Iron Substrate Research Articles

Boosting nitrogen removal efficiency of wastewater treatment plant tailwater through iron-rich tidal flow constructed wetland: Insights on the microbial removal mechanism

Iron-rich tidal flow constructed wetlands (ITCW) have emerged as effective and eco-friendly systems for achieving high-efficiency total nitrogen (TN) removal in tailwater. However, the microbial removal mechanism in ITCW, particularly the microbial assembly processes, remains unclear, which limits understanding of the relationship between micro-level microbial activities and macro-level performance of ITCW. In this study, ITCW was constructed to investigate its performance, microbial responses, and community assembly mechanisms using metagenomics and the neutral community model (NCM). Results demonstrated that total nitrogen removal in ITCW increased by 52.53 ± 9.03 % and 21.20 ± 6.26 %, respectively, compared to conventional constructed wetlands and iron-based constructed wetlands. The combination of tidal flow and iron substrate established an active iron cycle in ITCW. The iron cycle improved electron transfer capacity and supported the enrichment of nitrifiers (e.g., Nitrospira) and denitrifiers (e.g., Hydrogenophaga, Thauera), enhancing nitrogen removal efficiency in ITCW. Metagenomic analysis confirmed an increased relative abundance of functional genes associated with nitrogen metabolism (e.g., amoA, nirSKABD) and the iron cycle (e.g., korB). NCM analysis indicated that stochastic processes influenced community assembly in all three CWs. Nonetheless, tidal flow operations in ITCW reduced stochastic influences, fostering niche specialization of functional nitrogen microorganisms, which supported their growth while minimizing functional redundancy, thereby enhancing nitrogen treatment performance. These findings offer significant insights into microbial mechanisms for nitrogen removal and provide theoretical guidance for ITCW design and operation.

Microstructure and wear characteristics of austenitic stainless steel coatings fabricated through various directed energy deposition

Austenitic stainless steels are widely used in automotive and marine environments because of their high toughness, corrosion resistance, and wear resistance. The present comparative study focuses on the microstructure and wear resistance of double-layer austenitic stainless-steel coatings prepared on a ductile iron substrate using circular spot high-speed laser-directed energy deposition (DED) and broad-beam laser-DED. The results indicate that while the deposition process does not alter the physical phase of coating, it does influence the preferred orientation of surface grains. Both coatings exhibit characteristics of hypoeutectic alloys, where the harder eutectic structure serves as a skeleton to resist external pressure. The high-speed laser-DED coating demonstrates higher hardness and wears resistance due to its denser eutectic structure. In addition, its finer microstructure produces smaller wear debris, contributing to the formation of a denser oxide film, thereby enhancing wear resistance.

Tribomechanical characterization of ceramic reinforced composite coatings for modification of cylinder liner of heavy-duty diesel engines

Heavy-duty diesel engines are essential mechanic power generation tools for industry and transporting freight and passengers. Therefore, increasing engine efficiency and minimizing maintenance and repair costs is crucial. This study examines and characterizes three thermal spray coatings (Cr3C2/NiCr, NiCr, and Al2O3/TiO2) utilized on cylindrical gray cast iron substrate specimens. The coatings were tested for their microstructural (optical microstructure, SEM, EDS, XRD, and AFM topography), mechanical (nanoindentation and nano scratch), and tribological (short and long-distance wear test) properties. Microstructural tests showed that an average coating thickness of 120 to 170 µm was successfully achieved on the cast iron base substrate using different thermal coating methods. The Cr3C2/NiCr coating, observed through the AFM mapping method, achieved the most uniform roughness distribution on the surface. The elasticity of the coatings was measured with a nanoindentation test, and Al2O3/TiO2 coating exhibited high rigidness (177 GPa). The nano scratch test showed that the highest load-carrying capacity was achieved with the Cr3C2/NiCr coated sample. NiCr-coated sample exhibited approximately similar rigidness (61 GPa) to cast iron (67 GPa). Short- and long-distance wear tests showed that the coatings provided significantly better wear resistance than the cast iron base. The coatings’ efficacy was evident. At the long-distance tests, while the cast iron base sample had a wear rate of 19.874 (10−7mm3/Nm), the wear rates of Al2O3/TiO2, Cr3C2/NiCr, and NiCr coatings were 3.835, 4.020, and 6.466 (10−7mm3/Nm), respectively. The Al2O3/TiO2 and Cr3C2/NiCr coatings had superior tribological performance than the NiCr coating, yet the NiCr coating showed much higher wear performance than the uncoated base. The Cr3C2/NiCr coating exhibited superior tribomechanical performance in all the coatings.

Electrical and Magnetic Properties of Rough Alloyed Interface of Fe/Co.

We investigated the electronic structure of rough interfaces in random Co/Fe  alloys, where cobalt (Co) was deposited on an iron (Fe) substrate with varying composition ratios. To model the rough surface, we utilized a coupled continuum equation as described by Huda. The electronic properties, specifically the density of states of these random alloys, were calculated using the augmented space recursion method in conjunction with the Linear Muffin-tin Orbital (LMTO) Method. Furthermore, we analyzed the magnetic and electronic properties derived from the calculated density of states.

Determination of saturated dissolved oxygen concentration in iron sulfate solutions containing iron oxidizing microorganisms

Iron sulfate solutions and the extremophile lifeforms that can live within them are industrially and environmentally important in many applications and require proper assessments of solution properties. Determination of saturated dissolved oxygen concentration is an important parameter for monitoring iron biooxidation processes. However, its determination is not so straight forward using commercially available dissolved oxygen meters. Such meters utilize internal calculation models based on the saline properties of seawater which can be easily overlooked. A method for determination of the saturated dissolved oxygen concentration in acidic iron sulfate solutions with the inclusion of other inorganic salts is proposed in this work using the biooxidation of ferrous iron as an indicator measured with redox potential and converted to oxygen concentration through bioreaction stoichiometry. The technique was tested on a BioGenerator system over the course of four days and proved satisfactory in establishing a value for the saturated dissolved oxygen concentration of the bioreactor broth. Study of the lifespan properties of the microorganisms in absence of ferrous iron substrate was briefly examined to determine the effective handling period of solutions for assessment.

High-temperature tribological evaluation of cobalt-based laser cladded disc for automotive brake systems

This study investigates the high-temperature wear behavior of laser-cladded (LC) cobalt-based Stellite 6 alloy coatings and compares the wear resistance of the cladding layer to the grey cast iron (GCI) substrate material at three different elevated temperatures: 150 °C, 250 °C, and 350 °C. Wear mechanisms at elevated temperatures were analyzed using SEM-EDS and Raman Spectroscopy to understand the material removal processes and degradation for the discs and counterpart composite friction material pins, respectively.The results indicated a significant improvement in wear resistance for cobalt-based alloy cladding at high temperatures. Wear rates were reduced by 5.0 %, 43.0 %, and 16.0 % at 150 °C, 250 °C, and 350 °C, respectively. The LC - brake pin tribo-pair exhibited a continuous increase in friction coefficients (CoF) with an increase in testing temperatures. The wear mechanism for laser-cladded discs exhibited a combination of abrasive and adhesive wear, with abrasive wear prevailing at 150 °C and increased adhesive wear at 250 °C and 350 °C. However, at 350 °C, decomposition of phenolic resin and the adhesive wear mechanism, led to brake pin failure. For GCI discs oxidative wear was identified as the predominant wear mechanism. The improved knowledge of wear mechanisms on LC Stellite 6 against composite brake pins, is set to enhance surface modification of GCI for brake disc applications.

Enhanced erosion-corrosion resistance of monolithic ENP coating on ductile cast iron by using electrochemical pretreatment and heat treatment

This research aims to enhance the erosion-corrosion durability of monolithic ENP coating used on ductile cast iron. The ENP coating does not usually adhere well to the cast iron surface due to the special characteristics and innertness of the graphite sphere so an electrochemical surface pre-treatment containing a cathodic treatment was implemented to ensure proper adhesion of the coating to the surface. A slurry pot erosion-corrosion test was performed at a linear velocity of 10 m/s for 16 h, and it verified the efficacy of the treatment. Three different heat treatments were carried out on coated samples at 200 °C, 400 °C, and 600 °C. The sample heat-treated at 600 °C exhibited a pseudo-passivation behavior and displayed the best corrosion resistance of 0.1407 μA/cm2. Nonetheless, in erosion-corrosion tests, it was outperformed by other coatings due to the removal of its oxide layer. The heat treatment at 400 °C resulted in the highest hardness of 871 Vickeres and the best erosion-corrosion resistance of 8.8 mpy compared to 11.74 mpy for the as-plated sample and 381.3 mpy for the cast iron substrate.

Friction Mechanism of Sulfur-Containing Lubricant Additives Confined between Fe(100) Substrates.

Sulfur-containing lubricant additives can chemically react with metal surfaces under extreme conditions, such as high temperature and high pressure, forming protective films on the surfaces. However, the formation mechanisms and the friction-reducing and antiwear properties of these films remain unclear. In this study, we investigated the friction process of sulfur-containing additives confined between two iron surfaces using reactive molecular dynamics simulations. Our research revealed that in systems with a higher S/C ratio, an iron sulfide layer formed on the iron surfaces with Fe-S-Fe bridging bonds at the interface, resulting in relatively smaller friction and wear even under higher loads. However, in systems with lower S/C ratios, the presence of numerous interfacial Fe-Cn-Fe bridging bonds, caused by the hydrocarbon radicals released from the additives, led to the formation of thick amorphous shearing bands at the interface between the two substrates. In this case, the distributed sulfur atoms also exhibited some effect in reducing the shear resistance of the amorphous shearing bands due to the weak strength of S-Fe bonds compared to the strength of C-Fe bonds. These atomic-level insights help understand the antiwear characteristics of sulfur-containing lubricant additives confined between iron substrates.

Thermal cycle behaviour of plasma sprayed thermal barrier coatings on cast iron substrate for the application of liner of internal combustion engine

In the present scenario, research on Thermal Barrier Coatings (TBCs) is attracting significant attention in high-temperature applications due to the rising demand in industrial applications, such as gas turbine blades and internal combustion engine components. To meet these demands, it is essential to enhance the mechanical and oxidation properties of thermal barrier coatings. The atmospheric plasma spray methodology for producing these coatings has become a central focus in recent times. In this work, TBCs were prepared by blending pure alumina and Yttria-Stabilized Zirconia (YSZ) in equal proportions. Extensive study of TBCs carried out under high-temperature conditions through thermal cycle tests at elevated temperatures, around 850 °C. A total of 350 thermal cycles were conducted, and microstructures of the coating surface were examined at 150, 250, and 350 cycles. High-temperature stress, generated due to the sintering of the coating, also influences the life of the coatings. Specimen with a topcoat thickness of 300 μm, exhibited good thermal shock resistance compared to the specimens with topcoats of thickness of 100 μm and 200 μm. The effects of process parameters, porosity, and thermal shock resistance are presented in detail. The topcoat with a thickness of 300 μm demonstrated excellent thermal shock resistance and reduced formation of thermally grown oxide (TGO). The porosity of the coating, found to be between 2% and 3%, contributed to its dense nature, effectively reducing oxidation rates and enhancing the coating's lifespan under cyclic high-temperature conditions.

XPS study of electroless NiP coating on iron substrate

XPS study of electroless NiP coating on iron substrate

Thermal analysis of laser fabricated new composite brake drums in each orientation

In this study, a Fe-based alloy material was fabricated by laser on the inner shell of a brake drum. The thermal conductivity of the composite brake drum was analyzed and discussed by conducting experiments on the shell nodular cast iron substrate, laser manufacturing materials, and their composites, as well as different heat transfer directions of laser manufacturing materials. At 500 °C, the thermal conductivity of the matrix was 21.434 W/(m·K), the Fe-base alloy was 15.271 W/(m·K), and the composite sample was 17.442 W/(m·K), which was close to the average value of the two. The grain characteristics and microstructure of the alloy were different in different directions. The thermal conductivities of the samples in the x-, y-, and z-directions were 17.047 W/(m·K), 16.665 W/(m·K), and 15.271 W/(m·K), respectively; the diffusion was slower in the z direction and fastest in the x direction.

A Low-Cost Iron-Based Substrate for Alkaline Battery Electrodes

The nickel foam current collector adds significantly to the cost of the positive electrode of nickel-based alkaline batteries.1 Iron is roughly 40 times less expensive than nickel; but iron corrodes at the operating potential of the nickel electrode at pH 14 or higher.2 Thus, for an iron substrate to be viable, it should be protected from anodic corrosion in alkali and the surface must be electrically conducting. We found that a 100 nm thick thermal coating of cobalt ferrite protects iron from corrosion. The protected iron substrate was stable for 1000 h even when anodically polarized at 10 mA cm−2 in 30% potassium hydroxide battery electrolyte.3 The electrical conductivity of the coating could be improved by the incorporation of lithium-ions. The enhanced conductivity was attributed to an increase in the population of Co3+ in the spinel lattice as evidenced from XPS and XAS analyses.4 The nickel electrode on such an inexpensive iron-based substrate exhibited a specific capacity of 0.25 Ah g−1 at C/5 discharge rate, comparable to a nickel hydroxide electrode on expensive nickel foam. The electrode also exhibited no noticeable degradation for 150 cycles at C/2 rate. This robust and economical iron substrate thus presents a unique opportunity for reducing the cost of the nickel electrode in aqueous alkaline batteries.

Characterization of Iron Oxide Nanotubes Obtained by Anodic Oxidation for Biomedical Applications-In Vitro Studies.

To improve the biocompatibility and bioactivity of biodegradable iron-based materials, nanostructured surfaces formed by metal oxides offer a promising strategy for surface functionalization. To explore this potential, iron oxide nanotubes were synthesized on pure iron (Fe) using an anodic oxidation process (50 V-30 min, using an ethylene glycol solution containing 0.3% NH4F and 3% H2O, at a speed of 100 rpm). A nanotube layer composed mainly of α-Fe2O3 with diameters between 60 and 70 nm was obtained. The effect of the Fe-oxide nanotube layer on cell viability and morphology was evaluated by in vitro studies using a human osteosarcoma cell line (SaOs-2 cells). The results showed that the presence of this layer did not harm the viability or morphology of the cells. Furthermore, cells cultured on anodized surfaces showed higher metabolic activity than those on non-anodized surfaces. This research suggests that growing a layer of Fe oxide nanotubes on pure Fe is a promising method for functionalizing and improving the cytocompatibility of iron substrates. This opens up new opportunities for biomedical applications, including the development of cardiovascular stents or osteosynthesis implants.

Microstructure, mechanical and electrochemical behavior of magnetron-sputtered carbothermic reduced iron-boride ceramic coatings

In this study, magnetron sputtered carbothermic reduced iron boride (FeB) coatings were developed on grey cast iron (GCI) substrates at different substrate temperatures. The impact of substrate temperature on structural, mechanical, and corrosion behavior was examined for two FeB deposition scenarios: FeB coatings deposited at room temperature (RT) and at 500 °C substrate temperature. The evolution of phases and microstructure was studied using XRD and FESEM, respectively. The mechanical properties, creep, deformation behavior, and adhesion strength (scratch test) of the deposited coatings were investigated using nanoindentation at ambient temperature. The highest hardness and Young’s modulus of 16 GPa and 231 GPa respectively, were achieved at 500 °C due to microstructural enhancement. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behavior of the coatings. The results show that substrate temperature strongly influences the surface morphology of the coatings, which in turn governs the mechanical and corrosion behavior of the FeB coating. The FeB-coated GCI at 500 °C substrate temperature showed higher resistance to scratching, better mechanical properties, and improved corrosion resistance which is attributed to the enhanced adhesive strength, refined microstructure, and formation of protective oxide layers of FeB on the surface of the coatings.

Corrosion resistance of zinc-magnesium-aluminium alloy coated steel in marine atmospheric environments

In this study, a salt-spray accelerated experiment was conducted as a simulated corrosion test of hot-dip galvanised zinc-magnesium-aluminium-coated alloy steel under a simulated marine atmospheric environment. In addition, scanning electron microscopy, confocal microscopy, X-ray diffraction, and electrochemical workstations were used to conduct analyses on the macro-morphology, microstructure, corrosion product composition, etc. after the corrosion test. Furthermore, the role of Mg in the corrosion resistance of zinc-magnesium-aluminium alloy steel sheets was determined. The research results indicated that in a marine atmospheric environment, zinc-aluminium-magnesium alloy steel has excellent corrosion resistance, and its external coating provides protection to the substrate. In a marine atmospheric environment, the corrosion products of zinc-magnesium-aluminium alloy steel mainly include Al2O3, AlOOH, zinc hydroxychloride (Zn5(OH)8Cl2·H2O), layered bimetallic hydroxides (Mg6Al2(OH)16CO3·4H2O), ZnO, and MgCO3·H2O. The addition of magnesium to galvanised sheets facilitates the formation of insoluble corrosion products, which protect the iron substrate.

Study of the process parameters influence on crack formation in laser alloying of grey cast iron

This study aimed to investigate the influence of process parameters on crack formation in laser alloying or cladding of grey cast iron. For this purpose, the effects of laser power and feeding rate of Ni-based alloying powders were examined. The microstructure and hardness of the coating and the interface of the coating with cast iron (bonding zone) were studied. The results showed that the dilution ratio is crucial in crack formation, explaining the challenges in achieving a defect-free laser alloying coating on cast iron. The higher dilution ratio of laser alloying resulted in higher dissolved carbon and bigger (Nb, Ti)C carbides formation than in laser cladding coatings. In this study, cracks appeared in the coating due to the combination of the high amount of carbide in the layer and a sharp hardness gradient at the interface with the cast iron substrate. An empirical relation was proposed for dilution ratio as a function of specific energy density, which combined the most critical process parameters on crack formation.

Kinetic Study of Anaerobic Adhesive Curing on Copper and Iron Base Substrates.

Anaerobic adhesives (AAs) cure at room temperature in oxygen-deprived spaces between metal substrates. The curing process is significantly influenced by the type of metal ions present. This study investigates the curing kinetics of a high-strength AA on iron and copper substrates using differential scanning calorimetry (DSC). The activation energy and kinetic parameters were determined with different empiric models, revealing that curing on copper is faster and more complete compared to iron. The findings suggest that copper ions lower the activation energy required for curing, enhancing the adhesive's performance. This research addresses the gap in understanding how metal ions affect AA curing kinetics, offering valuable insights for optimizing adhesive formulations for industrial applications.

An α-ketoglutarate conformational switch controls iron accessibility, activation, and substrate selection of the human FTO protein

The fat mass and obesity-associated fatso (FTO) protein is a member of the Alkb family of dioxygenases and catalyzes oxidative demethylation of N6-methyladenosine (m6A), N1-methyladenosine (m1A), 3-methylthymine (m3T), and 3-methyluracil (m3U) in single-stranded nucleic acids. It is well established that the catalytic activity of FTO proceeds via two coupled reactions. The first reaction involves decarboxylation of alpha-ketoglutarate (αKG) and formation of an oxyferryl species. In the second reaction, the oxyferryl intermediate oxidizes the methylated nucleic acid to reestablish Fe(II) and the canonical base. However, it remains unclear how binding of the nucleic acid activates the αKG decarboxylation reaction and why FTO demethylates different methyl modifications at different rates. Here, we investigate the interaction of FTO with 5-mer DNA oligos incorporating the m6A, m1A, or m3T modifications using solution NMR, molecular dynamics (MD) simulations, and enzymatic assays. We show that binding of the nucleic acid to FTO activates a two-state conformational equilibrium in the αKG cosubstrate that modulates the O2 accessibility of the Fe(II) catalyst. Notably, the substrates that provide better stabilization to the αKG conformation in which Fe(II) is exposed to O2 are demethylated more efficiently by FTO. These results indicate that i) binding of the methylated nucleic acid is required to expose the catalytic metal to O2 and activate the αKG decarboxylation reaction, and ii) the measured turnover of the demethylation reaction (which is an ensemble average over the entire sample) depends on the ability of the methylated base to favor the Fe(II) state accessible to O2.

The decoration of NiFe layered-double-hydroxide/NiFe nanoalloy grown in a corrosion-cell by MoS2 nanosheets as a binder-free electrode for efficient overall water splitting

Nickel-Iron layered double hydroxides (NiFe-LDH) prepared by corrosion engineering has been proven effective for electrochemical overall water splitting, but the growth mechanism is still controversial. In this work, nano-Fe (0) powder was used as the iron substrate to produce NiFe nanoalloy under corrosion conditions as the corrosion-cell cathode, and then NiFe-LDH nanosheets were deposited. The NiFe-LDH/NiFe nanoalloy particles were captured on carbon cloth by a "network" structure by interlacing MoS2 layers, creating a binder-free self-supporting electrode (MoS2/NiFe-LDH/NF-NP/CC). The MoS2/NiFe-LDH/NF-NP/CC exhibited excellent overall water splitting performance, with a current density of 10 mA cm−2 at a voltage of only 1.52 V, owing to the abundant HER active sites at the edge of MoS2 nanosheets, the high conductivity and OER properties of the NiFe-LDH/NiFe nanoalloy, as well as the effective 3D heterojunction structure.

Ab initio informed machine learning potential for tribochemistry and mechanochemistry: Application for eco–friendly gallate lubricant additive

Mechanochemistry and tribochemistry processes involve multiple physical/chemical interactions induced by extreme conditions including molecular confinement, high temperatures and mechanical stress applied. Simulating these processes by molecular dynamics is very challenging. While force fields fall short reproducing the enhanced reactivity arising by quantum effects, ab initio molecular dynamics is severely limited by the complexity of the systems of interest, their sizes, and the long-time scale on which relevant events take place. In this work using an active learning approach, a landmark deep neural network potential has been developed which reproduces the accuracy of ab initio interactions at the classical molecular dynamics computational cost and permits to successfully simulate the tribochemical processes occurring at the interface between butyl gallate molecules and iron substrates under tribological conditions. The simulations of the dynamics of the Fe-gallate system when sliding under an imposed external load reveal the key atomistic mechanisms underlying the formation of the friction reducing lubricant tribofilm and permit to characterize the tribological properties of the explored systems, clearly exposing the shortcoming of reactive force field based approaches. The successful development of neural network potentials, making it possible to push the limits of molecular dynamics marrying accuracy with system sizes and long time scales, paves the route toward a new area in computational tribochemistry.