Nanosized Fe3O4 Particles Research Articles

Electrodeposition and corrosion behavior of Zn–Ni and Zn–Ni–Fe2O3 coatings

A thin film of Zn–Ni–Fe2O3 on steel substrates was prepared by electrodeposition technique using Zn–Ni alloy plating solution with nano-sized Fe2O3 particles. The cathodic polarization and cyclic voltammetry techniques were used to explain deposition process. The corrosion behavior of deposits was evaluated by polarization and impedance studies. Scanning electron microscope (SEM) images were used to study the surface morphology of coating. The grain size and amount of Fe2O3 particles present in composite coating were measured by X-ray diffraction pattern (XRD) and energy dispersive X-ray diffraction spectrometer (EDS), respectively.

Enhancement of Reduction Rate of Iron Ore by Utilizing Iron Ore/Carbon Composite Consisting of Fine Iron Ore Particles and Highly Thermoplastic Carbon Material

Decreasing the thermal reserve zone temperature is believed to increase the energy efficiency of blast furnace iron-making. To do so, either the direct reduction reaction rate or the coke gasification reaction rate must be significantly increased below 1000°C in CO-lean atmosphere. An iron ore/carbon composite (IOC) has been proposed as a new raw material that can enhance the reduction rate of iron ore. In this paper the possibility of the reduction rate enhancement was examined by preparing a kind of ideal IOC sample consisting of nano-sized Fe2O3 particles (10–70 nm in diameter) and a carbon material prepared from a thermoplastic resin. The nano-sized Fe2O3 particles in the IOC sample were surprisingly reduced to Fe in a few minutes at as low as 650°C in an inert atmosphere. This was realized by increasing the interfacial area between the Fe2O3 particles and carbon and by establishing intimate contact between the two. The carbon in the IOC sample was also completely gasified in less than 10 minutes at as low as 750°C in a CO2 atmosphere. The dramatic enhancement of the gasification rate was found to be realized by the enhancement of one of the direct reduction reactions, the reaction between Fe3O4 particles and carbon, by the aid of in-situ XRD measurement. This suggested that the enhancement of both the reduction reaction rate and the gasification reaction rate is realized by the same mechanism. These new findings will give a clue for designing IOC samples applicable to the blast furnace iron-making.

Microwave Absorption Behavior of ZnO Whisker Modified by Nanosized Fe<SUB>3</SUB>O<SUB>4</SUB> Particles

Tetra-needle-like ZnO whisker was magnetic modified through in situ synthesis of nanosized Fe3O4 particles on the surface of the whisker, and the microwave absorption behavior of the as-prepared product was investigated in detail. The result of the comparative microwave absorbing experiment showed that the magnetic modified ZnO whisker appeared more superior property of microwave absorption than that of the original ZnO whisker in 2-18 GHz. Further investigation indicated that the microwave absorption behavior of the product was influenced by ferrite content and Fe3O4 particles' distribution in the product. When the ferrite content of the product changed from 2 wt% to 9 wt%, the microwave absorbing ability of the product was increased; then, the microwave absorbing ability of the product decreased with the further increasing of ferrite content from 9 wt% to 16 wt%. The product with uniform distribution of Fe3O4 particles showed better microwave absorption property than that with irregular distribution of Fe3O4 particles, and this result inferred that the biphase interface between ZnO and Fe3O4 contributed to microwave absorption through interface polarization.

The Influence of Synthesis Parameters on FeO(OH) / Fe2O3 Formation by Hydrothermal Techniques

In this paper, a hydrothermal method of high-pressure and low-temperature synthesis conditions is presented as a simple single-step technique to obtain crystalline nanoparticles of iron oxides. The aim of this work has been to demonstrate the influence of the main synthesis parameters on the formation of nanosized Fe2O3 particles using statistical methods and to establish the most significant effects. Based on mathematical pre-modeling calculations, the best reaction conditions for the hydrothermal process have been chosen, and controlled crystalline nanostructures of iron oxides could be prepared

Preparation and characterization of TiO2-masked Fe3O4 nano particles for enhancing catalytic combustion of 1,2-dichlorobenzene and incineration of polymer wastes

Nano-sized Fe3O4 particles that were covered with a porous layer of nano-sized TiO2 (TiO2-masked Fe3O4) were prepared by simply controlling pH of aqueous slurry solution containing the two particles that have different values of isoelectric point (IEP coating method). The prepared sample showed an effective masking of red-brown color of Fe3O4 particles into a pale yellow. XPS and TEM measurements confirmed an effective covering of TiO2 particles to the Fe3O4 surface. XANES analyses revealed the transformation of some Fe2+ ions into Fe3+ in the Fe3O4 structure (formation of Fe3O4+δ) due to a close interaction between Fe3O4 and TiO2 during the IEP coating, which was not observed in physical mixture of dry powders of Fe3O4 and TiO2. Compared with pure Fe3O4 or the physical mixture, TiO2-masked Fe3O4 particles exhibited an activity enhancement for both catalytic oxidation of 1,2-dichloro benzene and thermal incineration of catalyst-embedded polyethylene and polystyrene. Temperature-programmed reduction of CO and temperature-programmed surface reaction of CO with O2 revealed that oxygen vacancy sites on Fe3O4+δ played roles for the adsorption and reaction of CO, and close TiO2 provided oxygen to the Fe3O4+δ sites. Compared with pure Fe3O4 particles, TiO2-masked Fe3O4 particles also provided a good color-masking effect when embedded in polymers and improved the thermal stability of base polymers for high temperature fabrication.

Adsorption of Sodium Oleate on Nano-sized Fe3O4 Particles Prepared by Coprecipitation

Nano-sized Fe3O4 is one of the most important magnetic materials wildly applied in various fields and sodium oleate (SO) is a very useful anionic surfactant for dispersing nano-particles in aqueous solution in the practical applications of nano-particles. However, studies of its adsorption properties on Fe3O4 nano-particles are scarce. This work firstly characterized the shape, size and phase structure of the nano-sized magnetite (Fe3O4) particles synthesized with chemical co-precipitation in aqueous solution by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Then, the UV absorbance behaviors of sodium oleate (SO) aqueous solution were explored and the adsorption of SO on nano-sized Fe3O4 particles was carried out. Based on the UV characteristics of SO, the isothermal adsorption of SO on these magnetite nanoparticles was measured under pH 10.5 at room temperature. Meanwhile, Fourier-transform infrared spectroscopy (FT-IR) was used to confirm the attachment of SO on the magnetic particles. Moreover, the adsorption equilibrium isotherm was fitted well by the Langmuir mode and proved that this adsorption was a monolayer adsorption. Keywords: Fe3O4 nanoparticles, Sodium oleate, Absorption, Adsorption, UV Spectrophotometry

Iron oxide nanoparticles stabilized inside highly ordered mesoporous silica

Nanosized iron oxide, a moderately large band-gap semiconductor and an essential component of optoelectrical and magnetic devices, has been prepared successfully inside the restricted internal pores of mesoporous silica material throughin-situ reduction during impregnation. The samples were characterized by powder XRD, TEM, SEM/EDS, N2 adsorption, FT-IR and UV-visible spectroscopies. Characterization data indicated well-dispersed isolated nanoclusters of (Fe2O3)n, within the internal surface of 2D-hexagonal mesoporous silica structure. No occluded Fe/Fe2O3 crystallites were observed at the external surface of the mesoporous silica nanocomposites. Inorganic mesoporous host, such as hydrophilic silica in the pore walls, directs a physical constraint necessary to prevent the creation of large Fe2O3 agglomerates and enables the formation of nanosized Fe2O3 particles inside the mesopore

Incrusting structure of nanosized Fe3O4 particles in magnetic fluids

High-performance nanosized Fe3O4 magnetic fluids are prepared by chemical co-precipitate method. The microstructure of magnetic fluids is characterized using a transmission electron microscope (TEM) and high-resolution microscope (HREM). The results are satisfactory. The nanosized magnetic particles have diameter of 8–10 nm and the minimum diameter is 4 nm, belonging to super-paramagnetic material. The nanosized magnetic particles crystallized completely and have clear crystal boundary. The surfactant used in the test coats the magnetic particles homogeneously and forms a uniform and complete elastic spherical shell of amorphous phase around the magnetic particles. The study proves that the incrusting layer of surfactant has the protective effect and stable effect on the magnetic particles. These effects can enhance and maintain the magnetic properties of the magnetic fluids effectively.

Homogeneous coatings of nanosized Fe2O3 particles on Y2O2S:Eu

The red emitting phosphor Y2O2S:Eu commonly applied in colour television tubes was pigmented with a thin homogeneous layer of nanosized Fe2O3 particles based on a novel coating strategy. In a first step the phosphor was covered with nanosized Fe3O4 particles which themselves were prepared by reduction of an Fe(III)-salt with hydrazine. Thereafter, Fe3O4 was converted to Fe2O3 by heating to 450°C in air. Surface composition and body colour of the corresponding phosphor samples were investigated applying ESCA and measuring diffuse reflectance. The size of the Fe2O3 particles as well as the homogeneity of the resulting coating were studied by SEM. Furthermore, the adhesion of Fe2O3 particles on the phosphor surface was examined.