Search results for "Ferrites"
showing 7 items of 7 documents
Valorisation of industrial iron oxide waste to produce magnetic barium hexaferrite
2016
Barium M-type hexagonal ferrite (BaM, BaFe12O19) is an immensely important magnetic material, which we have successfully made from the simple valorisation of Fe-rich industrial waste from steel wire drawing, with addition of BaCO3 and heating in air to 1000 degrees C. The optimum ratio of Fe. Ba (producing 86 wt% BaM) was found to be 11: 1 (non-stoichiometric), and secondary phases of alpha-Fe2O3 (non-magnetic) and ZnFe2O4 (poorly antiferromagnetic) were always present. This material consisted of small submicron platelets. A hard magnetic ferrite was produced with Ms=48.6 A m(2) kg(-1) and H-c=211.5 kA m(-1). The highest density was achieved by sintering samples with Fe: Ba ratios of 11: 1 …
Assessment of the Current for a Non-Linear Power Inductor Including Temperature in DC-DC Converters
2023
A method for estimating the current flowing through a non-linear power inductor operating in a DC/DC converter is proposed. The knowledge of such current, that cannot be calculated in closed form as for the linear inductor, is crucial for the design of the converter. The proposed method is based on a third-order polynomial model of the inductor, already developed by the authors; it is exploited to solve the differential equation of the inductor and to implement a flux model in a circuit simulator. The method allows the estimation of the current up to saturation, intended as the point at which the differential inductance is reduced to half of its maximum value. The current profile depends al…
Spark plasma sintering of cobalt ferrite nanopowders prepared by coprecipitation and hydrothermal synthesis.
2007
International audience; Cobalt ferrite exhibits a high coercivity at room temperature and a strong magnetic anisotropy compared to the other spinel ferrites and, consequently appears as an interesting material for permanent magnets and high-density recording. The magnetic properties depend also on the crystallite size. In order to keep the powder properties in a bulk material, dense nanostructured cobalt ferrite has to be sintered. A field activated sintering process like spark plasma sintering (SPS) may be promising for such challenge. The present paper deals with: (i) the preparation of cobalt ferrite by two methods: coprecipitation and hydrothermal synthesis in supercritical water; (ii) …
Flash microwave synthesis of trevorite nanoparticles.
2008
Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named 'lithium-ion' batteries. In this study, NiFe{sub 2}O{sub 4} was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe{sub 2}O{sub 4} nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m…
Photoelectrochemical properties of doped lanthanum orthoferrites
2013
Abstract LaFeO 3 powders doped with Sr (20 mol%) and Cu (0-10-20 mol%) were prepared by citrate auto-combustion synthesis and investigated in terms of crystal structure, morphology, surface area and optical properties. All powders showed photocurrent response in the form of a pasted and annealed electrode and as slurry electrode; the highest value was obtained for undoped orthoferrite calcined at 600 °C. Their physical–chemical properties were related to photoelectrochemical behaviour. The position of the quasi-Fermi level of electrons for all the photocatalysts calcined in the range 600–980 °C is about the same within experimental error (between −0.62 and −0.67 V with respect to Ag/AgCl re…
A Ferrite Tubular Linear Motor (FTLM): Analysis and design
2015
The electromagnetic linear machines have wide applications in the electromagnetic aircraft launch systems [1] and in transportation systems [2]. Additional energy saving and efficiency can be achieved using a linear motor in the refrigeration application [3]. Linear electromagnetic machines are also very suitable for high-speed packaging, manufacturing sectors and precision positioning. There are different linear motor topologies. Tubular permanent-magnets are particularly attractive since they have a high thrust force density and high efficiency, no end windings, and zero net attractive force between stator and armature. There are various tubular motor topologies, in which the armature may…
The role of the effect of manufacturing tolerances on a tubular linear ferrite motor
2015
Electric machines are often designed without considering workmanship and materials tolerances. Their manufacturing process involves a series of steps, starting with raw materials and ending with the machine assembly. In each of these steps occur deviations due, for instance, to mistakes in positioning tools or to the tolerances in the electrical and magnetic characteristics of the materials. These deviations may cause unwanted parasitic effects such as torque ripple, losses or acoustic noise. Such effects have to be considered especially in machines used in industrial drives for high performance applications. Moreover the tolerances in the magnetic materials have a considerable effect on th…