Theory analyses and applications of magnetic fluids in sealing

Abstract

Magnetic fluids are the suspensions composed of magnetic nanoparticles, surfactants, and non-magnetic carrier liquids. Magnetic fluids are widely used in various fields, especially in sealing, because of their excellent features, including rapid magnetic response, flexible flow ability, tunable magneto-viscous effect, and reliable self-repairing capability. Here, we provide an in-depth, comprehensive insight into the theoretical analyses and diverse applications of magnetic fluids in sealing from three categories: static sealing, rotary sealing, and reciprocating sealing. We summarize the magnetic fluid sealing mechanisms and the development of magnetic fluid seals from 1960s to the present, particularly focusing on the recent progress of magnetic fluid seals. Although magnetic fluid sealing technology has been commercialized and industrialized, many difficulties still exist in its applications. At the end of the review, the present challenges and future prospects in the progress of magnetic fluid seals are also outlined.

Magnetic Fluids: The Interaction between the Microstructure, Macroscopic Properties, and Dynamics under Different Combinations of External Influences

“…The samples of magnetic fluid with large particles were used, in which stratification was observed for 6 h. These samples differ from the magnetic fluid used in the industry and are more stable. A collaborative effort between engineers from ‘Ferrolabs Inc.’ (Dulles, VA, USA) and a team led by Bashtovy is dedicated to studying commercial magnetic fluid [ 7 , 196 ]. In [ 7 , 196 ], they examined the processes of magnetophoresis in sealers and shock absorbers.…”

“…A collaborative effort between engineers from ‘Ferrolabs Inc.’ (Dulles, VA, USA) and a team led by Bashtovy is dedicated to studying commercial magnetic fluid [ 7 , 196 ]. In [ 7 , 196 ], they examined the processes of magnetophoresis in sealers and shock absorbers.…”

“…Magnetic fluid harbors single-domain superparamagnetic nanoparticles, typically around 10 nm in size. These early materials are considered the pioneers of 'smart' nano-dispersed materials [1,2], which are extensively explored in the scientific literature [3][4][5] and applied across various devices and technologies [6][7][8][9]. Magnetic fluid has a unique combination of fluidity and the ability to respond to an external magnetic field and has found an application in seals [7], controlled shock absorbers [6], various sensors [8], and acoustic systems [9].…”

Nanosphere Chain Model of Magnetic Fluid and Its Dynamic Performance

“…Magnetic fluids were a kind of intelligent materials that could transform from liquid to solid state under an external magnetic field, and the yield stress/viscosity could increase several times in a few milliseconds. − Due to their unique magnetorheological (MR) behavior, magnetic liquids had been widely used in the fields of polishing fluids, brakes, drug-targeted transport, and dampers. − The MR effect was greatly influenced by properties of magnetic particles, such as diameter, weight, roughness, etc. ,− However, these influencing factors were generally studied at the macroscopical level. The microstructures of magnetic fluids had a decisive effect on the macroscopic MR effect, and it was still a great challenge to investigate the mechanisms of microstructures on the MR effect of magnetic fluids.…”

Bionic Structure Inspired by Tree Frogs to Enhance Damping Performance

“…Hence, the use of additional vibration-damping devices is essential to effectively suppress these microvibrations and minimize their impact. Plenty of studies have proposed various shock absorbers to address vibration problems of spacecraft structures by using smart materials in the recent years. , Magnetic fluid (MF) is a kind of smart material, which consists of ferromagnetic nanoparticles, carrier liquid, and surfactants. − The most outstanding feature of MFs is the combination of common liquid behavior and superparamagnetic properties, which not only enables MFs to have a fast magnetic response but can also introduce magnetically controlled, flexible, and reversible flow. , Magnetic fluid shock absorbers (MFSAs) have many advantages, such as controllable damping, compact design, high sensitivity, less energy consumption and long life, and so forth. , Therefore, MFSAs are promising candidates for vibration reduction in aerospace engineering …”