Field-dependent characteristics of magnetorheological fluids containing corroded iron particles

Abstract

Magnetorheological (MR) devices in vehicle applications and robotic systems require both consistent control performance and reliable operation. However, corrosion of iron particles in MR fluid may occur during long-time operation. This corrosion behavior can significantly affect the performance and reliability of application devices or systems utilizing MR fluids. This study experimentally investigates the effect of the MR particle corrosion on the performance of MR fluids in terms of the field-dependent yield stress magnitude and shear stress controllability. MR particles are first corroded by two different liquids; water–sodium chloride solution and water–calcium chloride solution. The resulting MR particles are examined by scanning electron microscopy and their molar ratios are analyzed by energy dispersive x-ray analysis. Using the corroded MR particles, MR fluid is synthesized for evaluation of the effects on its characteristics. A rotational viscometer is used to measure the field-dependent shear stress and response time. The measured results are compared between the original MR fluid composed of the non-corroded iron particles and the MR fluid composed of the corroded iron particles. In addition, the effect of the corroded particles in MR fluid on the shear stress controllability is investigated in the time domain.