Iron Substrate Research Articles

Molecular structure optimization design of inhibitors based on frontier orbitals theory

Imidazoline derivatives with 7 levels of HOMO energy and imidazoline quaternary ammonium salts with 4 different LUMO energy levels were designed by adjusting the hydrophilic and hydrophobic groups of the imidazoline molecule. The changes in adsorption bonding and electron transfer of the imidazoline molecule on the metal surface were calculated by the density functional based tight binding method (DFTB+). It was found that when the HOMO and LUMO energy levels matched the iron Fermi level more closely, the imidazoline molecule could undergo more electron transfer with the iron substrate, thereby forming a stronger adsorption bond with the matrix. The corrosion inhibition performance of the imidazoline groups was further tested by electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). Finally, a clear correspondence between the frontier orbital energy level of the imidazoline molecule and its corrosion inhibition performance was discussed, which could provide an effective solution for designing high performance corrosion inhibitor molecules.

Extended light absorption and enhanced photoelectrochemical activity of palladium‐decorated hematite nanotubes prepared by photodeposition method

Palladium particles were deposited on hematite nanotube surfaces via a facile photodeposition method. Anodization method was then used for direct vertical growth of hematite nanotube arrays (HNTs) on a pretreated iron substrate. Field emission scanning electron microscopy, X‐ray diffraction, diffraction reflection spectroscopy and X‐ray photoelectron spectroscopy analyses were then used to carry out morphological and structural investigations. Compared with the bare HNTs, Pd‐decorated hematite films (Pd/HNTs) exhibit intense visible light absorption and show a red shift of the band edge. Pd/HNTs are more photoelectrochemically active than the non‐decorated films, according to chronoamperometry measurements. Thus, a promising methodology has been developed for the design of a simple and effective photoelectrode for application in photoelectrochemical water splitting systems.

Tribochemical Mechanisms of Trimethyl and Triethyl Phosphite on Oxidized Iron in Ultrahigh Vacuum

The surface chemistry of model lubricant additives, trimethyl phosphite (TMPi) and triethyl phosphite (TEPi), is studied on oxidized iron in ultrahigh vacuum (UHV) and the results compared with the gas-phase lubrication of TEPi on oxidized iron in a UHV tribometer. Oxide films are grown on a polycrystalline iron substrate and characterized by X-ray photoelectron spectroscopy (XPS) and assigned to the formation of an Fe3O4 film. Measurements of the friction coefficient and contact resistance of the oxide films show that the oxide film remains intact while rubbing in UHV at a normal load of 0.29 N. It is found that phosphite esters adsorb on the oxide by electron donation to the phosphorus atom, with a binding energy that increases in the order tributyl phosphite > TMPi > TEPi, and correlates well with the location of the vacant lowest-occupied molecular orbital (LUMO) energy. The phosphite esters decompose via sequential P‒O bond scission to form adsorbed alkoxy species, which then react on the surface either by hydrogen addition to form the corresponding alcohol, or by hydrogen abstraction to yield an aldehyde. XPS studies of the surface shows that essentially no carbon remains after the TMPi has reacted, while a small amount of carbon is present when TEPi has decomposed. On heating, the phosphite esters convert to phosphate species. Gas-phase lubrication experiments in the presence of 1 × 10−7 Torr of gas-phase TEPi reveal that the friction coefficient is significantly reduced, where the friction reduction is found to increase with increasing reaction temperature. The friction reduction correlates well with the proportion of phosphate product formed in the film and indicates that the formation of phosphate tribofilm is primarily responsible for reducing friction. However, friction is also reduced for a reaction at ~ 300 K, lower than the temperature at which the adsorbed phosphite ester reacts, suggesting that its rate of decomposition could be accelerated by interfacial shear.

Anoxygenic photosynthesis and the delayed oxygenation of Earth\u2019s atmosphere

The emergence of oxygenic photosynthesis created a new niche with dramatic potential to transform energy flow through Earth’s biosphere. However, more primitive forms of photosynthesis that fix CO2 into biomass using electrons from reduced species like Fe(II) and H2 instead of water would have competed with Earth’s early oxygenic biosphere for essential nutrients. Here, we combine experimental microbiology, genomic analyses, and Earth system modeling to demonstrate that competition for light and nutrients in the surface ocean between oxygenic phototrophs and Fe(II)-oxidizing, anoxygenic photosynthesizers (photoferrotrophs) translates into diminished global photosynthetic O2 release when the ocean interior is Fe(II)-rich. These results provide a simple ecophysiological mechanism for inhibiting atmospheric oxygenation during Earth’s early history. We also find a novel positive feedback within the coupled C-P-O-Fe cycles that can lead to runaway planetary oxygenation as rising atmospheric pO2 sweeps the deep ocean of the ferrous iron substrate for photoferrotrophy.

Optimization of Microstructural Evolution during Laser Cladding of Ni Based Powder on GCI Glass Molds

In glass industry, laser cladding is an innovative surfacing technique allowing to deposit a layer of nickel to protect glass mold against corrosion, abrasion and thermal fatigue. This method (powder fusion by projection), well known in additive manufacturing represents a real technological leap for the glass industry. But during laser cladding of Ni-based powder on gray cast iron, cracks can be observed for some process conditions. These cracks are often due to the Heat Affected Zone that creates structural stresses linked to the development of a martensitic structure in the ferritic matrix of the lamellar graphite cast iron. The aim of this work is to observe the impact of laser cladding (without substrate pre-heating usually employed to limit cracking) on the coating behavior but also on the flake-graphite cast iron substrates. The microstructure and the mechanical properties were studied (SEM and microanalysis, microhardness) around the interface cladding/substrate. Also, the impact of the processing parameters (power P (1500-2300 W), scanning speed v (2.5-10 mm/s) and powder feeding rate PFR (24.5-32.5 g/min) was studied by using the ANOVA (ANalysis Of VAriance) technique. It has been observed that laser cladding on graphite cast iron is possible without cracks by limiting the linear energy induced by the process. Also, an optimization of the processing parameters (P, v, PFR) in order to obtain the industrial expected geometry of the coating has been proposed.

Application of Electrospark Deposition Process and Modified SHS Electrode Materials to Improve the Endurance of Hot Mill Rolls. Part 1. Features of Coating Formation on SPHN-60 White Cast Iron Substrates

Application of Electrospark Deposition Process and Modified SHS Electrode Materials to Improve the Endurance of Hot Mill Rolls. Part 1. Features of Coating Formation on SPHN-60 White Cast Iron Substrates

Modelling of phase composition of Sn-Fe layered system obtained by ion-plasma sputtering

The Mössbauer spectra on Iron and Tin nuclei in different states in the phases of the binary system Fe-Sn are modeled. Reference spectra of intermetallic compounds and α-Fe (Sn) solid solution were obtained. The spectra of Iron and Tin alloys of various concentrations were calculated. A comparison with the experimental spectrum of the layered Sn(4 μm)-Fe(10 μm) system obtained by ion-plasma deposition of Tin on an armco iron substrate and subjected to thermal annealing at 700°C showed a good correlation.

SURFACING – TECHNOLOGIES AND LAYER PROPERTIES (A REVIEW)

The overview includes the basic methods for obtaining surface layers: arc surfacing - submerged arc surfacing (SAS), tungsten inert gas arc surfacing (TIGS), metal gas surfacing (MIG/MAG), plasma surfacing (PS); electron beam surfacing (EBS); laser surfacing (LS); electroless cladding (ELC); friction stir surfacing (FSS). Layers are applied on carbon steels, low alloyed steels, highly alloyed steels, aluminium alloys, titanium alloys or ductile cast iron substrates. The data on the additive materials used are provided and data on the hardness and wear resistance of the layers is given.

Erratum to “Thermal Conductivity of Oxide Scale Thermally Grown on Iron Substrate Corrected by Temperature-dependent Interfacial Thermal Resistance in Laser Flash Measurement” [ISIJ International, Vol. 59 (2019), No. 3, pp. 398–403

Erratum to “Thermal Conductivity of Oxide Scale Thermally Grown on Iron Substrate Corrected by Temperature-dependent Interfacial Thermal Resistance in Laser Flash Measurement” [ISIJ International, Vol. 59 (2019), No. 3, pp. 398–403

Mechanically Robust and Repairable Superhydrophobic Zinc Coating via a Fast and Facile Method for Corrosion Resisting.

Zinc coatings and superhydrophobic surfaces have their own characteristics in terms of metal corrosion resistance. Herein, we have prepared a robust and repairable superhydrophobic zinc coating (SZC) based on a widely commercially available cold galvanized paint via a fast (within 10 min) and facile process for corrosion resistance. Specifically, the cold galvanized paint was sprayed onto the iron substrate, followed by acetic acid (HAc) etching and stearic acid (STA) hydrophobizing. The as-obtained sample was coded as Fe-Zn-HAc-STA and possessed an apparent contact angle of 168.4 ± 1.5° as well as a sliding angle of 3.5 ± 1.2°. The Fe-Zn-HAc-STA sample was mechanically durable and easily repairable. After being ultrasonicated in ethanol for 100 min, the superhydrophobicity was still retained. The Fe-Zn-HAc-STA sample lost its superhydrophobicity after being abraded against sandpaper with a load of 100 g and regained its superhydrophobicity after HAc etching and subsequent STA hydrophobizing. The corrosion resistance of the SZC was investigated by immersing the Fe-Zn-HAc-STA sample into the static or dynamic aqueous solution of NaCl (3.5 wt.%) and the lasting life of the entrapped underwater air layer (EUAL) was roughly determined by the turning point at the variation curve of surface wettability against immersion time. The lasting life of the EUAL iwas 8 to 10 days for the SZC in the static NaCl solution and it decreased sharply to 12 h in a dynamic one with the flow rate of 2 and 4 m/s. This suggests that the superhydrophobic surface provided extra corrosion protection of 8 to 10 days or 12 h to the zinc coating. We hope that the SZC may find its practical application due to the facile and fast fabrication procedure, the good mechanical durability, the easy repairability, and the good corrosion protection.

Surface‐enhanced Raman scattering studies of gold‐coated ripple‐like nanostructures on iron substrate achieved by femtosecond laser irradiation in water

AbstractDuring the past several years, numerous efforts have been accomplished on designing efficient surface‐enhanced Raman scattering (SERS) substrates with high sensitivity, good reproducibility, and recyclable nature. However, it still remains a significant challenge to realize all these qualities in a single substrate. We have fabricated ripple‐like nanostructures (NSs) on Iron (Fe) substrate using femtosecond (fs) laser irradiation of Fe target in distilled water. These ripple‐like structures had periodicities in the range of ~90–190 nm, which was confirmed from the analysis of field emission scanning electron microscope (FESEM) data. We subsequently deposited a thin layer of gold on these ripple‐like Fe NSs using thermal evaporation. Later, these coated NSs were effectively utilized as SERS substrates for methylene blue (MB) detection and were found to be sensitive evident from the data obtained at a very low concentration of 500pM. Furthermore, we observed that the SERS signal variations on the substrate were <11.2% indicating the reproducible nature of these substrates. Additionally, we demonstrate that these substrates can be reused (we establish this for three times consecutively) by detecting malachite green (MG) and an explosive molecule (picric acid, PA) followed by the mixture compound (Rhodamine 6G+MB) through employment of simple cleaning procedures. The detected molecular concentrations in terms of masses were found to be 3.2 pg, 36.5 pg, and 23 ng for MB (for a concentration of 500pM), MG (for a concentration of 5nM), and PA (for a concentration of 5μM), respectively. Furthermore, these Fe NSs exhibited superior batch‐to‐batch reproducibility with a relative standard deviation (RSD) value of ~l4%. The proposed method of fabricating ripple structures as SERS platforms are highly feasible, reliable, and have great potential for on‐site detection of several analyte molecules with an easily transportable Raman spectrometer.

Evaluation of growth behaviour of vanadium carbides-reinforced iron-based surface compound layer by in-situ reaction

The growth of vanadium carbide reinforced iron substrate surface compound layers are investigated, where the compound coatings were fabricated by in situ synthesis process at 950 °C, 1000 °C and 1050 °C in 1–5 h, respectively. A detailed characterization about the microstructural change of compound layer is given by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The obtained vanadium carbide compound layers are composed of V2C and V8C7. V2C and V8C7 have different microstructures and crystal orientations. The thickness of the vanadium carbide layer ranges from 16.62 ± 0.16 μm to 81.47 ± 0.63 μm in different process conditions. Growth kinetics of the layer follows the parabolic rules and the calculated activation energy value is Q=415.7KJ/mol. Both the heating treatment temperature and the holding time constantly influence on the microstructure and growth behaviour of the vanadium carbide compund layer.

A Chemical, Mechanical, and Tribological Analysis of DLC Coatings Deposited by Magnetron Sputtering

Diamond-like carbon is one of the most studied and used solid lubricants on the market. Despite this large use and its outstanding mechanical and tribological properties, there are still some unclear aspects related to its self-lubricant properties, and some drawbacks in the deposition methods. We deposited “soft” DLC films on Si(100), iron, and stainless steel substrates by PVD magnetron sputtering technique with a Cr/CrN adhesive interlayer. The DLC films were characterized from a chemical, mechanical, and tribological point of view. Our aim was to connect the coating chemical and mechanical characteristics to the different conditions used for the deposition, such as discharge power and substrate–target distance. We found a stronger sp3 dependence on the discharge power for DLC deposited closer to the target. The tribological results did not depend on the chosen substrate–target distance, but rather on the hardness of the substrate. This could be ascribed to the better mechanical coupling of soft DLC films on harder substrates.

Pelapisan Logam Menggunakan Plasma

One of the ways to improve the quality of the material is by using the thin layer deposition techniques on the material surface. DC magnetron sputtering is one of the methods frequently used to do so. This method uses plasma to create a thin layer on the material's surface. In this research, flyback circuit is used to generate plasma. This research examines the effects of electrodes’ gap and sputtering process time on the width of marks that appear on the substrate’s surface. The electrodes’ gap varies in range of 1, 2, 3, and 4 cm, whereas the sputtering process time varies in range of 36, 72, 108, 144, and 180 minutes. The substrate used in this research is iron and the coating materials used are aluminium and copper. This research uses plate-shaped electrodes in the coating process. The sputtering process resulted in the appearance of marks on the substrate’s surface. The marks were compared qualitatively with every gap range of electrodes, sputtering process time, and the coating material used. Next, they were categorized into 6 groups according to the thickness of the marks’ layer in order to obtain quantitative data which were then made into graphics. The results of this research show that silver coating material takes the shortest time to coat iron substrate, which is 36 minutes. In 36 minutes, the marks produced by silver coating fall under the group with the highest marks, compared to other coating materials. This research also shows that alteration of the electrodes' gap will affect the voltage of electrodes and the coating’s thickness groups. The further the gap between the electrodes, the higher the electrodes’ voltage and the coating’s thickness groups will be.

Effect of oxidation on thermal fatigue behavior of cast tungsten carbide particle/steel substrate surface composite

Abstract

Synthesis of ultra-long aluminum nitride nanowires with excellent photoluminescent property by aluminum chloride assisted chemical vapor reaction technique

Abstract Aluminum nitride (AlN) nanowires were performed on iron substrate using aluminum powders as material precursor by anhydrous aluminum chloride (AlCl3) assisted chemical vapor reaction (CVR) method. Yield production of AlN nanowires was significantly enhanced with AlCl3 addition into Al powders due to generating of intermediate gaseous AlCl, which further reacted with N2 to form AlN nanowires. With AlCl3 addition, a thin Fe film on Fe substrate can be transformed into Fe nanoparticles, which served as a catalyst in promoting the formation of AlN nanowires. The length of single-crystalline AlN nanowires was up to hundreds of microns. The formation and growth of AlN nanowires were most likely controlled by vapor–liquid–solid growth mechanism and AlCl3 assisted chemical vapor transport mechanism. The luminescence bands in the range of violet-green luminescence suggest its promising application in light-emitting devices.

Thermal Conductivity of Oxide Scale Thermally Grown on Iron Substrate Corrected by Temperature-dependent Interfacial Thermal Resistance in Laser Flash Measurement

Thermal Conductivity of Oxide Scale Thermally Grown on Iron Substrate Corrected by Temperature-dependent Interfacial Thermal Resistance in Laser Flash Measurement

Sorption mechanisms of diphenylarsinic acid on ferrihydrite, goethite and hematite using sequential extraction, FTIR measurement and XAFS spectroscopy

Diphenylarsinic acid (DPAA) is an organoarsenic compound derived from abandoned chemical weapons. DPAA sorption by iron (hydr)oxides is of considerable importance but remains largely unexplored. The current study aimed at investigating the sorption mechanisms of DPAA on ferrihydrite, goethite and hematite using both macroscopic sorption kinetics and sequential extraction procedure (SEP) as well as microscopic Fourier transformed infrared (FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopic techniques. Sorption kinetics studies show that >93% of added DPAA (4–100 mg L−1) was sorbed on ferrihydrite and hematite within 5 min, while only 84% of added DPAA (100 mg L−1) was sorbed on goethite after 24 h. The sequential extraction results and FTIR measurements reveal that DPAA formed simultaneously inner- and outer-sphere complexes on goethite and hematite, but predominantly inner-sphere complexes on ferrihydrite with limited formation of outer-sphere complexes (<15%). A combination of SEP, FTIR and EXAFS techniques further enables identification of the interfacial reactions between DPAA and solid surfaces of iron (hydr)oxides and the mechanisms involved. Results indicate that DPAA interacted with these iron (hydr)oxides via (1) electrostatic attraction or hydrogen bonding, (2) surface complexation and (3) complexation embedded inside the mineral particles. EXAFS studies further demonstrate that DPAA formed mainly bidentate binuclear corner-sharing (2C) complexes regardless of the iron substrate, with As-Fe distances at 3.19–3.32 Å. Comparison of these results with available data in the literature on inorganic, methyl and phenyl arsenics (As) suggests that it is the phenyl group substitution that finally determines the predominance of 2C complexes. Results from the present study will improve our knowledge of DPAA interaction with solid surfaces and may help in the prediction of the environmental fate and environmental risk management of DPAA in the soil-water system.

Simultaneous increase of friction coefficient and wear resistance through HVOF sprayed WC-(nano WC-Co)

Generally, well wear resistance corresponds to low friction coefficient. While, well wear resistance and high friction coefficient are needed in brakes for short braking distance and long serving life. Ceramics possess high hardness which correspond well wear resistance. Cobalt is often used as bond phase of tungsten carbide ceramic, which will increase the toughness of tungsten carbide. While, the stiffness of WC-Co will decrease after cobalt is introduced into tungsten carbide, which will lead to the decrease of friction coefficient. To increase the stiffness and the friction coefficient of WC-Co, nano WC particles were introduced into cobalt binder phase which formed WC-(nano WC-Co).In this work, WC-(nano WC-Co) coatings were prepared through high velocity oxygen fuel (HVOF) spray on the vermicular iron substrate in order to increase friction coefficient and wear resistance simultaneously. The microstructure, mechanical property and wear performance of the coating were investigated.It was found that the microhardness of WC-(nano WC-Co) coatings had the highest hardness of 1393 ± 13 HV with 50% nano WC-10Co-4Cr. Meanwhile, its friction coefficient was obviously increased to 0.7, which was three times higher than that of the vermicular cast iron and higher than both of the micro-sized and nano sized WC-Co. Its wear mass loss of WC-(nano WC-Co) coating was much lower than that of the vermicular cast iron and lower than both of the micro-sized and nano sized WC-Co. The friction coefficient and wear resistance of WC-(nano WC-Co) were increased simultaneously.

Characterization of wear properties of the functionally graded material deposited on cast iron by laser-aided additive manufacturing

In this study, functionally graded material (FGM) was deposited on cast iron substrate by laser-aided additive manufacturing (LAAM). Inconel 625 nickel-base superalloy was firstly deposited on the substrate as a buffer layer, on which the stainless steel 420 (SS420) layers were subsequently prepared. The cracking issue was successfully eliminated in the deposited materials. With the optimized process parameters, the FGM with thickness up to 4.0 mm was achieved without cracks and other obvious defects. The SS420 layers showed fine dendritic microstructure derived from the rapid cooling rate of the LAAM process. Wear test results indicated that the FGM shows excellent wear resistance, especially under lubricated condition.