Single-walled carbon nanotube added carbonyl iron suspension and its magnetorheology

Single-walled carbon nanotube (SWNT) was introduced to the carbonyl iron (CI) based magnetorheological (MR) fluid to improve its sedimentation problem. SEM images indicated that the submicron-sized SWNT filled the interspaces among CI particles, consequently preventing serious sedimentation problem, so sustained the stability of the MR fluid. The MR characteristics showed that shear stress of the CI/SWNT system was similar to that of the pristine CI under a magnetic field, but became lower than that without a magnetic field which corresponded to a lower shear viscosity, suggesting much improved uniform dispersion by adding small amount of SWNT. It was also found that the sedimentation rate of the CI/SWNT suspension was noticeably reduced, without considerably affecting the yield behavior of the MR fluid. (c) 2006 Elsevier B.V. All rights reserved.