Iron Substrate Research Articles

Wetting and spreading behavior of molten iron in contact with graphite substrate: Interfacial effects

The dissolution of carbon from coke into molten iron is a critical factor influencing melting efficiency and lining erosion of blast furnaces. To gain an in-depth understanding of this process, the wetting and spreading behaviors of molten iron in contact with a graphite substrate were studied using high-temperature vacuum wettability test equipment and a microstructural analysis method. The results show that the initial contact angles of molten iron on a graphite substrate (105.8°, 116.7°, 122.0°) and the equilibrium contact angles (60.6°, 65.4°, 70.7°) increase with increasing initial carbon content (Fe-3.8%C, Fe-4.3%C, Fe-4.8%C), showing a certain dependence on the carbon content in the molten iron. The initial stage of interaction between the molten iron and graphite substrate is a non-wetting state, which transitions to a wetting state during the spreading stage at high temperatures. A spherical cap structure is formed because of interfacial effects. The results show that the penetration of carbon into the molten iron decreases with increasing initial carbon content. Finally, the wetting and spreading mechanisms are illustrated on the basis of interfacial energy analysis. It is mainly controlled by dissolution in the initial stage of wetting and spreading, then transfers to reaction-driven control.

Microstructure and Fracture Toughness of Compact TiC-Fe Gradient Coating Fabricated on Cast Iron Substrate by Two-Step In Situ Reaction

A compact TiC-Fe gradient coating with high hardness and toughness has been fabricated on cast iron by two-step in situ reaction. The phase constitution of the coating was TiC and α-Fe. As the thickness of the coating was increased, the size (about 6.34 μm to 0.54 μm) and volume fraction of TiC particles gradually decreased. The formation mechanism of TiC was nucleation-growth of TiC grains (the first step of the in situ reaction) and the diffusion-type solid-phase transition via diffusion of carbon atoms into the titanium lattice (the second step of the in situ reaction). From the surface of the coating to the coating–substrate interface, the hardness and elastic modulus gradually decreased from 30.74 ± 0.61 GPa and 438.47 ± 4.82 GPa to 21.67 ± 1.03 GPa and 380.71 ± 5.86 GPa, respectively. Meanwhile, t he fracture toughness gradually increased from 3.21 MPa m1/2 to 6.75 MPa m1/2.

A Low-Cost Iron-Based Current Collector for Alkaline Battery Electrodes

The use of three-dimensional porous nickel foam as the current collector of the nickel hydroxide electrode adds significantly to the cost of the nickel-based alkaline rechargeable batteries. Although iron is considerably less expensive than nickel, iron corrodes at the operating potential of the nickel hydroxide electrode. We have found that a 70–100 nm thick thermal coating of cobalt ferrite spinel protects the iron from corrosion. Such a coated iron substrate was found to be stable against corrosion even when polarized anodically at 10 mA cm−2 in 30% potassium hydroxide electrolyte for 1000 h. While the thermal coating of cobalt ferrite protected iron against corrosion, incorporation of lithium ions into the coating was found to enhance the electrical conductivity of the coating. XPS and EXAFS studies confirmed that the enhanced conductivity resulted from an increase in the population of Co3+ in the ferrite spinel lattice. An inexpensive iron (steel) substrate protected by such a coating when used as a nickel hydroxide battery electrode exhibited a specific capacity of 0.25 Ah g−1 at C/5 discharge rate, comparable to a nickel hydroxide electrode based on a relatively expensive nickel foam substrate. The steel-based electrode also exhibited no noticeable degradation over 150 cycles at C/2 rate. This demonstration of a robust and economical steel substrate presents a unique opportunity for reducing the cost of the nickel hydroxide battery electrode in alkaline batteries.

Micro-Cracking in Medium-Carbon Steel Layers Additively Deposited on Gray Cast Iron Using Directed Energy Deposition

Single track and multi-layers of medium-carbon steel (AISI H13) powders were additively deposited on gray cast iron using a directed energy deposition (DED) technique. Multi-scale microstructure characterization using a scanning electron microscopy, an electron probe micro-analyzer and a scanning transmission electron microscopy, and the thermal analysis using finite element method were performed to understand the mechanism for the micro-crack formation, which was found at the single, double and triple layers of medium-carbon steel powders, except for the single track, deposited on a cast iron substrate. The crack formation mechanism was thoroughly investigated by combining the layer-by-layer chemistry variations and the resulting microstructural evolution upon exposure to thermal cycles during the DED process. It was concluded that micro-cracking was accompanied by the initiation of the local graphitization and the formation of plate martensite in the vicinity, which seemed to be kinetically facilitated by an indirect exposure to multiple heating–cooling thermal cycles, not by a direct exposure to a melting-cooling (solidification) cycle.

Facile Synthesis of an Efficient Ni–Fe–Co Based Oxygen Evolution Reaction Electrocatalyst

Electrolytic water splitting offers energy storage and conversion opportunities, yet the slow kinetics of the oxygen evolution reaction requires the incorporation of catalytic materials. Herein, we present a facile method for the synthesis of a low-cost Ni-Fe-Co material that efficiently catalyzes the oxygen evolution reaction. A mixed transition metal electrocatalyst was synthesized using a nickel-plated iron substrate and a low concentration cobalt reagent. The catalyst was able to achieve competitive current densities (>130 mA cm−2) and still exhibit a low overpotential of 0.30 V at the benchmark current density of 10 mA cm−2. The Ni-Fe-Co catalyst was stable and maintained its activity during 24 h of electrolysis in alkaline media. The catalyst was also stable when maintained in ambient conditions for 90 days. This is the first reported oxygen evolution reaction catalyst that exhibits these competitive characteristics and that was synthesized using an environmentally-conscious, one-step process that can be manufactured on an industrial scale.

400 Relationship between Cardiac Iron and Altered Myocardial Substrate in Patients With Chronic Kidney Disease – Non-Invasive Assessment With CMR.

Patients with chronic kidney disease (CKD) are at increased risk for cardiovascular complications, and dialysis patients often receive iron supplementation. Cardiac magnetic resonance (CMR) allows evaluation of cardiac function, fibrosis and iron deposition. We used CMR to explore mechanistic links between cardiac iron and abnormal myocardial substrate in patients with CKD. Cardiac function and morphology, tissue characterisation and iron deposition were compared in 24 healthy controls,10 patients with CKD stage 3-5, and 30 patients dialysed for >1 year. There were no between group differences in left ventricular (LV) ejection fraction (65±5 v 62±7 v 61±10%, p=0.908), end diastolic volume (84±16 v 69±13 v 76±22 ml/m2, p=0.532) or left atrial size (21±5 v 22±4 v 23±7m2, p=0.473). LV mass (58±13 v 66±9 v 76±27 g/m2, p=0.005) and global longitudinal strain (-22±3 v -20±4 v -14±4%, p<0.001) were abnormal in the dialysis group, but not the CKD group. Native T1 and T2 times were increased in both CKD and dialysis patients (ShMOLLI 1127±43 v 1189±37 v 1223±61ms, p<0.001; and T2 FLASH 35±2 v42±4 v 39±2ms, p<0.001). No group had significant iron deposition by T2-star. Despite no significant myocardial iron deposition, CMR detects abnormal myocardial structure and function across the spectrum of CKD, with abnormal global longitudinal strain seen only in dialysis patients. CMR may aid in identifying CKD patients at higher risk of adverse cardiac outcomes.

Expedient iron-catalyzed stereospecific synthesis of triazines via cycloaddition of aziridines with diaziridines.

Iron-catalyzed stereospecific [3+3]-annulation of aziridines with diaziridines is described to furnish [1,2,4]-triazines in high yield at room temperature. The use of an inexpensive iron salt catalyst, substrate scope and enantiomeric purity are the important practical features.

Hydrophobic Properties of Polymer Films on Cast Iron Substrates

Author(s): Villa, Syndee; Broome, Dewayne | Abstract: The properties of hydrophobic surfaces have been of recent interest due to their applications in cookware and automotive components. The wetting properties of surfaces usually have an effect on the frictional forces due to the surface roughness of a material and the degree of wetting it creates. Non-stick in cookware has been used because it is easier to clean, cook, heats the food evenly, and requires less oil each time it's used which makes it a healthy alternative. For the cookware the necessity arises from users not wanting food or debris to stick to their surfaces and the automotive necessity arises from the need of car parts to maintain their tolerances in order for them to function properly. This study aims to explore the surface chemistry properties of cast iron in these applications where we measure contact angles between water molecules, observe the microstructure, and measure frictional and adhesion forces to a grey cast iron sample with deposited oil layer. Our main goal is to design and quantify the hydrophobic properties of a cast iron surface.

Forming the Fe(Se1 –xTex) Superconducting Coatings on the Iron Surface

The Fe(Se1 –xTex) superconducting coatings have been deposited onto the surface of strip and ribbon iron substrates from chalcogen vapors and chalcogenide melt. The obtained coatings have a β-phase structure of the FeSe compound and critical superconductivity parameters similar to those of bulk polycrystals. It is shown that the coatings must be deposited from the compositions containing Se and Te and the optimal substrate is pure iron. The magnetic field dependences of the magnetic moments of the coatings have been measured and the critical current density has been estimated. At T = 4 K in fields of more than 4 T, the critical currents of the coating of both types are about 103 A/cm2 and weakly change with an increase in the magnetic field.

Формирование сверхпроводящих покрытий Fe(Se-=SUB=-1-x-=/SUB=-Te-=SUB=-x-=/SUB=-) на поверхности железа

To obtain superconducting coatings Fe(Se1 − xTex) on the surface of iron substrates (strip, tape) two techniques have been used: deposition of coatings from chalcogen vapor and deposition of coatings from a melt of chalcogenides. The resulting coatings had a β-phase structure of the FeSe compound and critical superconductivity parameters close to those of bulk polycrystals. It was shown that for deposition of coatings is mandatory to use compositions including Se and Te, and the optimal substrate is pure iron. The critical current density of coatings were estimated using the magnetic moments dependences on the magnetic field. At T = 4 K and fields greater than 4 T, the critical currents were of the order of 103 A / cm2 for both types of coatings and change slightly with increasing magnetic field

Adhesive contact of a diamond sphere with an iron substrate caused by interatomic interaction

By incorporating the adhesive force as a body force in the finite element method, the adhesive contact between a diamond sphere and the iron substrate is studied. The adhesive force is derived from Morse potential by integrating the pair potential function over the spherical domain. Based on the tensile behaviors of iron nanowires, the elastic and elastoplastic material parameters are obtained for the substrate. As the radius of the sphere is larger than 320 nm and the maximum depth of indentation is one-tenth of the radius of the sphere, the adhesion caused by interatomic interaction between diamond and iron is small enough to ignore. Then take the sphere whose radius is 20 nm as an example, the results of a single load–unload cycle and multiple load–unload cycles are discussed. In the contact process between the sphere and the surface, the phenomena jump-to-contact and jump-off-contact were observed. Further, the stress distributions inside the substrate and the pressure distribution are investigated. With the analysis of the results, the proposed method can be used to simulate the mechanical behaviors under micro-nano scale contact.

Corrosion‐resistant coating of iron: A synergistic effect of electroactive poly(triphenylamine) coating with posttreatment for high‐corrosion‐protection efficiency

AbstractAbstractAn electroactive poly(triphenylamine) (PTPA‐C6) is applied to the surface of iron as a corrosion‐protection layer. The iron substrate coated with PTPA‐C6 is thermally treated at different temperatures (up to 80°C) to study the effect of thermal treatment of PTPA‐C6 on the corrosion behavior of iron. Experimental results indicate that the contact angle of the PTPA‐C6 film increases from 81.6° at room temperature to 100° after thermal treatment at 80°C for 1 hr. The surface becomes more hydrophobic after thermal treatment, which will lower the penetration of water to the iron surface. Adhesion tests (ASTM 3359) indicate that adhesion between the PTPA‐C6 and iron substrate is enhanced after thermal treatment. Additionally, a thin iron oxide layer formed between the PTPA‐C6 and iron substrate as a passivation layer. The synergistic effect of these factors makes PTPA‐C6 a very effective corrosion protection layer on iron substrate after appropriate thermal treatment. Corrosion protection efficiency increases from 90% of the pristine PTPA‐C6 to 99.9% of the 80°C treated PTPA‐C6.

4-O-methylascochlorin stabilizes hypoxia-inducible factor-1 in a manner different from hydroxylase inhibition by iron chelating or substrate competition.

Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that plays essential roles in human diseases including cancer. The synthetic ascochlorin derivative 4-O-methylascochlorin stabilizes HIF-1α protein, and activates its transcriptional activity, resulting to induce gene expression of its downstream targets such as VEGF and GLUT-1. Here, we quantified protein level of HIF-1α in human osteosarcoma U2OS cells treated with ascochlorin-related compounds and typical HIF-1α stabilizers to characterize properties of HIF-1α stabilization by 4-O-methylascochlorin. Structure-activity relationship studies suggested that the aromatic moiety and hydrophobic substitution of the 4'-hydroxyl group are important for HIF-1α stabilization by ascochlorin-related compounds. 4-O-Methylascochlorin-induced HIF-1α stabilization was suppressed by ascorbic acid and compound C, but not by Fe(II), whereas ascorbic acid only suppressed HIF-1α stabilization by dimethyloxaloylglycine, an analog of the HIF-1 hydroxylase substrate. Fe(II) completely suppressed iron chelator-induced stabilization. These results suggest that ascochlorin-related compounds stabilize HIF-1α in a manner distinct from iron chelating or substrate competition.

Growth kinetics and mechanical properties of the V2C and V8C7 carbide layers on iron substrate

To explore the formation of vanadium carbide layers (V2C and V8C7) on the surface of an iron-based alloy produced by a diffusion-controlled in situ reaction in the solid state from 950 °C to 1050 °C, the growth kinetics of the V2C and V8C7 layers were evaluated based on the diffusion. The experimental results reveal that the growth of vanadium carbide layers is controlled by carbon diffusion from the iron substrate to the thin vanadium plate, where the growth kinetics of the V2C and V8C7 layers exhibit a parabolic growth law. Simultaneously, it is also accompanied by vanadium and iron diffusion. The results for the obtained diffusion coefficient and the growth activation energy indicate that the diffusion mechanism of carbon in the V2C layer and V8C7 layer is predominantly grain boundary diffusion and that the formation of the V8C7 layer needs to overcome a higher energy barrier than that of the V2C layer. Additionally, the precipitated phase σ-FeV is found to be located at grain boundaries of the V8C7 layer. Investigations into the mechanical properties by indentation technology show that the hardness and Young's modulus of the V8C7 layer are slightly greater than those of the V2C layer. The fraction toughness of the dominant V8C7 layer with values from 0.88 to 4.34 MPa·m½ decreases with the increasing load. The precipitated phase σ-FeV exhibits an effect on the hardness and fraction toughness. The obtained double vanadium carbide layers improve the mechanical performance of the surface of the iron-based alloy.

Graphene Adhesion Mechanics on Iron Substrates: Insight from Molecular Dynamic Simulations

The adhesion feature of graphene on metal substrates is important in graphene synthesis, transfer and applications, as well as for graphene-reinforced metal matrix composites. We investigate the adhesion energy of graphene nanosheets (GNs) on iron substrate using molecular dynamic (MD) simulations. Two Fe–C potentials are examined as Lennard–Jones (LJ) pair potential and embedded-atom method (EAM) potential. For LJ potential, the adhesion energies of monolayer GN are 0.47, 0.62, 0.70 and 0.74 J/m2 on the iron {110}, {111}, {112} and {100} surfaces, respectively, compared to the values of 26.83, 24.87, 25.13 and 25.01 J/m2 from EAM potential. When the number of GN layers increases from one to three, the adhesion energy from EAM potential increases. Such a trend is not captured by LJ potential. The iron {110} surface is the most adhesive surface for monolayer, bilayer and trilayer GNs from EAM potential. The results suggest that the LJ potential describes a weak bond of Fe–C, opposed to a hybrid chemical and strong bond from EAM potential. The average vertical distances between monolayer GN and four iron surfaces are 2.0–2.2 Å from LJ potential and 1.3–1.4 Å from EAM potential. These separations are nearly unchanged with an increasing number of layers. The ABA-stacked GN is likely to form on lower-index {110} and {100} surfaces, while the ABC-stacked GN is preferred on higher-index {111} surface. Our insights of the graphene adhesion mechanics might be beneficial in graphene growing, surface engineering and enhancement of iron using graphene sheets.

Modelling of Mossbauer spectra of layered metal systems obtained by ion-plasma sputtering

The layered Zr(2 μm)-Fe(10 μm), Sn(4 μm)-Fe(10 μm) and Sn(4 μm)-Zr(2 μm)-Fe(10 μm) systems subjected to isochronous annealings have been studied. The sequence of phase transformations is determined. In the three-layer system, the formation of intermetallic compounds with a high content of Zirconium and a solid solution α-Fe(Sn, Zr) is established. The spectra of 57Fe nuclei in Iron-based alloys of various concentrations were calculated. A comparison with the experimental spectra of the layered systems obtained by ion-plasma deposition of Tin and Zirconium on an armco iron substrate and subjected to thermal annealing at 750 °C showed a good correlation.

Study on Laser Cladding Preparation of Bionic Surface of Cast Iron Brake Disc

The shellfish in nature was taken as the biological model, and the coupling design was carried out on the surface of grey cast iron. With the help of advanced laser cladding technology, the unit body was prepared on the surface of grey cast iron, so as to obtain the bionic samples of grey cast iron with high wear resistance and fatigue resistance. The composition, hardness distribution, morphology and phase of the unit were analyzed by micro-hardness tester, scanning electron microscopy (SEM) and XRD. Thermal fatigue test and friction and wear test were carried out on bionic and untreated grey cast iron samples. The effects on fatigue resistance and wear resistance of bionic laser cladding and grey cast iron were studied by comparing the experimental results. It was found that the laser cladding has a compact structure and a metallurgical bond with the substrate. The hardness of the unit is 2 times of that of the grey cast iron substrate. The thermal fatigue resistance of the material is improved by bionic laser cladding. The bionic laser cladding preparation can greatly improve the wear resistance of materials.

Addressing the Vepris verdoorniana complex (Rutaceae) in West Africa, with two new species

SummaryVepris verdoorniana (Rutaceae) has long been regarded as a widespread and variable species occurring from Guinea to Gabon. Recent evidence has shown that the original material from the type locality in Cameroon consists of two different species, V. verdoorniana in the strict sense, endemic to Lower Guinea (Cameroon, Gabon and C.A.R. in W-C Africa) and V. letouzeyi Onana, which was thought to occur from Guinea to Cameroon. In this paper we show that the West African (Upper Guinea) material previously referred to as V. letouzeyi/V. verdoorniana is separate morphologically from that in Cameroon (Lower Guinea). In fact the West African material referred to comprises two distinct species, here described as V. occidentalis Cheek & Onana (Guinea to Ghana, but probably extending to Benin) a tree of lowland marginal dry evergreen and semi-deciduous forest, and V. fer Cheek, a species restricted to four mainly lower submontane forest locations on iron substrates in Liberia and Sierra Leone (also Upper Guinea). Vepris occidentalis is here assessed as Least Concern due to its wide range and high frequency, whilst V. fer is assessed as Endangered due to the low number of locations and threats from iron ore mining projects. Both new species are illustrated and mapped.

Creep strength of Al2O3 + ZrO2·5CaO subjected to thermal cyclic test

The present paper examines the failure mechanism of the coating system of Al2O3–ZrO2·5CaO applied on a Cast iron substrate. The atmospheric plasma spray coating technique was used for coating. A muffle furnace was used to heat the sample to 600 ± 2 °C followed by ambient cooling. Both the heating and cooling cycles were maintained for 30 min. Results were compared between the as-sprayed coated specimen and the post thermal cyclic test specimen. It has been noticed that normal stresses developed due to the formation of thermally grown oxide at the interface of the top/bond coat and constitutes the weakest link in the coating system. Also, differential porosity at the interface led the moisture to penetrate from the top coat to the bottom coat. Thus, a thermochemical process occurred below the bond coat, leading to the formation of oxides and made the top coat gradually more brittle during the thermal cyclic process.

Preparation of Metal-Gr Composite Coatings Via Electro-Plating for High Corrosion Resistances

1) Preparation of Fe-Gr composite coating via DC electro-plating for high performances. In this work, the iron-graphene (Fe-Gr) composite layer was prepared by using an electro-plating method. The performance of the composite was varied with the concentrations of GO in the electrolyte. The layer’s microstructures were systematically characterized by SEM, TEM, Raman, FT-IR, and the micro-hardness and its corrosion resistance were evaluated for getting desired properties. The experimental results revealed that: 1) the Gr could be scattered homogeneously in the Fe layer when dispersible graphene oxide (GO) was added in the electrolyte; 2) comparing with pure Fe layer, the micro-hardness and corrosion resistance of the Fe-Gr composite layer were greatly enhanced; 3) it was found that there was an optimal GO addictive amount (0.4 g/L) in the electrolyte, which increased the properties involving the micro-hardness up to HV 248, 2.07 times higher than that of pure iron layer(HV 120); 3.75 times of anti-corrosion rate(0.1353 mmy-1) and 5.38 times of the charge transfer resistance(1456 /(Ω·cm2) higher than that of pure iron layer(0.5076 mmy-1, 270.5 /(Ω·cm2). 2) Preparation of Zn-Gr composite coating via pulse reverse electro-plating for high corrosion resistances. In this work, a kind of the Zn-Gr composite layer is successfully prepared on iron substrate via pulse reverse electro-plating method from a chloride aqueous solution. The experimental results revealed that: 1) By adding GO in the electrolyte, Gr sheets can be incorporated homogenously in the Zn plating layer during electro-plating, and the reduction from GO into Gr occurs due to the Zn and GO co-deposition. 2) Due to increasing of the nucleation sites, Gr incorporation changes the growth mechanism of Zn crystal, i.e., makes the main preferred orientations from (112) and (101) crystal planes in the pure Zn layer into (103), (102) and (110) planes in the Zn-Gr composite layers. 3) As a corrosion protection barrier layer, Gr sheets play an important role on the corrosion resistance of the Zn-Gr composite plating layers in simulated seawater environment. The highest corrosion resistant properties occur in an optimal range 0.3 – 0.5g/L GO adding amount in the electrolyte, at which the corrosion current density just be a hundredth comparing with that of pure Zn layer. 4) The present method for preparing Zn-Gr composite, with advantages of simple, controllable, scalable, etc., is likely to be industrialized.