EFFECT OF STATIC MAGNETIC FIELD ON THE MORPHOLOGY AND Si CONTENT OF Fe-Si COMPOSITE COATING

The Si particles with average size of 2 mu m were dispersed in plating solution, and the electrodeposition process of Fe-Si composite coating under a static magnetic field was studied. The influences of orientation, flux density of magnetic field (MFD) and current density on the morphology and Si content of Fe-Si composite coatings were discussed. It was found that the Si content of coatings for vertical electrodes increased significantly with increasing the MFD in both parallel and perpendicular magnetic field (regard to current) with the MFD ranging from 0 T to 1 T. In the case of aclinic electrodes, the Si content of coating can reach 37.94% (mass fraction) without magnetic field. However, after applying a perpendicular magnetic field, the Si content of coatings decreased sharply with increasing the MFD (only 2.83% at 1 T). Meanwhile, many striated iron matrix protuberances with Si particles appeared perpendicular to the direction of magnetic field on the coatings surface.. Moreover, the Si content of coatings decreased with increasing current density for both aclinic and vertical electrodes in 1 T perpendicular magnetic field, while that for vertical electrodes first increased and then decreased and reached maximum value at about 20 mA/cm(2) in 1 T parallel magnetic field. Theoretical analysis shows that the change of morphology and Si content of coatings were mainly attributed to the formations of macroscopic magnetohydrodynamics (MHD) and micro-zone MHD effect caused by Lorenz force.