核壳结构石墨/磁性纳米合金复合微球的制备

Fabrication of Core-Shell Microspheres of Graphite/Magnetic Nanocrystalline Alloy Composite

以硫酸亚铁、硝酸钴、硫酸镍、碳酸钠和石墨微球为主要原料,利用非均相沉淀工艺分别制备出水合氧化铁、碱式碳酸钴和碱式碳酸镍包裹石墨微球的前驱体复合微球;然后将前驱体复合微球于600℃热还原处理2 h,分别得到了钴铁、铁镍和钴镍磁性纳米合金颗粒层均匀包裹石墨微球的粉体材料。利用SEM,EDS,XRD对前驱体复合微球和核壳结构石墨/磁性纳米合金复合微球的形貌、成分、物相进行了表征,利用VSM对核壳结构石墨/磁性纳米合金复合微球的磁性能进行了研究。这些核壳结构复合微球的磁性合金颗粒层分别由晶粒为37.9 nm的Co_(0.5) Fe_(0.5)、38.5 nm的Fe_(0.5)Ni_(0.5)和38.2 nm的Co_(0.5)Ni_(0.5)组成,相应的矫顽力分别为36676,20972,16894A/m。

Amorphous graphite microspheres were coated by Fe2O3·nH2O-, Co2（OH）2CO3- and NiCO3·2Ni（OH）2·2H2O via the aqueous heterogeneous precipitation of ferrous （Ⅱ） sulfate, cobalt nitrate, nickel sulfate, sodium carbonate and spherical graphite. The magnetic nanocrystalline CoFe-, FeNi- and CoNi were formed on the graphite microspheres by the subsequent hydrogen reduction of the precursors coated on the microspheres at 600 ℃ for 2 h. The morphology, composition, the precursors and the resultant core-shell structural graphite/ magnetic nanocrystalline microspheres were characterized by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. The magnetic properties of the graphite/magnetic nanocrystallines were studied by vibrating sample magnetometer （VSM）. The coatings on graphite consist of 37.9 nm Co0.5Fe0.5, 38.5 nm Fe0.5Ni0.5 and 38.2 nm Co0.5Ni0.5, with their corresponding coercivity value of 36676, 20972, and 16894 A/m, respectively.