Iron Components Research Articles

Disproportionation Equilibrium of a μ‐Oxodiiron(III) Complex Giving Rise to C−H Activation Reactivity: Structural Snapshot of a Unique Oxoiron(IV) Adduct

Abstractμ‐Oxodiiron(III) species are air‐stable and unreactive products of autoxidation processes of monomeric heme and non‐heme iron(II) complexes. Now, the organometallic [(LNHC)FeIII‐(μ‐O)‐FeIII(LNHC)]4+ complex 1 (LNHC is a macrocyclic tetracarbene) is shown to be reactive in C−H activation without addition of further oxidants. Studying the oxidation of dihydroanthracene, it was found that 1 thermally disproportionates in MeCN solution into its oxoiron(IV) (2) and iron(II) components; the former is the active species in the observed oxidation processes. Possible cleavage scenarios for 1 are shown by scrambling experiments and structural characterization of an unprecedented adduct of 1 and oxoiron(IV) complex 2. Kinetic analysis gave an equilibrium constant for the disproportionation of 1, which is very small (Keq=7.5±2.5×10−8 m). Increasing Keq might by a useful strategy for circumventing the formation of dead‐end μ‐oxodiiron(III) products during Fe‐based homogeneous oxidation catalysis.

Effect of Harvest Times on Rhizoma Yield, Essential Oil Content and Composition in Iris germanica L. Species

Research was conducted to examining the effects of harvest periods on root yield, essential oil content, resinoid content and essential oil composition of Iris species. Iris germanica field in Kuyucak town of Isparta which plant 3 years were constituted in 2016 year as three replications plots according to randomized block experimental design. Harvest was made in the middle each month from April to September (6 periods). Number of rhizomes weight, fresh rhizome yield, dry rhizome yield, essential oil ratio, resinoid ratio and composition in the Iris germanica were determined. In the study, differences between rhizome yield and examining characteristics of Iris germanica according to harvesting periods were statistically significant. Number of rhizomes varied between 3.27-6.47 per plant, rhizome weight 85.55-186.52 g per plant, fresh rhizome yield 972.8-1651.2 kg da-1, dry rhizome yield 212.33-457.50 kg da-1, essential oil and resinoid ratio of rhizome obtained after harvest 0.057-0.076%, 8.00-10.57% essential oil and resinoid ratio in stored rhizomes 0.10-0.14%, 6.95-10.45%, respectively. Rate of α-iron and ɣ-iron components that determine to qualities in essential oil of Iris rhizomes in after harvest varied between 16.1-27.7% and 23.4-50.8% and 29.4-31.2% and 55.2-59% in the essential oil stored rhizomes of Iris germanica, respectively.

Dissolution Behavior of an Iron–Aluminum Double Anode and the Physicochemical Properties of the Dissolution Products

The electrochemical behavior of an iron–aluminum double anode is studied in aqueous sodium chloride solutions. With no applied current, such a double anode has the form of a short-circuited galvanic couple and its surface is nearly equipotential, with the potential being intermediate between the open circuit potentials of individual aluminum and iron electrodes. At low polarization, the applied current almost entirely flows through the aluminum component of the double anode, while at higher polarization the fraction of current through the aluminum component falls and tends to a limiting value that is around twice as high as that for the iron component. This can enable us to control the dissolution rates of aluminum and iron electrodes upon their simultaneous oxidation in a synthesis of metal oxide precursors with a required phase composition by adjusting the ratio of the electrode surface areas.

Analysis of an on-line superconducting cryofan motor for indirect cooling by LH2

This work relates to the study of an electrically powered cryofan for circulating closed-loop cooling helium gas for superconducting applications with the following features:- Absence of any seal that can leak the pumped fluid or provide a path for heat transfer and require maintenance and/or is prone to failures.- The use of high temperature superconducting (HTS) stacks on the fan-rotor that, below critical temperature, can be magnetized contributing to the driving torque.The absence of electrically connected equipment as well as the lack of any seal, makes this arrangement especially suitable for reliable cryogenic helium gas circulation. Because HTS stacks cannot provide magnetic flux above Tc, during the initial stages of operation, in the presented study we analyse the torque that will be provided by the passive iron components of the machine (reluctance torque, due to the saliency of the rotor) and by auxiliary permanent magnets or alternatively magnetizing coils.

Time‐domain computation of rotational iron losses considering the bulk conductivity for PMSMs

This study investigates an advanced finite-element (FE) technique for the evaluation of rotational iron losses based on a time-domain computation, where the bulk conductivity of the core materials is considered. The iron-loss characteristics are discussed for a radial flux permanent magnet synchronous machine (PMSM) for a wind generation application, with closed slots and outer rotor topology. The following factors are taken into account: (i) a real-time rotational iron-loss computation; (ii) the bulk conductivity of the steel laminations; and (iii) the influence of the controller harmonics on the system during transient conditions. The magnetic induction vector locus of each iron component is also discussed, where the magnetic induction is numerically modelled [three-dimensional (3D) finite element analysis (FEA)], computed using multiple magnetic antennae and is also experimentally verified. This comparative study shows a torque–frequency-loss computation that is presented from low to high frequencies (50–800) Hz. The FE model of the total iron losses for the PMSM using both pure sinusoidal and proportional–integral pulse-width modulation currents is studied and experimentally verified on a surface-mounted PMSM. The proposed method of iron losses prediction significantly reduced the rate of error between 3D FEA and experimental data to 1.7%.

Hydrothermal Production of H2 and Magnetite From Steel Slags: A Geo-Inspired Approach Based on Olivine Serpentinization

The interaction between ultramafic rocks and hot seawater at slow-spreading mid-oceanic ridges triggers hydrothermal redox reactions which are known to produce magnetite and H2 under appropriate pressure and temperature conditions. Steel slags share some common properties with ultramafic rocks. They are composed of anhydrous and refractory minerals formed at temperatures exceeding 1200°C and they contain ferrous iron in comparable amounts. Consequently, both types of materials, natural and anthropogenic, when submitted to hydrothermal conditions are prone to form magnetite and H2 according the simplified redox reaction: 3[FeO] + H2O => Fe3O4 + H2 (1) where [FeO] is the ferrous iron component of the corresponding material that can be present under different mineralogical forms. Since H2 and magnetite, Fe3O4, especially when occurring as nanomaterial, are two valuable products for new-technology applications, the hydrothermal treatment of steel slags can be seen as a way to valorize a by-product of the steel industry of which a few tenths of billion tons are produced yearly. The hydrothermal behavior of steel slags which arise from basic oxygen furnace (BOF) operations and that of olivine, (Mg,Fe)2SiO4, the main mineral constituent of abyssal peridotites, is described here based on literature data. The thermochemical characteristics of Reaction 1 are reviewed for both types of materials in the perspective of optimizing a process that would valorize BOF steel slags for the production of nanomagnetite (and high-purity H2). In particular the kinetics effect of temperature, pH and solution-to-solid mass ratio on the hydrothermal oxidation of wustite (FeO), considered here as an analogue of ferrous-iron component of steel slags, is modeled. The possible role of additive (impurity) on the hydrothermal oxidation of wustite though the catalysis of the water-splitting reaction is discussed. Finally, the lack of kinetics constraints on nanomagnetite growth under hydrothermal conditions in a wide range of pH is identified has a major gap to understand two important issues, (1) the catalysis of abiotic molecules in the course of serpentinization reactions and (2) tailoring the size of the magnetite produced by hydrothermal treatment of BOF steel slags.

Performance Comparison and Applicability Analysis of Different Armature Structures for a Small-Scale HTS Linear Synchronous Motor

High-temperature superconducting (HTS) coils could bear larger current density and produce higher magnetic field compared to permanent magnets. An HTS linear synchronous motor (LSM) with its secondary excitation system made of HTS coils can provide larger thrust force but unavoidable larger normal force. This paper focuses on the analysis and comparison of different armature structures in an HTS LSM to improve the magnetic flux waveform quality, decrease the normal force, and simultaneously maintain the thrust force. Five alternative armature structures are proposed and investigated, i.e., coreless double layer lap winding (DLLW), yokeless DLLW, coreless and yokeless DLLW, and flat winding with and without iron yoke. Three dimensional models of HTS LSMs are built and verified to compare the magnetic field and force performances of various armature structures using the finite element method. Results indicate that armatures without iron components perform better. Furthermore, the yokeless flat winding is recommended for its 81% reduction of magnetic flux harmonic component and 52% increase of thrust force compared with DLLW.

Noxious Iron-Calcium Connections in Neurodegeneration.

Iron and calcium share the common feature of being essential for normal neuronal function. Iron is required for mitochondrial function, synaptic plasticity, and the development of cognitive functions whereas cellular calcium signals mediate neurotransmitter exocytosis, axonal growth and synaptic plasticity, and control the expression of genes involved in learning and memory processes. Recent studies have revealed that cellular iron stimulates calcium signaling, leading to downstream activation of kinase cascades engaged in synaptic plasticity. The relationship between calcium and iron is Janus-faced, however. While under physiological conditions iron-mediated reactive oxygen species generation boosts normal calcium-dependent signaling pathways, excessive iron levels promote oxidative stress leading to the upsurge of unrestrained calcium signals that damage mitochondrial function, among other downstream targets. Similarly, increases in mitochondrial calcium to non-physiological levels result in mitochondrial dysfunction and a predicted loss of iron homeostasis. Hence, if uncontrolled, the iron/calcium self-feeding cycle becomes deleterious to neuronal function, leading eventually to neuronal death. Here, we review the multiple cell-damaging responses generated by the unregulated iron/calcium self-feeding cycle, such as excitotoxicity, free radical-mediated lipid peroxidation, and the oxidative modification of crucial components of iron and calcium homeostasis/signaling: the iron transporter DMT1, plasma membrane, and intracellular calcium channels and pumps. We discuss also how iron-induced dysregulation of mitochondrial calcium contributes to the generation of neurodegenerative conditions, including Alzheimer’s disease (AD) and Parkinson’s disease (PD).

Iron bearing oxide minerals separation from rare earth elements (REE) rich coal fly ash

Recovery of Rare Earth Elements (REE) from waste is an important alternative to solve global REE crisis. Therefore, coal fly ash containing REE becomes a potential candidate as an alternative source of REE. Indonesia has a large potential of coal resources, however unlike other type of coals which is rich in SiO2 and Al2O3, Indonesian coal contains significant amount of Fe2O3. As a consequence, fly ash resulted from burning Indonesia coal is also rich in iron oxides. The presence of high concentration of iron oxides will however reduce effectiveness of REE recovery from coal ash through hydrometallurgy process. Therefore, iron oxides in the coal fly ash needs, firstly, to separate preceding further REE separation. This study determined the optimal process conditions in the iron recovery process from coal fly ash. The variables studied were fly ash grain size, magnetic field strength and separation techniques. The iron recovery was determined by mean of the ratio of iron concentration after and before magnetic separation. Experimental results showed that increasing magnetic field strength and decreasing coal fly ash grain size in a wet separation will increase the recovery of magnetic iron component. Magnetic field strength of 4300 Gauss and grain size of -400 mesh were the optimal values in this study with iron recovery of 25.89%.

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

Magnets are important for studying magnetism and are commonly used as sample environment devices of neutron scattering instruments. However, the use of magnets was prevented at the time-of-flight direct-geometry neutron spectrometer 4SEASONS in Materials and Life Science Experimental Facility (MLF) at J-PARC, because the instrument is surrounded by iron components, and it is equipped with a piece of equipment operated with magnetic bearings. In the present work, we investigate the influence of stray magnetic fields from a superconducting magnet which is shared among neutron scattering instruments in MLF. Based on the investigation, we modified 4SEASONS such that it can be used with the magnet. Finally, we successfully performed the first inelastic neutron scattering experiments with applied magnetic fields using this sample environment.

Primary data on the impact from trap magmatism on the hydrogeochemistry of brines in the southwestern part of the Kureyka syncline (Siberian Platform)

The new data on the trap magmatism affecting the hydrogeochemistry of brines in southwestern Kureyka syncline in the west of the ancient Siberian platform are presented. The brines occurring in Paleozoic and Proterozoic deposits have salinity (total dissolved solids) varying broadly: from 30.2 to 469.6 g/dm3 for Na Cl, Na-Ca Cl, Ca-Na Cl, Ca-Mg Cl and Ca Cl types, among which the mixed types (Ca-Na Cl and Na-Ca Cl) are found prevailing. The activity of intrusive trap magmatism in the contact zone (with a strike length of up to 400 m) facilitated the disintegration of organic compounds in the free and water-dissolved form (CH4, C2H6, C3H8, iC4H10, nC4H10, iC5H12, nC5H12, C6H14, I, B, NH4). The reaction of the intruding traps brines interaction significantly affected the initial composition of brines, showing a shift towards their saturation with iron, aluminum, silica and other components and thus bearing the evidence of possible salt-induced metal extraction from magmatic melts into an ore-bearing fluid.

Influence of remaining casting skin on the fatigue strength of cast iron components

The assessment of the fatigue strength of castings with remaining casting skin still constitutes a challenge. Until now, only the roughness of the casting skin has been considered, by a reduction factor, during the design process. This reduction factor, however, neglects the influence of discontinuities such as inhomogeneous microstructures, imperfections, pores etc. In this work, the casting skin represents the rim zone of the casting, consisting of surface roughness and a deviating microstructure.To assess the influence of the casting skin on the fatigue strength, stress- and strain-controlled fatigue tests on EN-GJS-400-15 and EN-GJS-700-2, specimens with deviating casting skins, were conducted. The cyclic behavior of the rim zone microstructure was determined via cyclic axial strain tests under alternating loading Rε = -1 on small flat specimens extracted from the rim zone. For the integration of the results from the axial fatigue tests with the influence of the surface roughness, as well as stress gradients present in cast components, on fatigue strength, cyclic bending tests under alternating Rσ = -1, and pulsating loading Rσ = 0, were performed. The conclusions gained from this work will be transferred in a fatigue assessment concept for the remaining casting skin on cast components.

Optimization and Predictive Modeling of Green Sand Casting Process to Minimize Persisting Defects in GI Components

Quality of castings produced by a sand casting process have always been the result of proper control over an enormous number of parameters involved in the process, while some of the defects are persisting. In the work presented in this paper, the primary focus is on the investigation of the essential parameters of the green sand casting process for effective understanding of most influential parameters which affects the persisting defects in gray cast iron components. The study applies the Taguchi's 'design of experiments' approach for determining the optimal level of parameters to minimise the persisting defects in the foundry industry producing cast components required in the automotive, factory situated in central India. Besides, a mathematical model has been developed using multiple regression analysis for an individual defect. The outcomes of this study assure that the approach used in this work is useful to foundry industries to minimise the casting defects.

Fatigue analysis of cast iron components considering the influence of casting skin

The assessment of the fatigue strength of castings with remaining casting skin still constitutes a challenge. Until now, only the roughness of the casting skin has been considered through a reduction factor during the design process. This reduction factor, however, neglects the influence of discontinuities such as inhomogeneous microstructures, imperfections, pores etc. In this work, the casting skin represents the rim zone of the casting, consisting of surface roughness and a deviating microstructure.To assess the influence of the casting skin on the fatigue strength, stress- and strain-controlled fatigue tests were conducted on EN-GJS-400-15 specimens with deviating casting skins. The cyclic behavior of the rim zone microstructure was determined via cyclic axial strain-controlled tests under alternating loading Rε = -1 on small flat specimens removed from the rim zone. For the integration of the results from the axial fatigue tests with the influence of the surface roughness, as well as stress gradients present in cast components, on fatigue strength, cyclic bending tests under alternating Rσ = -1 and pulsating loading Rσ = 0 were performed. The test results are used to develop a fatigue approach to consider the influence of the rim zone on the fatigue life of cast iron components.

Evaluation of fatigue strength criteria for thick-walled nodular cast iron components from EN-GJS-400 under multiaxial load

This paper discusses the quality of common methods for estimating the fatigue strength of EN-GJS-400-18-LT specimens under multiaxial stress. This is particularly important for the lightweight design of wind turbines. Experimental fatigue tests with axial, torsional and combined loads with a load ratio of R = -1 were performed. The results of these fatigue tests are used to validate commonly used multi-axial stress hypotheses. The investigated methods are the von Mises hypothesis, the Findley-criterion, the modified Gough-Pollard method and the critical plane nominal stress hypothesis.

Efficient removal of several estrogens in water by Fe-hydrochar composite and related interactive effect mechanism of H2O2 and iron with persistent free radicals from hydrochar of pinewood

Recently, hydrochar (HC) with existed persistent free radicals (PFRs) has attracted researches' attention for the potential application in heterogeneous Fenton-like reactions, but studies on the interactive effects of H2O2, iron, and HC in removal of organic pollutants are still limited. In this paper, magnetic iron (hydr)oxides immobilized hydrochar composite (Fe/HC) derived from hydrothermal carbon (HTC) of pinewood were synthesized and characterized. The interactive effects of H2O2, iron, and HC in the removal of several estrogens were systematically investigated to understand the removal performance and related mechanism, especially at a pH range close to natural water environment. Batch experiments results showed that estrogens could be efficiently removed over Fe/HC material under a wide pH range of 4–9. Based on the analysis of electron spin resonance, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, and electrochemical impedance spectroscopy, mechanism study indicated that the carbon-centered PFRs on the surface of hydrochar can act as electron donors, and transfer the electrons on adsorbed O2 to generate O2− rapidly, while the addition of H2O2 enhanced the transmission ability of electron to produce OH(ads) on the material surface. The iron and hydrochar components contributed to the desirable removal of estrogens via the synergistic effect between catalysis and adsorption. This study provides a promising application for the use of Fe/HC materials on remediation of pollution with trace estrogens in water environment.

Improving the corrosion and wear resistance of grey cast iron components by surface welding with duplex stainless steel using regulated gas metal arc welding: Influence of dilution on corrosion properties

Improving the corrosion and wear resistance of grey cast iron components by surface welding with duplex stainless steel using regulated gas metal arc welding: Influence of dilution on corrosion properties

Preparation, characteristics and corrosion properties of α-Al2O3 coatings on 10B21 carbon steel by micro-arc oxidation

Micro-arc oxidation (MAO) as an environmentally friendly technology is used to produce ceramic film on metal surfaces to improve its corrosion properties, and the films quality is mainly affected by the electrolyte composition and electrochemical parameters, Here, to improve the corrosion property and wear-resisting of low carbon steel, a compact, corrosion resistant α-Al2O3 ceramic film was prepared on the surface of low carbon steel containing boron (10B21) by MAO. A Na2SiO3 and NaH2PO4 electrolyte system was designed with different content of Na2CO3 and Na2B4O7. The ceramic layer produced with Na2CO3 and Na2B4O7 showed improved corrosion resistance. The corrosion current density was 2.7 μA·cm−2 and the impedance value reached 1900 Ω·cm2. After 7 days of neutral salt spray corrosion, the corrosion rate of this sample coating reduced to 53 g·m−2·h−1. The influence mechanism is discussed. The cooperation of Na2CO3 and Na2B4O7 in the electrolyte is more effectively regulated the ionization and chemical reactions of the MAO process, catalyzing the formation of α-Al2O3. The coating had a uniform thickness of 100 ± 10 μm, no gap between the coating and the substrate was observed, which indicated that the bonding state was good. Thus, the MAO ceramic layer prepared on low carbon steel surface increases the service life of iron and steel components effectively, which can significantly expand its application in more fields.

Suitability of rice husk ash mould additive for thin wall ductile iron graphite characteristics

Thin wall ductile iron (TWDI) components are used in automobile and related sectors owing to weight savings without sacrificing functional properties. However, its application is hampered by low ductility owing to carbide precipitation and poor nodule characteristics in as-cast structure. In this study, mould thermal characteristics are adjusted using rice husk ash (RHA). Green sand was blended with 1-6 wt. % RHA to produce moulds for casting of 4 mm TWDIs, samples obtained were subjected to microstructural (Optical, SEM and EDS), hardness and strength analyzes. Elemental composition of carbide precipitates showed iron and carbon. Nodularity ratings > 90%, nodule count >1000 nodules/mm2 and strength of 596 MPa were observed in samples cast in 4 wt. % RHA sand mix. Ductility of 6.1 occurred in 6 wt. % RHA/sand mix. The sand-RHA mix offers cooling rate control, reduction of precipitation of deleterious carbides and superior graphite characteristics in 4 mm TWDI castings.Keywords: cooling rate, carbide precipitate, nodules, properties, sand

Preparation of novel iron-loaded microfibers entrapped carbon-nanotube composites for catalytic wet peroxide oxidation of m-cresol in a fixed bed reactor

A novel microfibers entrapped carbon-nanotube composite catalyst with iron loaded (MF-CNT-Fe2O3) was develop followed by fixed bed catalytic wet peroxide oxidation (CWPO) of m-cresol. Firstly, the microfibers entrapped carbon-nanotube composite (MF-CNT) support was prepared by wet lay-up papermaking process and sintering process and the entrapment ratio of support was evaluated. Then active components were loaded on support by metal organic chemical vapor deposition (MOCVD) method. Characterizations were carried out including Field-Emission Scanning Electron Microscope (FE-SEM), Energy Dispersive Spectroscopy (EDS), N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-Temperature-Programmed Reduction (H2-TPR) and Thermogravimetric Analysis (TG), respectively. At last, catalytic activity was tested. Results showed that the best entrapment ratio (72.5%) occurred when stirring time was 9.5 min and the mass ratio of CNTs to stainless steel fibers was 6:3. Characterization results illustrated that advanced three-dimensional network was formed in the microfibers composites and catalysts performed high thermal stability. CNTs were successfully entrapped in the fibers and iron components were uniformly dispersed on supports. CWPO results showed that MF-CNT-Fe2O3 catalysts prepared by MOCVD performed better than by impregnation method. Additionally, MF-CNT-Fe2O3 catalysts could perform high CWPO activity (m-cresol conversion highest at 99% and TOC conversion highest at 42%, respectively). Little iron loss was observed in all treated effluents.