Thin Iron Layers Research Articles

Alumina-based ceramic coatings obtained by the SHS process for high temperature corrosion and wear protection of steel tubulars

Ceramic coatings have much potential for steel tubulars' protection against high temperature corrosion of gases and liquids, often containing abrasive solid particles, and to enhance their integrity in severe power generation, mineral and oil & gas production environments. Combining self-propagating high-temperature synthesis (SHS) with high-speed centrifugal process, alumina-based coatings were produced onto the inner surface of tubulars for these applications. According to the developed SHS batch formulation and the designed centrifugal device and process, well-consolidated composite ceramic layers with a thickness of 1.5–3 mm have been obtained. The developed SHS process does not create hazardous gases, and it takes ∼30 s for the ceramic phase formation. A high-level compaction due to centrifugal forces and a liquid phase sintering approach provided a dense gradient ceramic structure formed by oxide grains cemented by a glassy phase and bonded with a steel substrate through a thin iron layer. The coatings were successfully produced onto the inner surface of carbon and stainless steels’ tubes of up to 12 ft-lengths and standard dimensions from 2 to 3/8″ to 7.5” OD. The coatings were tested, for the first time, in wear and high-temperature corrosive environments, e.g., in steam–H2S–CO2 gases and molten salts, with encouraging results due to high contents of Al2O3 and some other oxides and consolidated ceramic structure. They can be recommended for applications in high-temperature (900 °C and greater) corrosive environments and erosive flows.

Study of the damping behaviour in samples consisting of iron electro-deposited on copper in an ionic liquid

Copper-iron alloys were produced at room temperature by means of electrodeposition of iron on a copper substrate in an ionic liquid (1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate [Py 1,4 ]TfO). Samples with different electrodeposition times were studied using mechanical spectroscopy, scanning electron microscopy, light microscopy and magnetic loops techniques. Independent of the electrodeposition time the electrodeposition process leads to the promotion of a thin layer of iron onto the copper surface without iron diffusion into the substrate. The damping spectra for electrosposited samples in the as-electrodeposited state show the characteristic low and intermediate grain boundary damping peaks from copper as well as the solvent grain boundary damping peak from the electrodeposited iron. Thermal annealing at temperatures near 973 K leads to the appearance of Fe particles at the interface between the copper and iron (Cu + α-Fe phase) leading to a new damping peak at around 680 K whose driving force is the diffusion of copper atoms around the second phase particles. • Iron-copper alloys produced by electrodeposition in an ionic liquid at room temperature. • Grain boundaries relaxation for the copper and iron in bi-layered alloys. • Damping peak related to the diffusion of copper atoms around the (alpha-Fe) particles.

Effect and mechanism of graphene structured palladized zero-valent iron nanocomposite (nZVI-Pd/NG) for water denitration

Nitrate reduction by zero-valent iron-based materials has been extensively studied. However, the aggregation of nanoparticles and the preference for unfavored ammonia products limit the application of this technology. To overcome this issue, this study introduced a novel synthesized nanoscale palladized zero-valent iron graphene composite (nZVI-Pd/NG) and explored its nitrate reduction efficiency. A nitrate removal rate of 97.0% was achieved after 120 min of reaction for an initial nitrate concentration of 100 mg N/L. The nitrogen gas selectivity was enhanced from 0.4% to 15.6% at the end point compared to nanoscale zero-valent iron (nZVI) particles under the same conditions. Further analyses revealed that zero-valent metal nanoparticles spread uniformly on the graphene surface, with a thin layer of iron (hydr)oxides dominated by magnetite. The nZVI-Pd/NG exhibited good catalytic activity with the associated activation energy of 17.6 kJ/mol being significantly lower than that with nZVI (42.8 kJ/mol). The acidic condition promoted a higher nZVI utilization rate, with the excess dosage of nZVI-Pd/NG ensuring a high nitrate removal rate for a wide pH range. This study demonstrates an improvement in nitrate reduction efficiency in a nZVI system by combining the exceptional properties of graphene and palladium.

Corrosion inhibition of iron surfaces with phosphatidic acid

Abstract Preventing the corrosion of iron in inaccessible structures requires a coating method that reaches all surface areas and creates a uniform protective layer. An ages old practice to protect iron artefacts is to coat them with animal fat, that is, a mixture of lipids. This “method” is accidentally ingenious: some natural phospholipids found in animal fat have the potential to form a tightly packed self-assembled monolayer on metal oxide surfaces, similar to the surfactant monolayers that have attracted increasing attention lately. Thus, the most primitive corrosion prevention method may point at a way to coat complex iron structures in an industrial environment. Here the ability of phosphatidic acid, a natural lipid, to coat and protect iron surfaces was examined. Iron coated quartz crystal microbalance (QCM) sensors were used for the experiments, to monitor the deposition of the lipid as well as the acidic corrosion (dissolution) of iron in situ, in real time. The sensors were coated by self-assembled monolayers of di-myristoyl phosphatidic acid using the liposome deposition method. In this process, 50-100 nm vesicles formed by the lipid are delivered in an aqueous solution and spontaneously coat the iron surfaces upon contact. QCM and ellipsometry measurements confirmed that continuous bilayer and monolayer surface coatings can be achieved by this method. QCM measurements also confirmed that the layers were corrosion resistant in 0.01M acetic acid solution that would dissolve the thin iron layer in minutes in the absence of the protective coating. XPS results suggested a chemisorption-based mechanism of phosphatidic acid attachment to the iron surface. Hence, liposome deposition of phosphatidic acid offers a suitable solution to coat iron surfaces in inaccessible structures in situ.

A PCB Sensor for Magnetic Materials

Printed circuit board (PCB) sensors are a sensor technology where the layout of traces on a PCB has been optimized so that the traces electromagnetically interact with the surrounding environment. These types of sensors can be manufactured at very low cost using standard commercially available low-cost printed circuit board fabrication. Exposed conductive electrodes on the circuit board are useful for measuring the electrical conductivity of the surrounding environment, and these sensors have been used in applications such as salinity measurement and dissolved ion content measurement of aqueous solutions. Insulated interdigitated electrode sensors are useful for capacitively analyzing the surrounding environment, and these sensors have been used to detect the presence of liquid water and to measure the moisture content of substances in physical contact with the sensor. Additionally, by measuring the complex impedance of the capacitive sensor over a wide frequency range, information concerning the chemical composition of the substance in contact with the sensor can be determined. In addition to conducive and capacitive PCB sensors, the third type of PCB sensor would be an inductive sensor. Although it is challenging to realize 3D coils in PCB technology, planar inductors can be realized in a single Cu layer on a PCB, and insulated from the environment using a cover layer of polymeric solder mask. This type of electrode structure can inductively couple with magnetic materials in close proximity to the sensor. A variety of magnetic materials exist, including iron, nickel and cobalt. Additionally, many alloys of these elements are also magnetic. Of particular interest are corrosion products with magnetic properties, such as iron(III) oxide, Fe3O2, also known as common rust. A thin layer of iron(III) oxide powder deposited on the sensor's active area results in a measureable increase in the sensor's inductance. As such, an inductive PCB sensor could be a low-cost option for detecting the presence of some corrosion products in its operating environment.

Enrichment of Precious Metals from Wastewater with Core-Shell Nanoparticles of Iron.

Large-scale deployment of zero-valent iron nanoparticles for enrichment and recovery of gold from industrial wastewater is reported. Iron nanoparticles have a core-shell structure in which a metallic iron core is enclosed with a thin layer of iron oxides/hydroxides. The two nanocomponents offer synergistic functions for rapid separation, enrichment, and stabilization of metal ions such as Au, Ag, Ni, and Cu. Thanks to the advantages of small size, large surface area, and high reactivity, only a small amount of iron nanoparticles are needed. The recovered nanoparticles thus contain precious metals well above conventional metal ores (e.g., >100 g Au ton-1 ). Cost-effective recovery of precious metals from trace-level sources such as wastewater looks promising.

Rock-art microbiome: influences on long term preservation of historic and culturally important engravings

The Burrup Peninsula in north-west Western Australia is home to one of the most substantial collections of rock engravings, or petroglyphs, in the world. These petroglyphs are carved through the dark coloured patina, commonly referred to as rock varnish, into the weathering rind of the local parent rock. Rock varnish is essentially a thin layer of manganese (Mn) and iron (Fe) oxides and hydroxides with embedded clay minerals, the formation of which is relatively poorly understood. It is generally considered to be a hostile environment for microorganisms due to extreme environmental conditions including low nutrient availability, lack of water, exposure to extreme ultraviolet radiation and intense seasonal and diurnal temperature fluctuations. However, despite these environmental extremes, microorganisms have been found on and in rock varnish and have been reported as playing a significant role in the formation of rock varnish. Given this, it is likely that any change in local environmental conditions will influence the types and activities of microorganisms found in and on rock varnish and associated rock art. This article focuses on the major influences on the microbiome of culturally important rock art in the Burrup Peninsula and the implications of any environmental change on the rock art itself.

Quantum optics with X-rays

The demonstration of strong coupling between two nuclear polariton modes in the X-ray spectral region using two coupled cavities each containing a thin layer of iron brings new opportunities for exploring quantum science.

Mechanism of Iron Oxide Scale Reduction in 5%H2–N2 Gas at 650–900 °C

The reduction behaviour of the oxide scale on hot-rolled, low-carbon steel strip in 5%H2–N2 gas at 650–900 °C was studied. In general, the reduction rate of the oxide scale at the centre location was more rapid than that at the near-edge location. In both cases, the reduction rates at 650 °C were extremely low and the rates increased with increased temperature, reaching their maxima at 850 °C. Arrhenius plot of the rate constant derived from the early parabolic stage revealed that the reduction mechanism at 650–750 °C differed from that at 750–850 °C, with the former being oxygen diffusion in α-Fe and the latter most likely iron diffusion in wustite. In all cases, a thin iron layer formed on the scale surface within a very short time and then the thickness of this layer remained essentially unchanged, while the scale layer was gradually reduced via outward migration of the inner wustite–steel interface, as a result of inward iron diffusion through the wustite layer to that interface. More rapid oxygen diffusion through the thin surface iron layer than the oxygen supply rate through interface reaction was believed to result in a lower oxygen potential at the outer iron–wustite interface, thus providing a driving force for iron to diffuse through the wustite layer. The inner wustite–iron interface became undulating initially; then with the rapid advance of some protruding sections, some parts of the wustite layer were reduced through first, and finally the remaining wustite islands were reduced to complete the reduction process. Porosities were generated when wustite islands were reduced due to localized volume shrinkage. Higher oxygen concentrations in the scales of the near-edge samples were believed to be responsible for their slower reduction rates than those of the centre location samples.

Mössbauer spectroscopy in determining the gas molecular state

A possibility of conversion electron Mossbauer spectroscopy for determining the gas molecular state is shown. For acceleration of gas interaction with active surface the thin iron layer enriched with 57Fe was applied on aluminum foil and gas discharge is used.

Feasibility of Carbon Nanofiber Catalyst Support for the Heterogeneous Fenton Process

AbstractThe heterogeneous Fenton oxidation reaction was investigated at two different catalytic supports including the blank alumina plates and alumina plates with thin carbon nanofiber (CNF) layer. Iron (III) oxide was used as a catalyst and propionic acid (PA) was studied as a model organic compound. A carbon nanofiber layer and a thin catalytic layer of iron (III) oxide were prepared using the chemical vapor deposition method with acetylene and ferrocene precursors. The reaction rate of heterogeneous Fenton oxidation was compared with the rate of homogeneous reaction. Obtained results indicate that the reaction rate is significantly higher at homogeneous Fenton oxidation at high temperature (70°C), however, the reaction rate for homogeneous and heterogeneous oxidation is comparable at room temperature (25°C) if carbon nanofiber support is used for the iron (III) oxide catalyst.

Diagnosis of energy transport in iron buried layer targets using an extreme ultraviolet laser

We demonstrate the use of extreme ultra-violet (EUV) laboratory lasers in probing energy transport in laser irradiated solid targets. EUV transmission through targets containing a thin layer of iron (50 nm) encased in plastic (CH) after irradiation by a short pulse (35 fs) laser focussed to irradiances 3 × 1016 Wcm−2 is measured. Heating of the iron layer gives rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9 nm laser radiation as the iron ionizes to Fe5+ and above where the ion ionisation energy is greater than the EUV probe photon energy (89 eV). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission (wavelength 13.9 nm) using IMP opacity values for the iron layer and the simulated transmissions are compared to measured transmission values. When a deliberate pre-pulse is used to preform an expanding plastic plasma, it is found that radiation is important in the heating of the iron layer while for pre-pulse free irradiation, radiation transport is not significant.

Broadband metallic absorber on a non-planar substrate.

Absorbers for visible and near-infrared light are realized by depositing a thin iron layer on arrays of cones which are replicated from a porous template. The replicated conic structure itself is of several micrometers and ineffective at antireflection, but the subsequent deposition of iron on top generates nano-meter-size columnar structures, and thus broadband absorption enhancement is achieved.

Growth of SiC NWs by vapor phase technique using Fe as catalyst

In this paper we report on the growth of silicon carbide nanowires deposited on silicon substrate with vapor phase technique at atmospheric pressure, using propane and silane as precursors and hydrogen as carrier gas.A thin layer of iron deposited on the silicon surface was used as catalyst.The morphology, crystal structure and details such as the growth direction of the as-prepared SiC NWs were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM).The SiC NWs have a diameter ranging from 30 to 100nm and length of tens of micrometers.XRD and High resolution TEM confirm the cubic structure of the nanowires and evidence a growth habit along the 〈111〉 direction.

Pulse plasma sintering of a tungsten/steel divertor module

The paper presents the preliminary evaluation of the potential of a pulse plasma sintering (PPS) technique for the fabrication of a He-cooled modular divertor with a multiple-jet cooling module. In this work the W and WL10 elements were directly bonded by PPS. Examination of the microstructure revealed some minor defects at the interface, but the overall quality of the joint was good with no cracks or delamination being detected. To reduce the thermal stress gradient a thin transition layer of iron was used at the WL10/steel interface. In addition an attempt was made to fabricate the complete module by a single sintering process. The microstructures of the fabricated modules were examined and the findings were reported.

The induction of nanographitic phase on Fe coated diamond films for the enhancement in electron field emission properties

A thin layer of iron coating and subsequent post-annealing (Fe-coating/post-annealing) is seen to significantly enhance the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films. The best EFE properties, with a turn on field (E0) of 1.98 V/μm and current density (Je) of 705 μA/cm2 at 7.5 V/μm, are obtained for the films, which were Fe-coated/post-annealed at 900 °C in H2 atmosphere. The mechanism behind the enhanced EFE properties of Fe coated/post-annealed UNCD films are explained by the microstructural analysis which shows formation of nanographitic phase surrounding the Fe (or Fe3C) nanoparticles. The role of the nanographitic phase in improving the emission sites of Fe coated/post-annealed UNCD films is clearly revealed by the current imaging tunneling spectroscopy (CITS) images. The CITS images clearly show significant increase in emission sites in Fe-coated/post-annealed UNCD films than the as-deposited one. Enhanced emission sites are mostly seen around the boundaries of the Fe (or Fe3C) nanoparticles which were formed due to the Fe-coating/post-annealing processes. Moreover, the Fe-coating/post-annealing processes enhance the EFE properties of UNCD films more than that on the microcrystalline diamond films. The authentic factor, resulting in such a phenomenon, is attributed to the unique granular structure of the UNCD films. The nano-sized and uniformly distributed grains of UNCD films, resulted in markedly smaller and densely populated Fe-clusters, which, in turn, induced more finer and higher populated nano-graphite clusters.

Surface and internal magnetic domain structures of Fe-Ga alloy rods

The magnetic domain structures of the 〈100〉 oriented Fe81Ga19 polycrystalline alloys with rapid quenching (RQ) and post-annealing (PA) thermal treatments are investigated by using magnetic force microscopy (MFM). The surfaces of the RQ alloy rods take on the dendritic domains after undergoing a standard mechanical polishing. While after PA processing, the distinct domain structures are observed at different temperatures. The wide stripe-like domain patterns appear in the surface of those PA rods at 550°C while the ramous domains remain at 400°C annealing. X-ray diffraction patterns indicate that a thin iron layer is formed on the surface of the specimens annealed at higher temperature. The soft magnetic iron layer, actually acting as a shield for the stray fields emerging from the internal magnetic structures underneath, brings about the presentation of the wide internal domains.

Energy transport in short-pulse-laser-heated targets measured using extreme ultraviolet laser backlighting

The accurate characterization of thermal electron transport and the determination of heating by suprathermal electrons in laser driven solid targets are both issues of great importance to the current experiments being performed at the National Ignition Facility, which aims to achieve thermonuclear fusion ignition using lasers. Ionization, induced by electronic heat conduction, can cause the opacity of a material to drop significantly once bound-free photoionization is no longer energetically possible. We show that this drop in opacity enables measurements of the transmission of extreme ultraviolet (EUV) laser pulses at 13.9 nm to act as a signature of the heating of thin (50 nm) iron layers with a 50-nm thick parylene-N (CH) overlay irradiated by 35-fs pulses at irradiance 3×10(16) Wcm(-2). Comparing EUV transmission measurements at different times after irradiation to fluid code simulations shows that the target is instantaneously heated by hot electrons (with approximately 10% of the laser energy), followed by thermal conduction with a flux limiter of ≈0.05.

Heterogeneous formation of ferric oxide nanoparticles on chlorite surfaces studied by x-ray absorption spectromicroscopy (STXM)

The homogeneous and heterogeneous formation of ferric iron oxides from acidic solution (pH 2.06–2.50) has been studied in the presence of chlorite under constant pH conditions using titration experiments. Significantly shorter induction times for the ferrihydrite formation have been macroscopically observed in the presence of chlorite particles, thus indicating heterogeneous nucleation as a major precipitation mechanism. A combination of Scanning Electron Microscopy (SEM) and Scanning Transmission X-Ray microscopy (STXM) on the O K-edge and Fe L-edge was used to clearly distinguish ferric iron precipitates from chlorite and to obtain the spatial distribution of iron precipitates on the chlorite surface under conditions of homogenous and heterogeneous formation.Oxygen K-edge results show the precipitation of a highly hydrolyzed chlorite surface associated ferric iron phase under heterogeneous conditions. Precipitates with different oxygen K-edge features are observed on the chlorite basal faces compared to the edge surfaces which can be attributed to cluster size effects and differences in the O/OH ratio. The results obtained from iron L-edge XANES corroborate the observations of the oxygen K-edge, indicating a thin surface layer of ferric iron precipitates and preferential precipitation at the chlorite edge surfaces. Under conditions where homogeneous ferrihydrite formation dominates, beside surface coatings separate iron colloids/nanoparticles are observed. Iron L-edge analysis and the pre-edge splitting on the oxygen K-edge indicate a higher long-range order/lower hydration comparable to ferrihydrite reference spectra. The results show that the Fe(III) secondary phase formation as surface coating or nanoparticles and their spatial distribution depends on the degree of supersaturation. These observations may have direct consequences for the retention and mobility of various contaminants in aquifer systems and potential remediation strategies.

Structural and electronic properties of Fe3O4/graphene/Ni(111) junctions

AbstractThe Fe3O4(111)/graphene/Ni(111) trilayer is proposed to be used as an ideal spin‐filtering sandwich where the half‐metallic properties of magnetite are used. Thin magnetite layers on graphene/Ni(111) were prepared via successive oxidation of a thin iron layer predeposited on graphene/Ni(111) and the formed system was investigated by means of low‐energy electron diffraction and photoelectron spectroscopy. The electronic structure and structural quality of the graphene film sandwiched between two ferromagnetic layers remain unchanged upon magnetite formation as confirmed by experimental data.magnified imagePreparation of the HMF/graphene/FM junction.(© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)