中文摘要：

以硅酸钠为主要原料，通过液相沉淀法在纳米镍粉表面包覆了一层SiO2。应用XRD、FTIR、TEM、TGA、DSC和VSM对复合粉体的结构、形貌和磁性能进行了研究。结果表明，SiO2以非晶态的形式包覆在纳米镍粒子表面，形成了核一壳结构，降低了纳米粉体的团聚现象。TGA和DSC结果表明，SiO2的包覆提高了纳米粉体的抗氧化性。磁性分析结果表明，粉体包覆前由于表面氧化层（NiO）的存在，粉体的磁滞回线偏移；包覆后的粉体由于SiO2的存在，饱和磁化强度降低，矫顽力升高。

英文摘要：

Magnetic Ni nanoparticles coated with silica were successfully synthesized via the liquid deposition method using Na2SiO3 as the main raw material, and their structures and properties were studied by X-ray diffraction （XRD）, Fourier transform infrared spectrometer （FTIR）, transmission electron microscopy （TEM）, thermogravi- metric analysis （TGA）, differential scanning calorimetry （DSC） and vibrating sample magnetometer （VSM）. XRD, FTIR and TEM results show that there is noncrystal silica on the surface of Ni nanoparticles and it prevents the nano- particles from agglomerating. The oxidation resistance of SiO2/Ni nanoparticles is improved because of the protection of the silica coating. Magnetic properties show that Ni and SiO2/Ni are ferromagnetic materials. The hysteresis loop of Ni has an excursion because of the anti-ferromagnetic NiO. The silica coating reduces the saturation magnetization and improves the coercivity.