Abstract: 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.

Key words: magnetic fluid, transmission electron microscopy, chained-alignment, magnetic dipole