Development and micro-gap flow evaluation of electro-rheological nano-suspensions

Simultaneous observations of microgap flow behavior and microstructure of electro-rheological nano-suspensions based on titanium dioxide nano-particles

“…It is noteworthy that concentric rings of particles were observed along the shear flow for the nano-suspension under shear and electric fields [24,25], the ring-like microstructure of which was similar to that observed for micro-suspensions in a fixture of parallel disks [10]. From simultaneous observations of the flow behavior with rheology, it was also found that the ringlike microstructure was closely related to larger responses of the ER effect, whereas the flow behavior was not stable very much during the longer shearing time, especially at higher shear rates [24][25][26][27].…”

“…The effects of particle diameter on the order of 100 nm [26] and continuous phase of suspending oil [27] were also discussed for nano-suspensions with ϕ of 8.8 vol %. At the same time, the effect of shearing time for stability was evaluated [26,27].…”

“…Therefore, particular attention has been directed toward the ER nano-suspension based on nano-particles [22,23]. In previous papers [24][25][26][27], ER nano-suspensions based on titanium dioxide (TiO 2 ) nano-particles have been reported. The ER effect was observed within a narrow gap between electrodes of 50 μm for a suspension composed of rutile TiO 2 nano-particles with diameter of primary particles around 15 nm and a silicone oil (of linear molecules) with a viscosity η c of 0.05 Pa·s, the particle volume fraction ϕ of which was 8.8 vol % [22].…”

“…At the same time, the effect of shearing time for stability was evaluated [26,27]. For a nano-suspension based on anatase TiO 2 nano-particles with diameter around 300 nm and a chemically modified silicone oil (of branched molecules) with η c of 0.1 Pa·s [27], a plateau stress in the absence of the applied electric field around 1 or 2 Pa was much lower than that based on the silicone oil of 0.05 Pa·s, the results of which were closely related to the size of microstructures (or secondary particles) developed in the nano-suspensions.…”

“…At the same time, the effect of shearing time for stability was evaluated [26,27]. For a nano-suspension based on anatase TiO 2 nano-particles with diameter around 300 nm and a chemically modified silicone oil (of branched molecules) with η c of 0.1 Pa·s [27], a plateau stress in the absence of the applied electric field around 1 or 2 Pa was much lower than that based on the silicone oil of 0.05 Pa·s, the results of which were closely related to the size of microstructures (or secondary particles) developed in the nano-suspensions. On the other hand, the ER response measured at a given strength of the electric field for the nano-suspension based on the chemically modified silicone oil was effectively induced by the electric field, especially with low strengths, and it was larger than (or comparable to) that of the nano-suspension based on the silicone oil [27].…”