Magnetorheology of Core–Shell Structured Mesoporous Fe₃O₄@mSiO₂ Nanoparticles in Carbonyl Iron Dispersion

Abstract

Core-shell structured magnetic mesoporous Fe ₃ O ₄ @mSiO ₂ nanoparticles were successfully synthesized using a surfactant-based sol-gel approach and utilized as an additive in a carbonyl iron (CI)-based magnetorheological (MR) fluid to inhibit particle aggregation and to improve the stability and MR characteristics of the dispersion. The magnetic stimuli response of the MR fluids with and without the Fe ₃ O ₄ @mSiO ₂ additive was investigated using the controlled shear rate method, controlled shear stress method, and a dynamic oscillation test using a rotational rheometer. The dispersion characteristics of the MR fluids were measured using a Turbiscan apparatus. Compared to the pure CI-based MR fluid, the CI-based MR fluid with the Fe ₃ O ₄ @mSiO ₂ additive showed significantly higher yield stresses as well as the enhanced MR characteristics and improved dispersion stability.