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Precursors with NiCO3·2Ni(OH)2·2H2O- and Fe2O3·nH2O-coated alumina, graphite and cenosphere were synthesized by precipitation using ferrous sulfate, nickel sulfate, ammonium bicarbonate, alumina, graphite and cenosphere as the main starting materials. Magnetic γ-FeNi-coated alumina, graphite and cenosphere core–shell structural microspheres were subsequently prepared by thermal reduction of the as-prepared precursors at 600 °C for 2 h. Precipitation parameters, e.g. concentration of ceramic micropowders (10 g/L), sulfate solution (0.2 mol/L), rate of adding reactants (3 mL/min) and pH value were optimized by a trial-and-error method. Powders of the precursors and the resulting coating of γ-FeNi with grain size below 40 nm on alumina, graphite and cenosphere microspheres were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The magnetic properties of the nanosize γ-FeNi-coated alumina, graphite and cenosphere microspheres were measured by vibrating sample magnetometer (VSM). The results show that the core–shell structural γ-FeNi-coated ceramic microspheres exhibited higher coercivity than pure γ-FeNi powders, indicating that these materials can be used for high-performance functional materials and devices.  相似文献   
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The cathodic behavior of graphite in KF-AlF3-based melt with various cryolite ratios (CR; molar ratio of KF to AlF3) were investigated by means of cyclic voltammetry, sampled-current voltammetry, and chronopotentiometry. The limiting current of aluminum deposition and critical current density of potassium intercalation on graphite cathode in KF-AlF3-based melt decreased with the increase of CR of the melt. Lowering the CR of KF-AlF3-based melt suppressed the potassium intercalation but enhanced the formation of aluminum carbide. In the KF-AlF3-based melt with CR of 1.0, formation of Al4C3 seriously occurred, which resulted not only from the chemical reaction of aluminum and carbon but also from the electrochemical reduction of carbon under higher overpotential. However, both the X-ray diffraction and scanning electron microscopy failed to detect the existence of potassium–graphite intercalation compound and Al4C3 in the resultants after galvanostatic electrolysis.  相似文献   
3.
Ni coated cenosphere composites are successfully fabricated by heterogeneous precipitation method using metal salts, ammonium hydro-carbonate and cenospheres as the raw materials. The cenosphere particles are characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) during and after the coating process. All results show that relatively uniform, smooth and compact Ni layer has been successfully coated onto cenospheres under the given conditions, furthermore, the nanometer Ni crystallite has a face-centered cubic structure. Magnetic property of Ni coated cenosphere composites can be adjusted by controlling the synthesis conditions and content of magnetic metal. The low density Ni coated cenosphere composites may be utilized for electromagnetic wave shielding and microwave absorbing materials.  相似文献   
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采用电化学沉积Ag的方法对多孔硅表面进行钝化改善其发光性能,探讨了沉积电流密度大小与沉积Ag的形式以及多孔硅表面亲水性处理对沉积Ag均匀性的影响. 结果表明,改变沉积电流密度大小后出现了两个临界电流密度,即不发生Ag沉积和在PS表层形成Ag电镀,深入PS孔道内沉积Ag的电流密度范围为50~400 A/cm2;多孔硅表面亲水性处理对沉积Ag均匀性有积极作用,在相同的实验条件下,未经表面亲水性处理的疏水多孔硅表面沉积Ag不均匀,而经过SC-1溶液处理后的亲水多孔硅表面上沉积Ag分布较均匀. 进一步研究了均匀沉积Ag钝化处理对PS的光致发光强度和稳定性的影响,证明采用Ag钝化处理能有效地抑制发光强度的衰减;而过量的Ag沉积会使PS发生荧光猝灭现象.  相似文献   
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