Thermal stability, rheological and morpho-structural properties of the magnetorheological fluid MRF122 employed in spherical joint mechanisms.

Autor: Sârbu, Daniela, Bîzdoacă, Nicu George, Cioateră, Nicoleta, Vladu, Cristian Ionel, Rotaru, Andrei, Pană, Cristina Floriana, Pătraşcu, Daniela Maria, Florian, Gabriel, Rotaru, Petre
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Zdroj: Journal of Thermal Analysis & Calorimetry; Feb2023, Vol. 148 Issue 4, p1289-1308, 20p
Abstrakt: A magnetorheological fluid hybrid material (MRF122) was investigated for determining the thermal stability, rheological and morphological properties, in order to employ further these properties to design a spherical joint system that uses this fluid. To improve the rheological properties of the magnetorheological fluid, an energization program was applied, by introducing it into a magnetic field with a magnetic induction of 0.37 T, for 5 days. The thermal analysis established that MRF122 and the energized-MRF122 are stable up to 175 °C, above this temperature continuing with an oxidative decomposition of the liquid hydrocarbon mixture in which the ferromagnetic microcrystals are suspended; six exothermic stages of oxidation and structural transitions of iron and of its oxides follow. At over 900 °C, magnetite (majority) and siderite phases are formed. Rheological measurements show that the viscosity of both samples decreases with increasing shear rate, and throughout the shear rate range, the viscosity of the energized MRF122 sample is lower than that of the MRF122 sample. When the magnetic field is applied for the energization, the agglomerations of ferromagnetic nanoparticles in MRF122 probably disperse. Both fluid samples have non-Newtonian pseudo-plastic behaviour (viscosity decreases with increasing shear rate). By determining the storage modulus and the loss modulus as a function of the increasing angular frequency, the elastic properties of MRF122 decrease, while the plastic properties increase (as well as the tangent of the loss factor). [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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