A review of the fabrication of enhanced-performance magnetorheological fluids using carbonyl iron powder

Magnetorheological fluids (MRFs) are a type of smart fluid whose mechanical properties, such as viscosity, can be controlled through an external magnetic field. They are dispersions comprising magnetic materials, a carrier fluid, and additives. Carbonyl iron powder (CIP), a type of pure iron powder with unique morphological properties, is commonly used due to its low hysteresis, ease of manufacturing, low cost, and high saturation magnetization. When exposed to a magnetic field, MRFs can rapidly transition from a liquid to a solid-like state within milliseconds. They are utilized in various industries, including construction, automotive, and aerospace, due to their adjustable physical properties. However, limitations such as a low magnetorheological effect and instability hinder their wider industrial application. This study aims to review and discuss the characteristics of MRFs, mainly focusing on the impacts of morphological variations in CIP, the presence or absence of surface treatments, and the incorporation of different additives, with an emphasis on magnetorheological and sedimentation properties.