A tensiometric study of magnetorheological suspensions' stability

Abstract

A thin (3-aminopropyl)triethoxysilane (3APTS) layer with a grafting density around 50 groups per nm 2 was coated onto soft magnetic carbonyl iron (CI) particles. Their physical characteristics were examined using various methods, and the results revealed that the coating layer did not affect the particles' morphology and magnetic properties while their resistance against thermal oxidation and chemical degradation was considerably improved. This study further evaluates the surface free energy of the particles under investigation using tensiometry, namely capillary rise experimental methods based on the Washburn theory. The dispersive and polar components of surface free energy were subsequently computed through the application of the Owens-Wendt-Rabel-Kaeble theory. It was observed that the coating of CI particles with 3APTS increased the dispersive component of surface free energy, resulting in the improved compatibility of such particles with non-polar silicone oil which is used as a carrier liquid for magnetorheological (MR) suspensions. Furthermore, the 3APTS coating has a negligible influence on MR properties in comparison with an uncoated CI particle-based MR suspension, as was proved by steady shear and small-strain oscillatory shear tests under various external magnetic fields. The improved compatibility of 3APTS-coated CI particles with silicone oil was reflected in the better sedimentation stability of the MR suspension, observed via tensiometry for the first time for MR suspensions, in comparison with the uncoated CI particle-based suspension.

A facile controllable coating of carbonyl iron particles with poly(glycidyl methacrylate): a tool for adjusting MR response and stability properties

“…An evaluation of sedimentation stability of MR suspensions via tensiometry was recently proposed by Sedlacik et al 38 MR suspensions containing 10 wt% (approx. An evaluation of sedimentation stability of MR suspensions via tensiometry was recently proposed by Sedlacik et al 38 MR suspensions containing 10 wt% (approx.…”

The enhanced magnetorheological performance of carbonyl iron suspensions using magnetic Fe3O4/ZHS hybrid composite sheets

“…10 Here, a series of peaks correspond to zinc sulphate hydroxide tetrahydrate Zn 4 SO 4 (OH) 6 $4H 2 O (ICDD-JCPDS PDF-2 entry 01-072-130500-044-0673) and zinc sulphate hydroxide pentahydrate Zn 4 SO 4 (OH) 6 $5H 2 O (ICDD-JCPDS PDF-2 entry 01-072-130500-039-0688), which indicates the presence of a mixture of both compounds. 10 Here, a series of peaks correspond to zinc sulphate hydroxide tetrahydrate Zn 4 SO 4 (OH) 6 $4H 2 O (ICDD-JCPDS PDF-2 entry 01-072-130500-044-0673) and zinc sulphate hydroxide pentahydrate Zn 4 SO 4 (OH) 6 $5H 2 O (ICDD-JCPDS PDF-2 entry 01-072-130500-039-0688), which indicates the presence of a mixture of both compounds.…”

“…[1][2][3] Such suspensions are usually composed of micron-sized ferromagnetic 4-6 particles with high saturation magnetization dispersed in a nonmagnetic carrier liquid. [9][10][11][12][13][14] Therefore, due to their extraordinary properties, MR suspensions have recently begun to be utilized in many industrial applications. 7,8 Generally, in the absence of an external magnetic eld, the particles are randomly dispersed in the carrier liquid and the suspensions exhibit a Newtonian-like behaviour.…”

The Synthesis of Organic Oils Blended Magnetorheological Fluids with the Field-Dependent Material Characterization

“…The results showed that the presence of guar gum enhances the thixotropy and sedimentation stability effectively. Sedlacik et al [7] employed the method of coating a thin layer of 3APTS with a grafting density of 50 groups/nm 2 , and identified improved compatibility of non-polar silicone oil with coated particles. Kumar [8] studied the characterization of honey oil-based MR fluid for the brake applications, whereas the degradation and stability of the fluid were not critically identified.…”