Iron Surface Research Articles

Characteristic analysis of s-Fe/Cu two-component micro-electrolysis materials and degradation of dye wastewater.

Micro-electrolysis is a pretreatment technology for difficult-to-biodegrade wastewater. In this study, a chemical displacement method was used to load copper on the surface of sponge iron (s-Fe), and then it was mixed with activated carbon and other components to obtain a multi-element micro-electrolytic filler (OMEF). Through BET, SEM, XRD, XPS, and FT-IR characterization and analysis, OMEF was proved to have a specific surface area of 88.374 m2/g, C-C, C-O, C = O, O-C = O, and other functional groups and Fe3C, MnO2 and other active materials. The removal mechanism of organic pollutants in wastewater by OMEF could be due to the galvanic reaction, direct reduction of Fe, oxidation of Fe, catalytic oxidation of Cu and Mn, and co-precipitation of adsorption. The coupling of the micro-electrolysis and biological methods proved that OMEF had excellent application efficiency. The results indicated that the COD removal rates of OMEF and commercial fillers reached 88.39% and 48.02%, respectively, and the B/C reached 0.74 and 0.3. OMEF showed a better performance. The reusability of the OMEF filler was measured to ensure that the B/C was maintained at around 0.5 during 5 cycles. Kinetic analysis showed that the degradation data of methyl orange (MO) and the removal data of COD obeyed pseudo-second-order kinetics. Moreover, it can further broaden the pH range of treated wastewater and increase the oxidation rate. This new strategy has brought potential enlightenment for the development of high-efficiency wastewater pretreatment using new micro-electrolysis materials. The excellent performance of OMEF micro-electrolytic filler in pretreatment indicated its potential for industrial application.

Facile Approach for Omniphobic and Anti-icing on Fe Surface

The functionalized process refers to a new concept, which aims to modify the physical and chemical properties of the original surface for specific purposes. Hence, the functional surfaces will introduce the desired properties that can not be found in the original material. The various applications might be named liquid repellent, anti-icing, anti-reflection, water harvesting, anti-biofouling, etc. This study proposes a simple and fast fabrication method based on etching incorporated with low surface energy chemical compound coating to functionalize the Iron (Fe) surface for omniphobic and anti-icing characteristics. After being functionalized, the surface reveals an omniphobic state with various liquids and extremely low adhesion to ice bulk. The research might suggest solutions for manufacturing functional surfaces oriented to outdoor applications such as windshields, rearview mirrors, anti-fouling surfaces, etc

Effects of honing process parameters on residual stress fields of grey cast iron engine cylinder liners: Experimental and numerical study

Super polishing methods are widely employed to improve the surface integrity of machined parts. These methods not only improve the surface texture of the machined parts, but also modify the residual stresses induced at the outer layer of the machined surface. In this study, the effects of honing process parameters on the distribution of residual stresses at the surface of grey cast iron investigated numerically and experimentally. To this aim, a finite element (FE) model developed to evaluate the effects of process parameters, including cutting speed, grain size, and pressure of honing tools, on the residual stresses induced at the surface of samples. The friction coefficient introduced as an updating parameter in the model to get the best correlation between the results of FE and experiments. In addition, the X-ray diffraction method used to experimentally measuring the distribution of residual stresses at the honing surface of the samples. The experimental and numerical results showed that in majority of combinations of the process parameters, the maximum compressive residual stress occurs at a depth of approximately 0.03 mm from the cutting surface of the sample. Additionally, it was seen that decreasing the size of abrasive grains and cutting speed and increasing the pressure on the cutting tool result in higher levels of induced compressional stresses at the surface of samples. However, the depth at which the maximum residual stress occurs can proceed up to 0.06 mm by an increase in the diameter of abrasive grains and cutting speed.

Multiwall Carbon Nanotubes for Solid Lubrication of Highly Loaded Contacts

When lubrication of rolling bearings with oil or grease is not possible, for example because the lubricant evaporates in vacuum, solid lubrication by multiwall carbon nanotubes (MWCNT) is a viable alternative. To understand the mechanisms underlying MWCNT lubrication of highly loaded contacts, we combine an experimental approach with large-scale molecular dynamics (MD) simulations. Tribometry is performed on ground iron plates coated with two different types of MWCNTs by electrophoretic deposition. Although structural differences in the MWCNT materials result in slightly different running-in behavior, most of the tests converge to a steady-state coefficient of friction of 0.18. The resulting wear tracks and tribolayers are subjected to structural and chemical characterization and suggest a tribo-induced phase transformation resulting in tribolayers that consist of MWCNT fragments, iron oxide, and iron carbide nanoparticles embedded in an amorphous carbon matrix. Covalent bonding of the tribolayer to the iron surface and low carbon transfer to the alumina counter body indicate sliding at the tribolayer/ball interface as the dominant mechanism underlying MWCNT solid lubrication. MD simulations of nascent a-C tribofilms lubricated by MWCNT bundles and stacks of crossed MWCNTs reveal two different sliding regimes: a low-load regime that leaves the MWCNTs intact and a high-load regime with partial collapse of the tube structure and formation of a-C regions. The critical load for this transition increases with the filling ratio of the MWCNT and the packing density of the stacks. The former determines the stability of the MWCNT, while the latter controls the local stresses at the MWCNT crossings. For both MWCNT materials, the high-load regime is predicted for the experimental loads. This is confirmed by a remarkable agreement between transmission electron microscopy (TEM) and atomistic simulation images. Based on the findings of this work, a multistep lubrication mechanism is formulated for MWCNT coatings rubbing against alumina on an iron substrate.

A detailed experimental performance of 4-quinolone derivatives as corrosion inhibitors for mild steel in acid media combined with first-principles DFT simulations of bond breaking upon adsorption

Four 4-oxo-1,4-dihydroquinoline-3-carboxylate derivatives were synthesized through the Gould-Jacobs method and evaluated as corrosion inhibitors for 1020 mild steel in 1 mol/L hydrochloric acid. Gravimetric experiments showed that those organic molecules present 84–94 % anticorrosive efficiency at 2.00 mmol/L (298 K). At higher temperatures (318 and 338 K), those values go up to 97.3 % for the methoxy-substituted compound. Electrochemical measurements depicted that the charge-transfer mechanism controlled the corrosive and inhibitive processes and that the presence of the four organic substances in the electrolyte enhanced the polarization resistance and significantly diminished the corrosion density current, acting by adsorption on the metal surface. Polarization curves confirmed that they all are mixed-type corrosion inhibitors. Atomic Force Microscopy illustrated the topography of the metallic surface and suggested to the formation of a protective layer. Atomistic simulations by first-principles Density Functional Theory revealed the formation of covalent bonds between quinolone molecules and the iron surface, with MODC and AODC having the stronger negative interaction energy values compared to NODC and CODC compounds. Electronic analysis of the adsorption geometries of molecules at Fe(110) indicated that chemical coordination is a result of strong charge transfer and charge rearrangement upon adsorption.

Development of an intervention program to reduce whole-body vibration exposure based on occupational and individual determinants among dumper operators

ABSTRACT Objectives. Studies related to a systematic approach for intervention design to reduce whole-body vibration (WBV) exposure are scarce. This study presents a systematic approach to identifying, selecting and prioritizing safety interventions to fulfill that research gap. Methods. A total of 130 vibration readings for dumper operators were taken from two surface iron ore mines to identify significant determinants of WBV exposure. Initially, age, weight, seat design, awkward posture, machine’s age, load tonnage, dumper speed and haul road condition were hypothesized as determinants. Data were collected through standardized questionnaires and field-based observation. A multivariate statistical approach was applied for the practical use of the intervention program. Results. As some of the hypothesized factors were correlated, exploratory factor analysis (EFA) followed by multiple linear regression (MLR) was used to investigate their association with WBV exposure. As per EFA results, hypothesized factors were clubbed under individual, ergonomics and occupational factors. Occupational and ergonomics factors were found to be significantly associated with WBV exposure through MLR and used to form safety interventions to reduce WBV exposure. Conclusions. Our methodological approach is original in the occupational health research area and can be helpful to tailor the safety interventions for the unit level with minimum effort.

The Stability of the Layer Nitrided in Low-Pressure Nitriding Process

The kinetics of the nitrided layer thickness growth and its structure depend on the nitrogen flux from the atmosphere to the nitrided surface. A nitrogen flux to the surface is more significant than a diffusion flux into the substrate, during forming surface iron nitrides and the internal nitriding zone. For pure iron, nitrided under low pressure, cutting off the nitriding atmosphere creates a flux from the subsurface layer of nitrides to the surface. The purpose of this paper is to determine the direction of the nitrogen flux in a similar situation for steels containing nitride-forming elements, thus answering the question of the stability of the layer nitrided under such conditions. The surface of X37CrMoV5-1 steel was nitrided under low pressure (of 24 hPa) and annealed in a vacuum or nitrogen. The microstructure, thickness of the nitride layers nitrided layers, the thickness of the internal nitriding zone, surface hardness and stresses were examined. The highest values of the nitrided layer properties were observed for the samples saturated only with nitrogen obtained from ammonia dissociation or additionally heated in nitrogen. It has been shown that using a pure vacuum during the annealing stage leads to unfavourable changes in the structure of the nitrided layer formed and, in particular, to the decomposition of the iron nitride layer formed at the saturation stage and occurrence of the tensile stresses—what excludes practical application of such layer. Ultimately, it has been shown that in the low-pressure nitriding process, the stability of the nitride layer of the nitrided surface strongly depends on the annealing atmosphere during the annealing stage, while the stability of the internal nitriding zone remains mainly at the same level.

Regulating the reaction pathway of nZVI to improve the decontamination performance through magnetic spatial confinement effect

Nanoscale zero-valent iron (nZVI) shows high effectiveness in the catalyzed removal of contaminants in wastewater treatment. However, the uncontrolled interfacial electron transfer behavior and formation of surface iron oxide (FeOx) layer led to severe electron wasting and occasionally form highly toxic intermediates. Here, we constructed magnetic mesoporous SiO2 shell on surface of nZVI to stimulate a magnetic spatial confinement effect and regulate the electron transfer pattern. Therein, Fe atom facilely spread out from the nZVI core, orderly release electron to surface adsorbed H2O molecule, which is efficiently transformed into active hydrogen (H*). Meanwhile, in-situ Raman revealed that Fe atoms were involved in the formation of penetrable γ-FeOOH rather than FeOx layer, enabling the continuous inward diffusion of H2O and outward diffusion of H* . Employing the catalyzed removal of halogenated phenols as demo reaction, the presence of magnetic mesoporous SiO2 shell utilized the reaction between electrons and H2O to switch the reaction pathway from the reduction/oxidation hybrid process to hydrodehalogantion, and increased the conversion of halogenated phenols-to-phenols by 5.53 times. This study shows the forehand of improving the decontamination performance of nZVI through sophisticated designed surface coating, as well as fine regulating the environmental behavior of magnetic material via micro-magnetic field.

Date Palm Seed Extract for Mild Steel Corrosion Prevention in HCl Medium

The inhibition effects of the date palm seed extract corrosion of mild steel in 0.5 M HCl at different concentrations are investigated by potentiodynamic polarisation (PDP), electrochemical impedance spectroscopy (EIS) and weight loss tests. Additionally, this study provides a fundamental understanding of aromatic adsorption on iron (Fe) surfaces. Furthermore, the surface morphology and the extracts are performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The maximum inhibition efficiency of 95, 96, and 91% were realised at 1400 mg/L for PDP, EIS, and weight loss, respectively. The inhibitive action of the DPS extract against mild steel corrosion in an acid solution has been supported by SEM analysis. The FTIR showed that the extract contained hydroxyl (−OH) and methoxyl (−OCH3) functional groups. The DFT depicted the adsorption sites at the oxygen (O) and carbon (C) atoms as deduced from the Fukui functions, Mulliken atomic charge, and the highest occupied molecular orbital-lowest occupied molecular orbital (HOMO-LUMO) analysis. The DPS preferred to form chemical bonds by donating electrons to the Fe surface. The coordinate bonds between the O and C atoms and the metal surface resulted in a high inhibition efficiency value. In conclusion, date palm seed extract is an effective inhibitor to protect mild steel from corrosion in an acidic medium.

Mechanism of Layer Formation during Gas Nitriding of Remelted Ledeburitic Surface Layers on Unalloyed Cast Irons

Unalloyed cast iron materials exhibit low tribological and corrosive resistance. In this respect, nitriding has a wide range of applications for steels. In the case of cast iron, the advantageous properties of nitrided layers are impaired by the presence of graphite. Electron beam remelting of cast iron surfaces prior to nitriding removes graphite. The homogeneous ledeburitic microstructure within the approx. 1 mm-thick remelted layer enables the formation of a dense compound layer during subsequent nitriding. The main objective of this study is to investigate the nitriding mechanism of unalloyed ledeburitic microstructures. Due to the complex relationships, investigations were carried out on both conventional ferritic and pearlitic cast irons and Fe-based model alloys containing one to four additional alloying elements, i.e., C, Si, Mn and Cu. The iron (carbo-)nitride composition (γ’, ε) of this compound layer depends on the gas nitriding conditions, the chemical composition of the substrates and the microstructural constituents. As a result, a schematic model of the nitriding mechanism is developed that includes the effects of the nitriding parameters and alloy composition on the phase composition of the nitriding layer. These findings enable targeted parameter selection and a further optimization of both the process and the properties.

Assessment of the inhibitive performance of a hydrazone derivative for steel rebar in a simulated concrete medium: Establishing the inhibition mechanism at an experimental and theoretical level

In the present work, a low-cost and practical approach based on an eco-friendly corrosion inhibitor is suggested for protecting steel rebar. To this end, a new hydrazone derivative, namely N'-(furan-2-ylmethylene)-2-(5-methoxy-2-methyl-1H-indol-3-yl) acetohydrazide (FMAH) was synthesized and its corrosion inhibition characteristics for steel rebar (STR) in chloride contaminated simulated concrete pore solutions (ClSCPS) were evaluated using experimental and theoretical methods. The electrochemical studies, which were conducted at several periods ranging from 1 h to 30 d indicated that the addition of FMAH to the ClSCPS significantly improved the passive film formation. It considerably increased film and charge transfer resistances at an early immersion stage, then decreased at longer immersion periods. Potentiodynamic polarization curves (PPCs) revealed that the investigated compound could be categorized as a mixed inhibitor with a predominance anodic effect. The gravimetric and potentiodynamic polarization studies confirmed corrosion inhibition efficiencies of 80.9% and 81.1%, respectively, for 1.0 mmol.L-1 FMAH after 30 d of exposure. Surface characterization of corroded and inhibited STR surface by X-ray photoelectron spectroscopy (XPS), SEM coupled with EDS, Raman spectroscopy, atomic force microscopy (AFM) and X-ray diffraction spectroscopy (XRD) revealed that inhibitor molecules chemically adsorbed on the STR forming a highly resistant protective layer against corrosive species. Theoretical modeling of inhibitor’s adsorption on the iron surface by the self-consistent-charge Density-functional tight-binding (SCC-DFTB) indicated the formation of several covalent bonds between carbon and oxygen atoms with the iron atoms. The analysis of FMAH-Fe (110) adsorption systems by projected density of states revealed that FMAH molecules adsorbed on the iron surface through a charge transfer process. The interesting results from the present work would open great opportunities for exploring the anti-corrosion performance of the investigated compound in concrete.

DFT and microkinetic investigation of oxygen reduction reaction on corrosion inhibition mechanism of iron surface by Syzygium Aromaticum extract

Corrosion of iron is an important and serious problem in materials. So far, many studies have been carried out to overcome the corrosion of iron. However, first-principle studies at the atomic level of iron corrosion processes based on electrochemical reactions are still very limited. Investigations based on electrochemical oxygen reduction reactions (ORR) are very important, because naturally corrosion is an electrochemical process. In this paper, the corrosion mechanism of the Fe(110) surface and the mechanism of corrosion inhibition by eugenol based on the electrochemical ORR are investigated using combinations of DFT and microkinetic models. We show that the ORR activity starts when the iron surface is covered by O atoms until the monolayer coverage is almost full, which indicates that the first stage of the iron corrosion process is not direct oxidation. After the iron surface is covered by O atoms, the corrosion process will begin with the occurrence of a proper ORR rate. In the presence of eugenol as a green corrosion inhibitor, the ORR activity is significantly lower, which also means that the corrosion rate is inhibited. This is confirmed by the higher overpotential value and lower TOF. In addition, the surface coverage is no longer dominated by free sites. Overall, our research provides new insights into designing green corrosion inhibitors for iron surface.

The use of TEA·H3PO4 and TEA·C18H30O3S as eco-friendly corrosion inhibitors in cementitious materials: An experimental and theoretical study

Chloride penetration, facilitated by drying-wetting cycles, poses significant threats to reinforced marine concrete structures. In this study, the corrosion inhibition effects of triethanolamine dodecylbenzene sulfonate (TEA·C18H30O3S, TDS) and triethanolamine phosphate (TEA·H3PO4, TP) were investigated using mortar specimens. Electrochemical tests including electrochemical impedance spectroscopy and potentiodynamic polarization test were performed. The morphology and Vickers hardness of the steel/mortar interface were analyzed. Molecular dynamics and quantum mechanical simulations were conducted to explore the interactions between the inhibitors and the iron surface. The results demonstrated that the inhibition efficiency of TP was high, while TDS only presented some effect within limited drying-wetting cycles. After 24 wetting-drying cycles, the inhibition efficiency of TP reached 59.29 %, TDS exerted a detrimental effect on reinforcement corrosion, and the inhibition efficiency was −410.96 %. At the mortar/steel interface, the irregular defects were curtailed and the Vickers hardness was improved by TP. Meanwhile, TDS entrained large hydration pores. The adsorption of the inhibitors on the iron surface is primarily through the benzene ring, PO and NC bonds, where the TEA-Fe adsorption is the most stable among the studied chemical components.

EXPLORING THE ROLE OF A BIO-SURFACTANT IN THE STABILIZATION OF HIGHLY CONCENTRATED IRON ORE SLURRY

The formulation and stabilization of highly concentrated solid-water slurry for transportation are gaining high interest. The influence of saponin extracted from A. auriculiformis on the stabilization of a high-grade iron ore sample in the slurry was studied. The collected iron ore powder and dried iron ore slurry samples were compared with the help of UV-vis, XRF, XRD, SEM, and EDS analysis. Moreover, the DSC spectral graph for both heat flow and mass loss with respect to time is plotted. The results confirmed that the surfactant molecules (aqueous A. auriculiformis) coated well on the iron surface which form an effective barrier between the iron ore particles. Further, the solubility of iron ore powder increased after adding an aqueous extract of Acacia auriculiformis as evident from the UV-vis spectral study.

Physical and engineering properties of chickpea (Cicer arietnum L.) for planter design

The design of a chickpea planter and its optimum performance requires physical and engineering properties of the grain varying with cultivars. Such properties include size, shape, mass, density, static friction coefficient, and repose angle etc. The cultivars viz. JG 16, HC 5, KWR 108, IPC 4-1, IPC 5-62, DCP 92-3, IPC 4-98 and JG 14 were investigated at 11.0±1.0 per cent moisture content using standard methodology. The grain size was presented in terms of major, intermediate, minor, and geometric mean diameters as 8.49-9.78, 5.91-7.23, 5.88-6.94, and 6.68-7.89 mm, respectively. The shape of the grain was presented in terms of sphericity which ranged from 0.78-0.81. The thousand seed mass, bulk density, and true density were 198-338 g, 830-880 kg m-3, and 1310-1350 kg m-3, respectively. The static friction coefficient was the least against aluminium followed by galvanised iron and mild steel surfaces with respective ranges of 0.37-0.40, 0.41-0.45, and 0.52-0.56. The angle of repose ranged from 26.4-27.7 degrees. There was a significant varietal difference in different physical and engineering properties of chickpeas except true density and angle of repose, where the difference was non-significant.

Unveiling the corrosion mechanism of 3-nitro-1,2,4-triazol-5-one (NTO) toward mild steel from ab initio molecular dynamics: how the “nitro-to-amino” reaction matters

The iron surface plays a crucial role in its own corrosion by facilitating the “nitro-to-amino” reaction of NTO and its anion with the assistance of hydrogen bonding.

Water-repelling behavior of the 1-D hematite nano-network.

Hematite is an attractive material used as electron transport layer in perovskite-based solar cells. Being hydrophilic in nature it attracts moisture, which can be damaging for perovskite layers. Therefore, it is important to make hematite moisture repelling, which can be beneficial for applications in solar cells or for protecting iron surfaces from further rust formation. In this work, we demonstrate that the systematic irradiation of nanostructured hematite with low-energy argon ions (Ar+) at various ion fluences can change the surface wettability as well as promote the formation of junctions between nanorods. The nano-welded network of the irradiated hematite turns out to be hydrophobic. Using TRI3DYN simulations, ion-induced surface roughening, the presence of surface oxygen vacancies, and joining between adjacent nanorods are predicted. Furthermore, the water-repelling behavior of the irradiated nano-network is evaluated using density functional theory (DFT) simulations by determining the interaction of water molecules with the surface. The interconnected hematite nano-network also shows a notable improvement in electrical conductivity.

Analysis of micro- and nanoscale heterogeneities within environmentally relevant thin films containing biological components, oxyanions and minerals using AFM-PTIR spectroscopy.

Minerals in groundwater interact with various chemical and biological species including organic matter, proteins, and prevalent oxyanions, resulting in surface coatings and thin films of these different components. Surface interactions and the surface adsorption of these components on both oxide and oxyhydroxide iron surfaces have been widely investigated using a variety of spectroscopic methods. Despite these numerous studies, there still remains uncertainty with respect to interactions between these individual components, as well as heterogeneities and phase segregations within these thin films. In this study, we investigate mixtures containing Fe-containing minerals, proteins, and oxyanions to better understand surface interactions and phase segregation using Atomic Force Microscopy PhotoThermal Infrared (AFM-PTIR) spectroscopy. The results of this study show that AFM-PTIR spectroscopy can identify both nano- and microscale heterogeneities present within these thin films that are difficult to discern with other more conventional techniques such as ATR-FTIR spectroscopy due to phase segregation and mineral surface interactions. Overall, AFM-PTIR spectroscopy provides insights into multi-component environmental films that are difficult to uncover using other methodologies. This method has the potential to differentiate between bound and unbound toxic species as well as biological components, including environmental DNA, which can be used to assess the fate and transport of these species in the environment.

Synthesis of an eco-inspired anticorrosive composite for mild steel applications.

We synthesised a polyaniline/mica (Mica-PANI) nanocomposite using naturally occurring muscovite mica by a top-down approach. The developed coating materials were characterised using a different technique to investigate their chemical and structural properties using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Furthermore, the electrochemical properties of the coating materials were investigated by linear sweep voltammetry (LSV). SEM images elucidate the composite's average particle diameter of the prepared nano-mica, approximately 80 nm. The existence of relevant functional groups and bonding in the prepared Mica-PANI composite material was confirmed by means of XPS and FTIR techniques. Moreover, the synthesised composite with 5% w/w shows high anticorrosion protection, i.e. 84 μm per year, compared to competing materials, including commercial paint and individual raw materials (0.35 mm per year). The anti-corrosive effect occurs mainly due to two opposing effects: the formation of an Fe(OH)3 passive layer on the steel surface by oxidation of surface iron atoms by the PANI and the barrier effect of mica NPs through inhibition of corrosive agents. Therefore, the eco-inspired composite could be an ideal cost-effective coating material to prevent the corrosion of mild steel surfaces.

Influence of silicon and cobalt laser alloying on the microstructure and nanomechanical properties of the gray cast iron surface layer

Influence of silicon and cobalt laser alloying on the microstructure and nanomechanical properties of the gray cast iron surface layer