Preparation and characterization of magnetite ferrofluid for generating current induced

In this research, morphology, average particle size and magnetic properties of magnetite (Fe3O4) particles were studied and mixed with a carrier liquid to obtain a ferrofluid. Further, an attempt to use the ferrofluid to generate induced electric current was to be carried out. Magnetite (Fe3O4) nanoparticles were prepared by wet milling using mechanical alloying in a hardened steel vial using a SPEX8000D mill with different milling times of 10 hours, 20 hours, 30 hours and 40 hours to obtain magnetite nanoparticles in bigger quantities compared with other method. Firstly, micron-size magnetite was milled with water using different milling times of 10 hours, 20 hours, 30 hours and 40 hours. After that, the powder was dried for a day. The material was crushed with mortar and pestle and sieved to obtain a fine powder. Next, the magnetite milled with oleic acid with different times of 10 hours, 20 hours, 30 hours and 40 hours. After that, the powder was washed with hexane mixed with ethanol. Finally the powder must be dried for a day. For the next sample, the sample was milled with water and mixed with hydrochloric acid, HCl, diluted with 100 ml water in a beaker at 70oC. Besides, 0.1ml oleic acid as surfactant was mixed with 10 ml acetone and a cosurfactant in another beaker. This solution had to be put slowly into a beaker contains magnetite and was slowly stirred. Then, 10 ml ammonia solution was put into this beaker to give a colloidal suspension. The top layer of this suspension was centrifuged by using methanol mixed with acetone. This wet powder mass was then extracted and dried for 3 hours. The magnetic nanoparticles were analyzed by XRD, TEM, FTIR and VSM analysis. The result showed that superparamagnetic magnetite nanoparticles were obtained, suggesting that the top–layer suspension was suitable to be used as ferrofluid particles. The phase of magnetite was confirmed by X-ray diffraction (XRD) using a Philips X-ray diffractometer. The average particle size of magnetite was studied using a Transmission Electron Microscope (TEM). The magnetic properties studies were carried out by using a Vibrating Sample Magnetometer (VSM). The XRD patterns showed an improvement of crystallinity with increasing milling time. The XRD patterns also showed the all samples as magnetite nanoparticle and no impurities coming from this sample. FTIR analysis showed peaks of pure magnetite and oleic acid. Hysteresis analysis from VSM shows that when milling time increased, the saturation magnetization increased but the coercivity decreased parallel with average particle size decrease. TEM micrographs show that with increase milling time, average particle size becomes decreased. The magnetite nanoparticles from the 40 hours milling time were mixed with silicon oil to yield a ferrofluid. This ferrofluid was used to generate induced current by passing it in a plastic tube through a magnetic field. The experiment on induced current showed that the induced current generally increased when the weight of magnetite increased.

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