Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

• Published in: Journal of magnetism and magnetic materials 2017-08, Vol.436, p.35-46
• Main Authors: Katiyar, Ajay, Dhar, Purbarun, Nandi, Tandra, Das, Sarit K.
• Format: Article
• Language: English
• Subjects: Brake presses; Colloids; Creep; Creep (materials); Damping; Elasticity; Ferrofluids; Hematite; Iron oxides; Magnetic field; Magnetic fields; Metal oxides; Nanotechnology; Nickel oxides; Physical properties; Relaxation; Stress relaxation; Temperature; Temperature effects; Viscosity; Yield strength; Yield stress
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2017.04.011

[Display omitted] •The magnetoviscous effect in ferrofluids in the presence of magnetic field is investigated.•Oxides of Fe and Ni are dispersed in oil to formulate the ferrofluids.•Drastic enhancement in the yield stress and viscosity under the magnetic field is observed for Fe3O4-based ferrofluids.•Viscoelastic properties of the formulated ferrofluids demonstrate the strong function of magnetic field.•The increase in temperature reduces the magneto-viscous effect in ferrofluids under the magnetic field. Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe3O4), Iron (III) oxide (Fe2O3) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0kPa and 2.9kPa.s, respectively for iron (II, III) oxide based colloids at 2.6vol% particle concentration and 1.2T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto-nanocolloids under magnetic fields has also been discussed. Thus, the present findings have potential applications in various fields such as electromagnetic clutch and brakes of automotive, damping, sealing, optics, nanofinishing etc.