Iron Substrate Research Articles

Metagenomic analysis of Fe(II)-oxidizing bacteria for Fe(III) mineral formation and carbon assimilation under microoxic conditions in paddy soil

Microbially mediated Fe(II) oxidation is prevalent and thought to be central to many biogeochemical processes in paddy soils. However, we have limited insights into the Fe(II) oxidation process in paddy fields, considered the world's largest engineered wetland, where microoxic conditions are ubiquitous. In this study, microaerophilic Fe(II) oxidizing bacteria (FeOB) from paddy soil were enriched in gradient tubes with FeS, FeCO3, and Fe3(PO4)2 as iron sources to investigate their capacity for Fe(II) oxidation and carbon assimilation. Results showed that the highest rate of Fe(II) oxidation (k = 0.836 mM d−1) was obtained in the FeCO3 tubes, and cells grown in the Fe3(PO4)2 tubes yielded maximum assimilation amounts of 13C-NaHCO3 of 1.74% on Day 15. Amorphous Fe(III) oxides were found in all the cell bands with iron substrates as a result of microbial Fe(II) oxidation. Metagenomics analysis of the enriched microbes targeted genes encoding iron oxidase Cyc2, oxygen-reducing terminal oxidase, and ribulose-bisphosphate carboxylase, with results indicated that the potential Fe(II) oxidizers include nitrate-reducing FeOB (Dechloromonas and Thiobacillus), Curvibacter, and Magnetospirillum. By combining cultivation-dependent and metagenomic approaches, our results found a number of FeOB from paddy soil under microoxic conditions, which provide insight into the complex biogeochemical interactions of iron and carbon within paddy fields. The contribution of the FeOB to the element cycling in rice-growing regions deserves further investigation.

Research on Mechanical Property of CoMo and CoMoP Coatings Electrodeposited on Iron Substrate

Research on Mechanical Property of CoMo and CoMoP Coatings Electrodeposited on Iron Substrate

Surface modification of metal substrates using dielectric barrier discharge plasma and the wettability study

BackgroundForming endurable coatings on the surface of metals in a simple, green, efficient manner is still challenging. Plasma surface modification offers an effective method to alter metal surfaces’ physicochemical properties and endow them with new functionalities. MethodsA DBD plasma method is presented for the surface modification of metals using perfluorooctyltriethoxysilane (POTS) and polyethylene glycol (PEG 200) as the precursors. Systematic experiments were carried out against galvanized iron to investigate the process feasibility. This method was further expanded to diverse metal substrates to examine the process versatility and practical applications. Significant findingsThe surface of the galvanized iron substrates were successfully modified by the POTS and PEG 200 precursors to form hydrophobic coatings and hydrophilic coatings, respectively. The composition, morphology, surface roughness, and wettability of the metal substrates could be adjusted by the plasma treatment time. The plasma technique exhibits have high efficiency and good versatility in tuning the wettability of different metal substrates. Furthermore, the plasma-modified substrates also displayed improved corrosion resistance via the salt spray test. This work enriches the study of DBD plasma surface modification as an effective method to functionalize metals with desirable properties.

Synthesis of Trivinylisooctyl POSS and Its Application in UV-Curing of Polyurethane Acrylate Coatings

To improve the overall performance of polyurethane acrylic (PUAs) coatings applied to an iron or wood substrate, a modifier, trivinylisooctyl polyhedral oligomeric silsesquioxane (TVi7iso–POSS), was successfully synthesized by a polycondensation reaction in the presence of an organotin catalyst. TVi7iso–POSS is a POSS derivative possessing three olefin and seven isooctyl bonds; its molecular structure was confirmed by FT-IR, 1H-NMR, and mass spectrometry. The synthesized TVi7iso–POSS was then used as a modifier with butyl methacrylate (BMA), dodecafluoroheptyl methacrylate (DFMA), difunctional PUA (PUA–2), and photo-initiator 1173 to produce a novel polyurethane coating (PFMPUAs) via UV-curing. The performance of the obtained PFMPUAs coating was analyzed via X-ray photoelectron spectrometry, SEM, atomic force microscopy, TGA, and differential scanning calorimetry. The newly synthesized modifier, TVi7iso–POSS, enhanced the thermal stability, hardness, flexibility, impact resistance, and adhesion of the PUAs coating and maintained its good light transmittance. Moreover, the PFMPUAs coating exhibited better overall performance compared to the previously studied PUAs coating when the addition of TVi7iso–POSS and DFMA was 15 wt.% of PUA–2. Therefore, the PFMPUAs coating has potential applications in the field of environmentally friendly coatings.

Abrasion Power of Ti and Ni Diamond-Coated Coatings Deposited by Cold Spray

In this work, the cold spray technique was used to deposit nickel and titanium coated diamond powder on cast iron and aluminum substrates. To analyze the deposition mechanism, the diamond powders were observed before and after the process using a microscope and scanning electron microscope (SEM). The adhesion response of the Ni and Ti coatings was investigated during the study. Pin-on-disk tests were then performed to identify the abrasion mechanism of the coated samples and the wear resistance of the Si3N4 ceramic balls. Experimental tests were adopted to determine the significant operating variables, i.e., the local linear speed and the applied load. The modification of the diamond particles in shape, distribution, and the residual debris of Si3N4 on disk were compared before and after the tribological test to analyze the abrasion and wear resistance of the ceramic balls.

Molecular dynamics study on wetting characteristics of lead droplet on iron surface at high temperatures

The wetting characteristics of a lead (Pb) droplet on an iron (Fe) surface at high temperatures are vital in reactor-related applications. The wetting characteristics of the lead droplet on the iron surface at different temperatures have been investigated by molecular dynamics with the generalized embedded atom method. The spreading process of the lead droplet can be divided into stages dominated by momentum and surface tension, respectively. For the two stages, the spreading radius R of the precursor film (PF) of the lead droplet increases with time t, but the increase of the latter stage is significantly smaller than that of the former one, and the equations of R vs. t are R~t0.5092 and R~t0.2078, respectively. The contact angle of the lead droplet on the iron surface decreases with the increase of the temperature at the same time. In the stage dominated by momentum, the velocity field of the lead droplet presents an overall trend of downward flow. In the stage dominated by surface tension, the flow velocity in the region near the liquid-vapor interface of the lead droplet is significantly higher than that in its internal region, and the velocity of the PF is extremely small. The atoms of the PF of the lead droplet are regularly distributed in the interstitial positions on the iron surface during the spreading process, and its diffusion mechanism on the iron surface is the surface near-neighbor interstice hopping mechanism. Furthermore, the iron substrate is corroded by the liquid lead during the wetting process, and the corrosion is aggravated with both the increase of the time and the temperature.

Development of Numerical Calculation Method of Formation of Corrosion Products in Galvanic Corrosion

A numerical calculation method was developed for obtaining the corrosion product chemical distribution in galvanic corrosion of a zinc-coated iron substrate under atmospheric conditions. A one-dimensional model, in which the width of the solution was mathematically divided into minute elements, while the solution height (hsol) perpendicular to the substrate surface was treated as a nongeometric variable, was applied to the developed calculation method. It was confirmed that time step could be larger when corrosion product formation was calculated based on Gibbs free energy changes of the reactions. The developed calculation method was validated by the qualitative agreements between measured and calculated results. In the measured and the calculated results, it was confirmed that the potential difference between Zn and Fe was larger and the corrosion products formed in lower Cl− concentration in the stability diagram were formed in the lower NaCl concentration solutions. Because the developed calculation method is suitable for the calculations in which hsol is thin and is variable and corrosion period is long, it is suitable for the calculations of atmospheric corrosion.

Mechanical properties and wear resistance of direct energy deposited Fe–12Mn–5Cr–1Ni-0.4C steel deposited on spheroidal graphite cast iron

This study investigates the wear resistance of an Fe–12Mn–5Cr–1Ni-0.4C (high-manganese steel) produced by direct energy deposition (DED) and spheroidal graphite cast iron. The high-manganese steel was deposited on the spheroidal graphite cast iron substrate. Near the deposit/substrate interface, the graphite phases of the cast iron are completely solutionized owing to the low carbon content of the high-manganese steel. In addition, the steel was deposited with a dense microstructure without interfacial cracks owing to the strong austenite stabilization effect. The wear behavior for various wear loads and sliding speeds was studied using ball-on-disk tribology tests with counterpart balls (KS STB2 bearing steel). The results show that the wear rates of the deposited high-manganese steel and the spheroidal graphite cast iron depended more on the wear load than on the sliding speed. At a low wear load of 20 N or less, the spheroidal graphite cast iron showed a higher wear rate than the deposited high-manganese steel owing to the self-lubricating effect of graphite. When the wear load condition was 50 N, the high-manganese steel had a higher wear resistance than the cast iron owing to the work-hardening effect. Therefore, it is expected that high-manganese steels, produced by DED, with high wear resistance under a high wear load will be effective for repairing spheroidal graphite cast iron products.

Effect of curing process and pyrolysis temperature on the microstructure, adhesion and corrosion resistance of PCS-derived coatings

Polycarbosilane-derived (PCS-derived) coatings were fabricated on iron substrate by dip-coating method. The effects of curing process including air curing and divinylbenzene (DVB) curing and pyrolysis temperature on the coating microstructure, adhesion and corrosion resistance in 3.5 wt% NaCl solution were systematically studied. Both curing process and pyrolysis temperature have a significant influence on the micro-cracks, surface roughness and ceramicization of the coatings. PCS-derived coatings fabricated by air curing process has the lower micro-crack width due to the higher curing degree. No matter in which curing process, the average micro-crack width and surface roughness of the coatings pyrolyzed at 600 °C are higher than those of the coatings pyrolyzed at 400 °C or unpyrolyzed. Electrochemical test results indicate that all coatings can protect the iron substrate from corrosion. The corrosion resistance of the PCS-derived coating is dominated by the microstructure including micro-cracks, surface roughness and ceramicization. Coatings fabricated through air curing and pyrolyzed at 400 °C have better corrosion resistance due to less micro-cracks, lower roughness and higher ceramicization. Corrosion resistance mechanism of the PCS-derived coatings was also analyzed.

Wear-resistant coatings produced by high-speed selective laser sintering of wet-milled W[sbnd]Fe powders: Phase composition, microstructure, and properties

The features of the synthesis of a composite coating based on η-carbide (Fe,W)6C and tungsten applied to an iron substrate have been studied. Coatings are produced by high-speed selective laser sintering of WFe powders mechanically alloyed in a liquid hydrocarbon. The phase composition of the coating starts its formation from the nucleation and growth of (Fe,W)6C carbide inclusions of up to 400 nm in size. The applied coating has a hardness of 16 GPa, high wear resistance, and friction coefficient of 0.22 to 0.28 measured in dry fretting wear test with steel and WC–Co balls under a load of 10 to 100 N.

HVOF sprayed Ni–Mo coatings improved by annealing treatment: microstructure characterization, corrosion resistance to HCl and corrosion mechanisms

In this study, HVOF spraying technology was employed to deposit the Ni–Mo alloy coating on nodular cast iron substrate. Post–spray annealing treatment was used to modify the microstructure and corrosion property of Ni–Mo coating. The microstructural evolution and corrosion resistance to HCl of both the as-sprayed and annealed Ni–Mo coatings were investigated. Results show that an unoxidized Ni–Mo coating with the porosity of 0.62% and bonding strength of 58.8 MPa can be achieved by HVOF. Electrochemical tests indicate that the influence of temperature on corrosion behavior of the as-sprayed Ni–Mo coating in 15wt.% HCl solution follows the order: 40 °C > 60 °C > 20 °C. With increasing the concentration of HCl solution, corrosion resistance of the as-sprayed Ni–Mo coating decreases. Post–spray annealing treatment has a significant effect on the microstructural evolution of Ni–Mo coating, including interfacial bonding quality, coalescence of micro-voids, phase transformation within coating and element diffusion reactions from substrate into coating. Annealing treatment accelerates the diffusion of Fe and C from nodular cast iron substrate into Ni–Mo coating with forming Mo2C and NiFe phases, which results in the enrichment of Mo. The 850 °C annealed Ni–Mo coating possesses the best corrosion resistance in 15wt.% HCl solution, which is due to the improved interfacial bonding and the low extent of Fe/C diffusion from substrate into coating, whereas the dramatical reduction of corrosion resistance of the 950 °C annealed case can be mainly attributed to the large-scale formation of NiFe and Mo2C phases within coating.

Cold Spray of Nickel-Based Alloy Coating on Cast Iron for Restoration and Surface Enhancement

Cold spray is an emerging additive manufacturing process that allows particles to be coated onto the surface of a base material without melting. It is suitable to repair components made from temperature-sensitive materials, such as grey cast iron, which cannot be easily restored using conventional methods like welding or thermal spray. In this study, the nickel-based alloy Inconel 625 was successfully coated onto a grey cast iron (GJL250) using a cold spray process, and extensive experiments were carried out to study the effects of diffusion between the coating and the substrate after heat treatment at 400, 600, 850 and 1050 °C for 3 and 6 hours durations. The coatings in all conditions were dense (0.25% to 3%) and had defect-free interfaces. Under heat treatment, the diffusion layer increased in thickness with increasing temperature and duration due to atomic diffusion. The Inconel 625 coating is also shown to be effective against oxide growth as compared to grey cast iron. The hardness of the coatings is also stable at high temperatures. The heat-treated coatings at 600 °C achieved a peak hardness of around 500 HV, which is 30% and 60% higher than the as-sprayed coating and grey cast iron substrate, respectively, because of the possible formation of recrystallized nanostructured grains and strengthening precipitates. These findings demonstrate the potential application of using cold spray on nickel-based alloy coatings for restoration and surface enhancement of grey cast iron components, such as engine blocks and pump housings.

Relocation, attachment and survival of zebra mussels (Dreissena polymorpha) on aluminum, chrome, iron, galvanized-iron, zinc, copper and copper-alloy substrates

Relocation, attachment and survival of zebra mussels (Dreissena polymorpha) on aluminum, chrome, iron, galvanized-iron, zinc, copper and copper-alloy substrates

Assesment of Chemical Oxygen Demand Reduction from Textile Waste Water by ZnO Nanofilm Reactor

This research paper presents the results of a photocatalysis-based treatment that uses ZnO-based semiconductors coated on galvanized iron plates attached to a rotating reactor and provides the result in the form of change in parameters like Chemical Oxygen Demand (COD). Other treatment units like sedimentation aided with coagulation and flocculation, sand filter, and activated carbon filter were used before and after the nano reactor respectively. It was found that for galvanized iron substrate there is a reduction of 85.76% when wastewater is retained for 2 hours in a reactor, and subsequently 92.80%, 93.53%, and 94.52% for a retention time of 4 hours, 6 hours, and 8 hours.

Interfacial Microstructure and Bonding Area of Sn-based Alloy-GG25 Gray Iron Bimetallic Material Using Flux, Sn, and Sn-Zn Interlayer Compound Casting

A bimetallic casting consisting of GG25 gray iron substrate and Sn-based alloy using the liquid-solid technique has been studied in this paper. Three different pretreatment processes of gray iron surface substrates including flux only, flux and Sn powder, and flux and Sn-8.8% Zn powder eutectic alloy surface treatment were adopted for the aim of improving the quality of tinning, the interfacial structure, and the bonding area of the Sn-based alloy/gray iron bimetallic composite in order to promote the bonding quality of bimetallic castings. Microstructure characterization on the bonding interface was conducted. The novel tinning material for gray cast iron substrate comprising of Sn-8.8% Zn eutectic alloy powder in combination with flux interlayer improved the bonding area, the interfacial bimetal structure, and the shear stress. This improvement is due to the higher interface reaction of Zn with Fe that leads to the formation of a very thin layer of Fe-Zn and Fe-Sn intermetallic phases.

Insights into the Correlation between Residual Stresses, Phase Transformation, and Wettability of Femtosecond Laser-Irradiated Ductile Iron.

Despite numerous studies on the wettability behavior of ductile iron after ultrafast laser structuring, the correlation between the phase change due to the interaction with an intense pulse and wettability is not yet well understood. In the present work, phase transformations of ductile iron substrates after femtosecond laser irradiation are investigated and correlated with the wettability behavior. Laser parameters such as fluence (F), cumulative fluence (CH), number of pulses (N), and scan speed were varied to produce hierarchical structures with different morphologies and phase concentrations. Our outcomes indicated that substrates with higher concentrations of austenite in the absence of hierarchical structures have a superhydrophilic nature despite being stored in an ambient atmosphere for several days and the application of a vacuum process. In addition, we measured the concomitant residual stresses after laser irradiation using the X-ray diffraction (XRD) method and established a relationship with the doses of CH and induced micro/nanostructures. Transmission electron microscopy (TEM) revealed that laser-structured surfaces are covered with oxides; moreover, phase transformation occurs at the near-subsurface layer.

New Geochemical Framework and Geographic Information System Methodologies to Assess Element Occurrence, Persistence, and Mobility in Groundwater and Surface Water

This study presents a geochemical framework and geographic information system (GIS) method for assessing the intrinsic potential of surface water and groundwater to mobilize arsenic, molybdenum, selenium, uranium, and vanadium. The method was created using published groundwater and surface water geochemical data from the National Uranium Resource Evaluation database for 2302 groundwater and 915 surface water samples. The method was evaluated using published groundwater geochemical data from the Texas Water Development Board. Geochemical data were analyzed in GIS. Samples were categorized by environmental condition, which was determined by using reduction–oxidation—as indicated by pe—and pH ranges for each sample based on geochemical mobility frameworks developed by Smith (2007) and Perel’man (1986). Reduction–oxidation and pH influence the occurrence, persistence, and mobility of arsenic, molybdenum, selenium, uranium, and vanadium in groundwater and surface water. Reduction–oxidation categories were assigned to water samples using concentrations of redox-active constituents, including dissolved oxygen, iron, manganese, and sulfur. The presence of iron substrates and hydrogen sulfides were considered in relation to mobility mechanisms. Twelve-digit hydrologic unit code (HUC) boundaries were used in GIS as analysis areas to determine the most commonly occurring environmental condition in each HUC. The resulting maps identify the environmental conditions in different areas that can be used to identify where the elements are mobile. This methodology provides a systematic approach to identify areas where elements in groundwater and surface water may occur and persist and may be transferable to other locations.

Wet ball milling and subsequent high-speed selective laser sintering of Nb[sbnd]Cu powders for applying wear-resistant coatings

The work investigates niobium-carbohydride- and copper-based powders prepared via wet ball milling of niobium and copper in petroleum ether, including their phase composition evolution under heat treatment. High-speed selective laser sintering of the prepared powders on iron substrates provides gradient coatings ~70 μm thick. The outer layer of the coating contains phases of NbC0.75, Nb2C, (Fe,Nb)6C, Cu, and Fe, whereas the 10-μm layer adjacent the substrate shows the presence of NbC0.75, (Fe,Nb)6C, Fe2Nb, Сu, and Fe. Dry friction with a WC–Co counterbody does not cause wear of the coatings, and the friction coefficient being ~0.6. High wear resistance of the coatings results from their structure including regions containing nanosized niobium carbides (50–500 nm) with a hardness of ~11 GPa, regions of Fe + Fe2Nb eutectic reinforced with niobium carbide inclusions with a hardness of 6.5 GPa, and copper inclusions working as a solid lubricant in tribological tests.

Evolution of Nanostructured Carbon Coatings Quality via RT-CVD and Their Tribological Behavior on Nodular Cast Iron

One of the most critical problems in industry is the wear of materials. Graphene, as a tribological coating, has shown a tremendous impact on sliding surfaces. In this work, a few layers of graphene were grown on a nodular cast iron substrate, a material used in camshafts. The studied synthesis parameters in a rapid thermal chemical vapor deposition (CVD) furnace and the quality of the final coating are presented. The influence of hydrogen flow and cooling rate was evaluated, obtaining the best results in the few layers of graphene structure and deposition at 10 sccm and 4 °C/min. A standard ball-on-disk tribometer was used to assess the coefficient of friction on a few layers of graphene on nodular cast iron substrates. Laboratory test results show that the few layers of graphene coating resulted in a 60% reduction in coefficient of friction and close to a 70% reduction in volume removed versus the uncoated substrates. The surface of the substrate was not modified before a few layers of graphene growth to have a working surface close to camshafts obtained by the industrial process at ARBOMEX SA de CV.

Laser-Induced Hydrothermal Growth of Iron Oxide Nanoparticles on Diverse Substrates for Flexible Micro-Supercapacitors

State-of-the-art microdevice fabrication requires patterned growth of functional nanomaterials on the desired position of the desired substrate. However, it is challenging, particularly in conventional hydrothermal synthesis, due to difficulties generating a local high-temperature field at the desired place. We introduce a laser-induced hydrothermal growth (LIHG) process for the rapid and selective synthesis of iron oxide nanoparticles (NPs). The substrates absorb the laser energy to generate a local high-temperature field necessary for the growth of iron oxide NPs. On various substrates, a dome-like structure comprising many iron oxide NPs is selectively synthesized within a localized temperature field. The LIHG process has several advantages for iron oxide NP growth, including rapidity, seedless growth, substrate compatibility, position selectivity, and patterning availability. Using its advantages, the LIHG process is used to fabricate flexible micro-supercapacitors based on laser-carbonized colorless polyimide films with iron oxide NPs.