Iron Hollow Research Articles

A study on syntactic aluminum foams manufactured infiltrating sintered preforms of iron hollow spheres

This work analyzes the microstructure, porosity, and mechanical properties of syntactic foams obtained infiltrating 3 mm in diameter Fe hollow spheres with an Al–12Si eutectic alloy. The hollow spheres were first sintered at 800, 900, and 1000 °C for 1h to obtain composite porous preforms, focusing on the effect of this sintering on the manufactured syntactic foams. Results showed that the increase in the sintering temperature led to an increase in the porosity from 51 to 56 %, also increasing the percentage of Fe in the solid part of the foams and decreasing the pore cell thickness. This led to significantly higher strength and a brittle behavior for the foams obtained using spheres sintered at 1000 °C, while the foams manufactured using lower temperatures presented a ductile behavior and lower mechanical properties. α (Al8Fe2Si) and β (Al5FeSi) were obtained during infiltration, decreasing the wall thickness of the Fe spheres.

Rotating speed measurement using an optimized eddy current sensor

This paper presents the rotating speed measurement of solid iron hollow shafts using the optimum design of a rotational eddy current sensor. The rotating speed measurements are performed using the optimized sensor up to ±3000 rpm to evaluate sensitivity enhancement and linearity performance. The sensor is optimized for a shorter axial length and higher sensitivity with a new configuration of the coils. An aluminum shell on a solid shaft is used, which helps to improve the sensitivity and the susceptibility of the sensor to the material properties of solid iron. A 2D analytical method and a 3D time stepping finite element method are considered for the theoretical analysis of the sensor and for an assessment of the effect of this optimization on the performance. The performance of the sensor was verified by measurements. The evaluation of the speed sensor for higher speeds up to ±30,000 rpm is performed using the 2D analytical method.

Application of Substructure Techniques to Syntactic Metal Foams in a Finite Element Environment

The presented work focuses on the development of a novel method that can numerically describe the properties of metal matrix syntactic foam (MMSF) with low memory requirements and short computational times without losing the properties of the interior structure. In this paper, we propose a novel method that avoids using the homogenization technique and instead rearranges stiffness matrices and constructs specific substructures to perform the overall construction. The two-dimensional cases are discussed in order to focus on the methodology itself. First, the reductions and structural design with solid mesh structures were performed, and then the model was applied on structures filled with iron hollow spheres. So far, the method has been used to evaluate small deformations to see how suitable the subspace technique is for describing metal foams. Aluminum was used as the matrix material, as it is one of the most common materials for MMSFs. The optimal parameters were searched that resulted in the shortest running time for the given construction. Since in the proposed substructure technique only the displacement values at the boundary points are computed, a back-calculation step for each selected substructure was performed to see the interior deformations in the vicinity of an iron hollow sphere.

Design, fabrication and operation of a device for manufacturing metal foams and composites by infiltration

This work presents the design and fabrication of a simple device for manufacturing metal foams and composites using infiltration. The particularities of the operation of this device are also included here, detailing examples of materials manufactured using it. This device was thought to produce composites and foams using matrices from low to medium melting points (e.g., from Mg to Cu alloys), limited to ~1200 °C. It can be used to produce samples large enough for their study and characterization, being cheaper than other devices reported in literature. Foams and composites of different sizes can be manufactured depending on the dimensions of the device, which can be modified according to the necessities. As examples, cylindrical (10 cm height and 5 cm in diameter) samples were manufactured infiltrating Al and Cu alloys on NaCl, NaCl-Al2O3 spheres mixture, and iron hollow spheres, for manufacturing respectively conventional, composite and syntactic foams. These materials were analyzed through Optical and Scanning Electron Microscopies (OM and SEM, respectively), and compression tests. Their densities and porosities were also measured. The analysis of the obtained materials revealed that following the correct experimental conditions, composites and foams without defects can be manufactured using this device. Different porosity and reinforcement percentages were obtained under these conditions, with the expected mechanical behaviors of such materials.

Hollow iron submicron spheres with strong ferromagnetism

Hollow iron submicron spheres with high saturation magnetization at room temperature were successfully developed for the first time. By means of spray pyrolysis, α -Fe2O3 hollow spheres with the diameter ranging from 0.5 µm to 2.5 µm and an average shell thickness of approximately 20 nm could be obtained in large scale. In subsequent reductive annealing under dilute hydrogen atmosphere, as-synthesized α -Fe2O3 can be transformed into Fe3O4, unstable FeO, and Fe in sequence with an increase in annealing temperature from 350 °C to 600 °C. An optimal reductive temperature of 425 °C was proposed to obtain perfect iron hollow spheres showing a maximum saturation magnetization up to 184 emu/g, which is greater than literature reported values and can be ascribed to curvature effect and symmetrical structural feature.

Reference wavelengths of Si ii, C ii, Fe i, and Ni ii for quasar absorption spectroscopy.

Wavelengths of absorption lines in the spectra of galaxies along the line of sight to distant quasars can be used to probe the variablility of the fine structure constant, α, at high redshifts, provided that the laboratory wavelengths are known to better than 6 parts in 108, corresponding to a radial velocity of ≈20 ms-1. For several lines of Si ii, C ii, Fe i, and Ni ii, previously published wavelengths are inadequate for this purpose. Improved wavelengths for these lines were derived by re-analysing archival Fourier transform (FT) spectra of iron hollow cathode lamps (HCL), a silicon carbide Penning discharge lamp, and with new spectra of nickel HCLs. By reoptimizing the energy levels of Fe i, the absolute uncertainty of 13 resonance lines has been reduced by over a factor of 2. A similar analysis for Si ii gives improved values for 45 lines with wavelength uncertainties over an order of magnitude scer than previous measurements. Improved wavelengths for eight lines of Ni ii were measured and Ritz wavelengths from optimized energy levels determined for an additional three lines at shorter wavelengths. Three lines of C ii near 135 nm were observed using FT spectroscopy and the wavelengths confirm previous measurements.

Elastic Modulus Estimation for Copper Syntactic Foams Reinforced with Iron Hollow Spheres of Different Wall Thicknesses

The present study estimates the effect on Young’s modulus of the percentage and thickness of iron hollow spheres reinforcing copper syntactic foams. The resulting materials were modeled by inserting hollow spheres in a random arrangement, using a combination of Discrete Element Method (DEM) for generating the sphere location coordinates and Finite Element Analysis (FEA). Estimations for syntactic foams were compared to those obtained for conventional copper foams with the same porosity. Results showed that the elastic modulus of both syntactic and conventional foams drops significantly as the percentage of spheres or porosity increases. Furthermore, the increase in the wall thickness of the iron hollow spheres leads to significant rises in the Young’s modulus. Depending on the desired mechanical properties, the outcomes presented in this work could be used for selecting the kind of foam (syntactic or conventional) and predesign some characteristics such as porosity or thickness of the spheres or pores.

Inductive heating of fluidized beds: Mobile versus stationary heat exchange elements

Fluidized beds play an important role in many industrial processes due to their very good heat and mass transfer. Usually heated convectively, inductive energy input is a promising alternative utilizing an electromagnetic field and an electrically conductive material [e.g. mobile iron hollow balls (IHB) or stationary iron tube (IT)]. In this research article, the heat exchange between moving IHB or stationary tube and the fluidizing medium or substrate is modeled. Very good correspondence is achieved between calculated and experimental results.

The investigation of drilling an aluminium matrix composite reinforced with iron hollow spheres

Since composites have numerous advantages, they have a prominent role in manufacturing. That is the reason why they might substitute conventionally used materials. Nowadays cutting processes are among the most commonly used finishing technologies. In the case of composites the cutting tools have to meet particular requirements. This paper represents the machinability examinations of a special type of composites – iron hollow sphere-filled aluminium alloy matrix (AlSi12) – during drilling. The input cutting parameters, the feed (f, mm) and the cutting speed (vc, m/min), were varied at a wide range according to a design of experiment (a full factorial design was used). Drilling studies were carried out under dry conditions and with internal cooling lubrication as well. The axial (feed) force (Ff, N) was measured. Based on the experimental results, the different drilling conditions were compared. In addition, a proposal is made for cutting this kind of material. The joint properties of the aluminium matrix and the iron hollow spheres during cutting were examined by scanning electron microscopy.

Multipurpose Low Cost Table Machine

The concept of this paper is to develop idea of multipurpose machine as by conducting various operation on same machine, using single operating system. Here, in this machine there is a electric motor which is connected to the pulleys driven by belt (more than one pulley for various speed). The pulley is connected with the shaft which rotate in circular motion and to this shaft circular tools are connected as per required operation as circular saw cuts wooden pieces, pipe cutter will cuts iron rod or iron hollow pipe, grinding circular wheel grinds the job, polishing wheel polishes the job etc. more types of tools and the operation can be done on the same machine. The idea of this machine is to motivate small scale house hold units for ex. Furniture making, office table, Chair, show case for wedding ceremony etc. with low cost machines with multipurpose operation done on same machine.

Wavelength calibration of narrowband ArF laser with iron hollow cathode lamp

Accurate and precise wavelength controlling of narrowband excimer lasers is essential for the lithography of an integrated circuit. High-precision wavelength tuning and calibration of a line-narrowed ArF laser are presented in this work. The laser spectrum is narrowed to a sub-picometer with a line narrowing system. Absolute wavelength calibration of the line-narrowed laser is performed based on the optogalvanic (OG) effect using iron hollow cathode discharge (HCD). An sccuracy of better than 0.1 pm for wavelength tuning and calibration is achieved with our homemade wavemeter.

Estimating the base material properties of sintered metallic hollow spheres by inverse engineering procedure

The base material properties of single sintered metallic hollow spheres cannot be determined directly because of their small size, with the outer diameter ranging from 1 to 15mm. The paper proposes an inverse engineering procedure for their determination by applying the computational optimisation based on an extensive experimental testing data. Initially, the compressive response of single iron hollow spheres of selected sizes of 2 and 3mm in diameter has been determined by quasi-static and dynamic experimental testing. The exact geometrical data of the analyzed spheres was obtained by μCT scanning and then used for creation of the corresponding FE models. These were subjected to the same loading conditions in computational simulations as those used in experimental testing. The non-gradient optimization process based on genetic algorithm was applied to define appropriate base material properties of analyzed spheres, which returned the same response of computational models as the one recorded in experiments. This way the base material properties of sintered iron hollow spheres were obtained for the first time, which can be used for computational studies of the metallic hollow sphere structures behavior.

Compressive Behavior and Microstructural Characteristics of Iron Hollow Sphere Filled Aluminum Matrix Syntactic Foams.

Iron hollow sphere filled aluminum matrix syntactic foams (AMSFs) were produced by low pressure, inert gas assisted infiltration. The microstructure of the produced AMSFs was investigated by light and electron microscopy, extended by energy dispersive X-ray spectroscopy and electron back-scattered diffraction. The investigations revealed almost perfect infiltration and a slight gradient in the grain size of the matrix. A very thin interface layer that ensures good bonding between the hollow spheres and the matrix was also observed. Compression tests were performed on cylindrical specimens to explore the characteristic mechanical properties of the AMSFs. Compared to other (conventional) metallic foams, the investigated AMSFs proved to have outstanding mechanical properties (yield strength, plateau strength, etc.) and energy absorbing capability.

Compressive behaviour of aluminium matrix syntactic foams reinforced by iron hollow spheres

Aluminium alloy syntactic foams reinforced with iron hollow spheres were produced by low pressure, liquid phase inert gas infiltration technique. Four Al alloys (Al99.5, AlSi12, AlMgSi1 and AlCu5) and Globomet grade iron hollow spheres were used as matrix and reinforcing material, respectively. The produced composite blocks were characterised according to the ruling standard for compression of cellular materials in order to ensure full comparability. The compressive test results showed plastic yielding and a long, slowly ascending plateau region that ensures large energy absorption capability. The proper selection of the matrix material and the applied heat treatment allows for a wide range of tailoring of the mechanical properties. For design purposes, the full-scale finite element method (FEM) model of the investigated foams was created and tested on Al99.5 matrix foams. The FEM results showed very good agreement with the measured values (typically within 5% in the characteristic properties and within 10% for the whole compression curve).

Mechanical Properties of Iron Hollow Sphere Reinforced Metal Matrix Syntactic Foams

Metal matrix syntactic foams (MMSFs) were produced by low-pressure inert gas infiltration technique. Matrixes of the produced syntactic foams were Al99.5, AlSi12, AlMgSi1 and AlCu5 respectively, and each was reinforced by pure Fe based hollow. The produced blocks were investigated by optical and scanning electron microscopy. The microstructural investigations revealed proper infiltration with small amount of unwanted voids and an effective and thin interface layer between the matrix materials and the reinforcing spheres. The produced MMSFs were also tested under quasi-static compression loading to get characteristic mechanical properties. The test results showed that the MMSFs with iron spheres have outstanding mechanical properties compared to ‘conventional’ foams.

Fabrication of Iron Hollow Spheres by Reduction Sintering Process

Iron hollow spheres were fabricated by reduction sintering process. The reduction of iron oxide completed in a range from 573 to 973 K, and the shrinkage (sintering) advanced rapidly in a range from 673 to 1073 K. In spite of the large shrinkage, the shape of sintered body showed only an at all small distortion from a sphere. The compression curve of the block which joined iron spheres showed the plateau load region where a load change is small, and the average plateau load strongly depends on the compression strength of unit spheres. By means of chemical reaction controlled un-reacted core model, activation energy of reduction process has been estimated to be 22 kJ/mol.

中空鉄ボールと円柱状成型体の圧縮変形挙動

Iron hollow spheres (IHSs) were manufactured by the reduction of iron oxides. The compressive deformation behavior and structures of IHS were systematically investigated. The strength of IHSs is proportional to the product of the IHS diameter and the shell thickness of IHSs, and is equivalent to the buckling strength of the IHS structure. A plateau stress region is observed during the compression of the IHS structure. The plateau stress is proportional to the strength of IHSs. The bonding of IHSs is indispensable to the occurrence of the plateau stress region. The average plateau stress does not depend on the distribution of the IHS strength but depends on the average IHS strength. The plateau stress decreases in the inclined compression of the IHS structure. The plateau stress increases with an increase in the strain rate during the compression. Its increasing ratio is larger than that of the porous aluminum.

鉄中空球成形体の焼成実験とシミュレーション

鉄中空球成形体の焼成実験とシミュレーション

鉄中空球の高温圧縮特性

鉄中空球の高温圧縮特性

Corrosion behaviour of coated cellular material

AbstractCellular solids are developed, improved and investigated in connection with the search for new lightweight structural materials. Interest in the applications of lightweight metal foams and novel cellular materials is rapidly increasing. They can be used as components in heat exchangers, as weight‐saving constructive elements, deformable energy absorbers, catalyst surfaces, filters, etc.Metal foams (or cellular solids) can be produced by a variety of methods. The regular‐structured cellular material might be accessible by powder metallurgical methods, using hollow powder. The metal coatings can be applied to improve the mechanical properties, surface morphology, and wear and corrosion resistance of basic materials.In this contribution the corrosion behaviour of copper + nickel coatings on the iron hollow particles has been studied. Electrodeposition of one‐component Ni and then Cu coatings and binary NiCu coatings were realized in a fluidized bed. Also the deposition of copper by cementation was investigated. The main attention was focused on the combination of electroless deposition of Cu and electrolytic deposition of Ni. The corrosion resistance of the coatings was investigated by using SEM and ToF‐SIMS methods. Copyright © 2004 John Wiley & Sons, Ltd.