the saturation magnetism and the remnant magnetism of the composite particles decrease, While the coersive changed little.The real part of the permittivity decrease with the shell of particles increase. The imaginary part decrease with the shell of particles increase at 2GHZ-10GHZ.The apex move toward the low frequency at 10GHZ-18GHZ.The TEM shows lots of nano silica particles circumfuse on the surface of the micro Fe particles after the micro Fe coated by silica.The SEM analysis shows the same result. The VSM shows the micro Fe particles have almost no remnant magnetism and coesive. The saturation magnetization decrease with the feed content of TEOSremenant magnetization and coesive are little. The XPS shows there is no combined apex of the Fe element because of the great thickness of the shell...