【作者】 张锋；

【导师】 丁明； 韩效钊；

【作者基本信息】 合肥工业大学 ， 化学工艺， 2005， 硕士

【摘要】 本论文研究了化学共沉淀法制备ZnxFe3-xO4(x=0. 1～0. 5) 纳米粉体过程中,反应温度、反应时间和铁盐浓度对ZnxFe3-xO4纳米粉体粒径的影响,得出了制备锌铁氧体粉体的最佳条件,并制备了一系列的ZnxFe3-xO4(x=0. 1～0. 3) 纳米粉体,测量、分析了他们比饱和磁化强度。采用改进的化学共沉淀法制备了分散性能更好的锌铁氧体粉体,进而合成了一系列浓度磁性液体,研究了它们的性能。利用我们自己制备的磁性液体,设计了搅拌轴密封装置。另外,根据改进的工艺,设计了工业化生产磁性液体的工艺和设备。结果表明:在化学共沉淀反应中,对ZnxFe3-xO4纳米粉体的形成和粒径影响因素最大的是反应温度,其次是反应时间和铁盐浓度。反应温度为60℃,晶化时间为4min,铁盐浓度为1mol/L时,可以得到平均粒径为8nm的尖晶石型的ZnxFe3-xO4粉体材料。在ZnxFe3-xO4纳米粉体中,随着Zn2+的含量的增大,ZnxFe3-xO4粉体的比饱和磁化强度(σs)增大,当Zn2+的含量在0. 2时,σs达到最大,为63. 07Am2/kg,此后再增加Zn2+的含量,σs反而下降。油酸在粉体制备过程中的协同改性过程为羧酸基团与ZnxFe3-xO4晶核表面的羟基发生缩合反应,从而在其表面生成了一层包裹层,既控制了晶核的长大,又减少了生成的粉体间的团聚。油酸改性后的ZnxFe3-xO4粉体,粒径在6-8nm,粒径分布更加均匀,分散性非常好。磁性液体在外磁场的作用下表现出超顺磁性,其饱和磁化强度随密度的增大而增大,成直线关系,最大可达29. 93 Am2/kg。更多还原

【Abstract】 The effect of the technological parameters such as the reacting temperature, the reacting time and the concentration of reactant on the formation and the particle size of Zn_xFe_3-xO₄（x=0.1-0.5） nanopowders, which are prepared by chemical coprecipitation method, has been explored. The best reacting condition was found, then a series of Zn_xFe_3-xO₄（x=0.1-0.3） nanopowders were made, their specific saturation magnetization were measured and analysed. Using modified chemical coprecipitation method, the more dispered Zno.2Fe2.gO4 nanopowder was prepared, then using this nanopowder, a series of magnetic fluids were prepared. A magnetic fluid rotary shaft seal mechanism was designed. In addition, according to our modified technology, the method and facility to prodce magnetic fluid were designed.The results show that the particle sizes are about 8 nm and the crystal structure is spinel, when the reacting temperature is 60℃,the reacting time is 4 minute and the reactant concentration is 1 mol / L. In Zn_xFe_3-xO₄ nanoparticles, at first the specific saturation magnetization（σ_s） increase with the increase of content of Zn²⁺（x）, when x is 0.2, σ_s is biggest, which is 63.07Am²/kg, thenσ_s is decrease with the increase of x.Using modified chemical coprecipitation method and using oleic acid as surfactants, not only the agglomeration problem can be solved, at the same time, the Zn_xFe_3-xO₄ nanoparticles, whose particle diameter is at 6-8nm, can be prepared. The magnetic fluids show superparamagnetic in the applied magnetic field and the specific saturation magnetization increase with the density, the utmost value is up to 29.93 Am²/kg.更多还原