MAGNETIC MATERIALS-BASED ELECTRORHEOLOGICAL FLUIDS

A type of electrorheological (ER) system, denoted the magnetic materia ls-based electrorheological fluids, is introduced. The solid particles of this system are 40-50 mu-microspheres obtained by the sol-gel proc essing of a ferroelectric material containing a ferromagnetic componen t. Since the solid material is magnetic, the presence of a small magne tic field, such as that from a small permanent magnet, can suspend the microspheres in liquid. The incorporation of a small amount of magnet ic materials thereby solves the long standing problem of particle sedi mentation in ER fluids. It is found that this type of ER fluid is very stable and exhibits a strong ER effect at low electric field. (C) 199 7 American Institute of Physics. [S0003-6951(97)01843-3].