磁性液体纳米磁性颗粒磁场诱导链状结构研究

摘要

Chain alignment of suspended-ferroparticles in a carrier fluid exposed to the external magnetic field was investigated theoretically and experimentally.The results show that without the external magnetic field the ferroparticles were randomly distributed and when exposed to uniform magnetic field the turned out to be a chained-alignment pattern along the external magnetic field orientation at intensity of 11.1 kA/m.With the external uniform magnetic field intensity up to 28.6 kA/m,more ferroparticles closely aggregated to a chained-alignment pattern along the magnetic field direction.When the magnetic field intensity reached 28.7 kA/m in the gradient magnetic field,a large number of ferroparticles gathered around the coils and formed complex clusters,while a small number of ferroparticles demonstrated a chain-alignment pattern along r direction with weaker magnetic field intensity.When the magnetic field gradient was gradually increasing from 1.73 kA/m2 to 5.11 kA/m2,the cluster pattern of ferroparticles turned out to be dense along the axis.This research may enhance the applications of magnetic fluid in the fields of mechanical engineering,bioengineering and thermodynamic engineering.%研究了磁性液体在有、无外加磁场作用时磁性液体中纳米磁性颗粒的微观排列结构,发现无外加磁场作用时磁性颗粒随机均匀分布在载液中,有外加均匀磁场作用时,磁性颗粒沿磁场方向排列成均匀链状结构.当外加均匀磁场强度为11.1 kA/m,TEM照片清晰显示磁性颗粒排列成一条链状结构,随着外加均匀磁场强度逐渐增强到28.6 kA/m,更多磁性颗粒沿磁场方向紧密排列成链状结构.在外加梯度磁场作用下,铁芯中心处磁场强度为28.7 kA/m时,大量磁性颗粒聚集于线圈中心轴附近形成复杂链状团簇结构；沿r轴方向磁场强度较弱的地方,较少磁性颗粒排列成链状结构.当磁场梯度从1.73 kA/m2逐渐增加到5.11 kA/m2时,磁场梯度轴线上的磁性颗粒团簇结构由稀疏逐渐变成为密集.磁场诱导磁性颗粒链状排列结构的研究对磁性液体在机械工程、生物工程、热力工程等领域的应用有重要意义.