Argon Oxygen Research Articles

Properties of ten-year-aged argon oxygen decarburization stainless steel slag

Properties of ten-year-aged argon oxygen decarburization stainless steel slag

Characterization and structural analysis of RF magnetron sputtered strontium stannate thin films

This paper presents physical and morphology properties of strontium stannate (SrSnO 3 ) perovskite-type as a candidate of an n-type material thin film for organic-inorganic hybrid diode heterojunction for optoelectronics application. Typical wet-process of SrSnO 3 deposition produce thick film and having 10 -8 S/cm order in conductivity. The SrSnO 3 thin films were deposited on ITO glass substrates by RF magnetron sputtering using a purity 99.9% SrSnO 3 target with 5.0 mTorr of gas pressure and 100 W of RF power at room temperature. The gas composition of pure argon (75%) and reactive oxygen gas (25%) was used for 60 min. XRD diffraction patterns revealed that the thin films are orthorhombic crystal structure with lattice parameter a=5.7040 Ǻ, b=8.06 Ǻ and c=5.7080 Ǻ with a strong orientation in the (002) direction. SEM images showed that films exhibited uniform surface morphology with a roughness average of R a =2.258 nm and thickness of 311 nm. The EDX spectrum confirmed the presence of O, Sr, and Sn elements in the films with 75.22%, 8.29%, 16.49% in atomic number, respectively. The films were having a conductivity of 8.33x 10 2 S/cm with low resistivity of 12.4x 10 -3 W -cm.

Improved internal model control method for carbon content of argon–oxygen refining ferrochromium alloys

We propose an improved internal model control method for the carbon content in the production process of argon–oxygen refining ferrochromium alloys. In the actual process, the control output is restricted and cannot fully demonstrate the control effect. Therefore, by decomposing the traditional internal model controller, we achieved saturation compensation, overcoming this limitation. In addition, by referring to the current production process, the smelting stages with different carbon-content ranges were determined. Combined with the actual equipment conditions, an anti-saturation internal model controller structure and a controller saturation numerical expert system were constructed, forming a fully improved internal model control system. The proposed method fully utilizes the steady-state error-free characteristic of the internal model control, achieving the preset control goal and significantly shortening the smelting time and improving the smelting efficiency.

Compound Control Method of Carbon Content in Argon–Oxygen Refining Ferrochromium Alloy

Compound Control Method of Carbon Content in Argon–Oxygen Refining Ferrochromium Alloy

Inclination Effect on Mixing Time in a Gas–Stirred Side–Blown Converter

Small‐scale physical models are commonly used to investigate gas‐stirred processes in steelmaking practice. The argon oxygen decarburization (AOD) converter is among various processes widely used in the metallurgy field and utilizes side blowing of oxygen and inert gas for mixing in the bath. Herein, the effect of the converter inclination on mixing time and jet‐penetration length with a side‐blown physical model is investigated. Scaling with the modified Froude number is applied on data from a real industrial AOD converter to achieve a system with reasonable gas flow rates. During the experiments, water is used to simulate liquid steel and air is blown through side‐mounted nozzles for stirring. A NaCl tracer is added and subsequent conductivity measurements are used to measure mixing time. Overall, the penetration length is shown to be independent of inclination angle. The mixing time is found to be influenced by the change of bath height to diameter ratio, change of geometry in the bath volume, gas flow rate, and the intensified wave motion at the interface caused by the inclination of the vessel. The mixing time increase with 14% when 14° angle is applied.

Study of Micro/Nano Structuring and Mechanical Properties of KrF Excimer Laser Irradiated Al for Aerospace Industry and Surface Engineering Applications.

Micro/nano structuring of KrF Excimer laser-irradiated Aluminum (Al) has been correlated with laser-produced structural and mechanical changes. The effect of non-reactive Argon (Ar) and reactive Oxygen (O2) environments on the surface, structural and mechanical characteristics of nano-second pulsed laser-ablated Aluminum (Al) has been revealed. KrF Excimer laser with pulse duration 20 ns, central wavelength of 248 nm and repetition rate of was utilized for this purpose. Exposure of targets has been carried out for 0.86, 1, 1.13 and 1.27 J·cm−2 laser fluences in non-reactive (Ar) and reactive (O2) ambient environments at a pressure of 100 torr. A variety of characteristics of the irradiated targets like the morphology of the surface, chemical composition, crystallinity and nano hardness were investigated by using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffractometer (XRD), Raman spectroscopy and Nanohardness tester techniques, respectively. The nature (reactive or non-reactive) and pressure of gas played an important role in modification of materials. In this study, a strong correlation is observed between the surface structuring, chemical composition, residual stress variation and the variation in hardness of Al surface after ablation in both ambient (Ar, O2). In the case of reactive environment (O2), the interplay among the deposition of laser energy and species of plasma of ambient gas enhances chemical reactivity, which causes the formation of oxides of aluminum (AlO, Al2O3) with high mechanical strength. That makes it useful in the field of process and aerospace industry as well as in surface engineering.

Kinetics of Decarburization and Manganese Loss from Fe–15Mn–1C Alloy by Bubbling of Argon–Oxygen Gas Mixtures

Kinetics of Decarburization and Manganese Loss from Fe–15Mn–1C Alloy by Bubbling of Argon–Oxygen Gas Mixtures

Feasibility Synthesis and Characterization of Gadolinia Doped Ceria Coatings Obtained by Cathodic Arc Evaporation.

Gadolinia doped ceria coatings were elaborated by cathodic arc evaporation from a metallic Ce–Gd (90–10 at.%) target inserted into a conventional multiarc Ti evaporation target in the presence of a reactive argon–oxygen gas mixture. The structural and chemical features of these films were determined by x-ray diffraction and scanning electron microscopy. Their electrical properties were characterized using impedance spectroscopy measurements. It was shown that the as-deposited coatings crystallize in the fluorite type fcc structure of ceria and that their composition is the same as that of the target. The morphology of the coatings is influenced by the evaporation parameter (stress and droplet). The electrical measurements showed two contributions in Nyquist representation and the activation energy was slightly higher than that given in the literature data for the bulk material.

Coupled vibration-dissociation time-histories and rate measurements in shock-heated, nondilute O2 and O2–Ar mixtures from 6000 to 14 000 K

Validation of high-fidelity models for high-temperature hypersonic flows requires high-accuracy kinetics data for oxygen (O2) reactions, including time-histories and rate parameter measurements. Consequently, shock-tube experiments with ultraviolet (UV) laser absorption were performed to measure quantum-state-specific time-histories and coupled vibration-dissociation (CVDV) rate parameters in shock-heated, nondilute O2 and oxygen–argon (O2–Ar) mixtures. Experiments probed mixtures of 20% O2–Ar, 50% O2–Ar, and 100% O2 for initial post-reflected-shock conditions from 6000 to 14 000 K and 26–210 Torr. Two UV lasers—one continuous-wave laser and one pulsed laser—measured absorbance time-histories from the fifth and sixth vibrational levels of the electronic ground state of O2, respectively. The absorbance time-histories subsequently yielded time-histories for vibrational temperature (Tv) from the absorbance ratio, translational/rotational temperature (Ttr) from energy conservation, total O2 number density (nO2) from the individual absorbances, and vibrational-state-specific number density (nv″) from the Boltzmann population fractions. These state-specific temperature and number density time-histories demonstrate the low uncertainty necessary for high-temperature model validation and provide data to higher temperature than previous experiments. Additional analysis of the temperature and number density time-histories allowed inference of rate parameters in the Marrone and Treanor CVDV model, including vibrational relaxation time (τO2−O2), average vibrational energy loss (ε), vibrational coupling factor (Z), and dissociation rate constants (kdO2−O2 and kdO2−O). The results for each of these five parameters show reasonable consistency across the range of temperatures, pressures, and mixtures and generally agree with a modified Marrone and Treanor model by Chaudhry et al. [“Implementation of a chemical kinetics model for hypersonic flows in air for high-performance CFD,” in Proceedings of AIAA Scitech Forum (2020)]. Finally, the results for τO2−O2, kdO2−O2, and kdO2−O exhibit much lower scatter than previous experimental studies.

Particle Modeling of Reflected Shock Waves

A direct simulation Monte Carlo based approach is proposed to model the planar shock-wave reflection in a shock tube. The approach is validated through comparisons with available time-dependent pressure and absorbance measurements of gas relaxation behind a reflected shock in an argon–oxygen gas mixture for incident shock velocities of . It is then used to model reacting airflows for velocities , with the primary focus on the flow evolution inside the boundary layer. The feasibility of using the reflected shock configuration for the evaluation of vibrational energy accommodation, as well as the gas-phase recombination reaction rate constants, is studied. Finally, low- and high- fidelity real gas effect models are used to assess the model impact on gas macroparameters under nonequilibrium conditions.

Improvement of Seed Germination Rate, Agronomic Traits, Enzymatic Activity and Nutritional Composition of Bread Wheat (Triticum aestivum) Using Low-Frequency Glow Discharge Plasma

Plasma agriculture is an emerging field. In this report, we studied the effect of medium pressure (~ 10 torr) low-frequency (3–5 kHz) glow discharge (LFGD) plasma on various agronomical and physiological attributes in wheat. Wheat seeds treated by LFGD plasma generated from Argon–Oxygen (Ar + O2) gas mixture and air showed a remarkable enhancement in seed germination by 12.38% and 7.14% respectively. Also, the morpho-physiological features significantly improved due to plasma treatment relative to control. In germinated wheat seedlings, H2O2 concentration markedly increased due to plasma treatments, suggesting that LFGD may be involved in nitrogen signaling in wheat. The SOD activity significantly increased in wheat seedlings subjected to Ar + O2 plasma, while APX activity showed a significant increase only in the shoot of wheat plants in the same condition. Besides, both plasma treatments (Ar + O2 and Air) caused a significant increase in CAT activity in the shoot but not in the root compared to non-treated plants. Analysis of wheat plants germinated from plasma treated seeds showed a notable increase in total soluble sugar and protein subjected to Ar + O2 plasma treatment. Results also revealed a significant increase in TGM, iron, manganese, fat, and ash content while moisture content significantly decreased in wheat grain due to plasma treatments relative to controls. These findings explore the potentialities of LFGD plasma in boosting germination, growth, and nutritional traits of wheat plants.

Pressurized in situ X-ray diffraction insights into super/subcritical carbonation reaction pathways of steelmaking slags and constituent silicate minerals

This study explores mineral carbonation of industrial stainless steelmaking slags and relevant synthetic constituent minerals via in situ pressurized X-ray diffraction, to clarify carbonation reaction pathways and efficiency for carbon storage and waste valorization. The primary mineral phases of Argon Oxygen Decarburization (AOD) and Continuous Casting (CC) slags, namely, åkermanite, bredigite, cuspidine, merwinite, and β- and γ-C2S, were reacted in a custom-built beryllium-capped XRD reactor filled with either water-saturated (wet) subcritical CO2(g), or wet supercritical CO2(SC), in a series of carbonation experiments. Formation of calcite and aragonite was observed for most Ca-bearing minerals, transient precipitation of metastable vaterite was observed, while carbonation of AOD and CC slags in CO2(SC) resulted in hydrated crystalline calcium carbonates and indirect evidence of amorphous carbonate. Results obtained suggest that low-pressure subcritical carbonation routes are attractive for standalone slag carbonation processes, while high-pressure supercritical carbonation routes are amiable to symbiotic integration with CO2(SC)-generating green technologies.

Chemical Reaction and Ion Bombardment Effects of Plasma Radicals on Optoelectrical Properties of SnO2 Thin Films via Atomic Layer Deposition.

In this study, the effect of radical intensity on the deposition mechanism, optical, and electrical properties of tin oxide (SnO2) thin films is investigated. The SnO2 thin films are prepared by plasma-enhanced atomic layer deposition with different plasma power from 1000 to 3000 W. The experimental results show that plasma contains different amount of argon radicals (Ar*) and oxygen radicals (O*) with the increased power. The three deposition mechanisms are indicated by the variation of Ar* and O* intensities evidenced by optical emission spectroscopy. The adequate intensities of Ar* and O* are obtained by the power of 1500 W, inducing the highest oxygen vacancies (OV) ratio, the narrowest band gap, and the densest film structure. The refractive index and optical loss increase with the plasma power, possibly owing to the increased film density. According to the Hall effect measurement results, the improved plasma power from 1000 to 1500 W enhances the carrier concentration due to the enlargement of OV ratio, while the plasma powers higher than 1500 W further cause the removal of OV and the significant bombardment from Ar*, leading to the increase of resistivity.

Argon and Argon-Oxygen Plasma Surface Modification of Gelatin Nanofibers for Tissue Engineering Applications.

In the present study, we developed a novel approach for functionalization of gelatin nanofibers using the plasma method for tissue engineering applications. For this purpose, tannic acid-crosslinked gelatin nanofibers were fabricated with electrospinning, followed by treatment with argon and argon–oxygen plasmas in a vacuum chamber. Samples were evaluated by using scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, contact angle (CA) and X-ray diffraction (XRD). The biological activity of plasma treated gelatin nanofibers were further investigated by using fibroblasts as cell models. SEM studies showed that the average diameter and the surface morphology of nanofibers did not change after plasma treatment. However, the mean surface roughness (RMS) of samples were increased due to plasma activation. ATR-FTIR spectroscopy demonstrated several new bands on plasma treated fibers related to the plasma ionization of nanofibers. The CA test results stated that the surface of nanofibers became completely hydrophilic after argon–oxygen plasma treatment. Finally, increasing the polarity of crosslinked gelatin after plasma treatment resulted in an increase of the number of fibroblast cells. Overall, results expressed that our developed method could open new insights into the application of the plasma process for functionalization of biomedical scaffolds. Moreover, the cooperative interplay between gelatin biomaterials and argon/argon–oxygen plasmas discovered a key composition showing promising biocompatibility towards biological cells. Therefore, we strongly recommend plasma surface modification of nanofiber scaffolds as a pretreatment process for tissue engineering applications.

Study on Preparation and Ns-Laser Damage of HfO<sub>2 </sub>Single Layers

The effects of the main parameters of argon flux, oxygen flux and beam voltage on the surface morphology, transmittance spectrum and laser damage of the HfO2 single layers prepared by ion beam sputtering are studied. The HfO2 amorphous single layers have porous surface morphologies. Different processes will cause differences in coatings absorption and surface morphology, which in turn will cause changes in the spectral transmittance curve. The ion beam sputtering HfO2 single layers have high content of argon (4.5% - 8%). The laser damage of HfO2 single layers is related to argon inclusions and non-stoichiometric defects. The changes of argon flux and beam voltage have a greater impact on argon content and O/Hf ratio. When the argon content in the coatings is lower and the O/Hf ratio is higher, the laser damage thresholds of the HfO2 single layers are higher.

Modification of Leather Surface Using Low-Pressure Plasma and Antimicrobial Reagent

Investigations, which are related to plasma efficiency on the treated leather surface, are significant in the development of ecologically and economically friendly processes in obtaining material of desired functional properties. Through the pretreatments using plasma different chemical-physical reactions in the surface layer of treated leather are occurred resulting in improved reactivity. In this paper, modification and functionalization of bovine leather using 1,2,3,4-butantetracarboxylic acid and chitosan were explored. Pretreatments of leather samples were realised using argon and oxygen plasma to assess various influence of chemically reactive oxygen and inert argon gas. Two different bovine leathers -chrome tanned leather and leather tanned with synthetic tanning agent (Cr-free) were chosen for treatments. Analyse of the surface morphology was conducted with SEM microscopy, while the chemical changes using ATR-FTIR spectroscopy. Antimicrobial effectiveness of treated leather was tested with qualitative Agar diffusion plate test against two bacterial Staphylococcus aureus and Klebsiella pneumoniae. Obtained results indicated how applied oxygen and argon plasma pretreatments in optimized process conditions contribute to the improvement of tested functional properties. Achieved surface changes positively affected on leather surface reactivity and antimicrobial effectiveness, particularly Cr-free leather.

Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures

On the basis of granular synthetic zeolites NaY, HY, and ZSM-5, adsorbents containing nanoparticles of silver, cobalt, molybdenum, and tungsten were obtained. The samples have a lower surface polarity in comparison with the initial zeolites, which is reflected in the selectivity of a number of samples with respect to argon. This is due to the fact that the argon molecule interacts with zeolites only through nonspecific forces. Modification was performed by interacting with reverse-micellar solutions of nanoparticles. The actual sizes of metal particles and their distribution over the surface of the modified samples of zeolites have been determined by the method of transmission electron microscopy. The samples’ equilibrium adsorption capacities for oxygen and argon (25°С and atmospheric pressure) and the separation coefficient of the argon–oxygen mixture as the ratio of Henry’s coefficients have been determined. It has been demonstrated that samples of the NaY zeolite modified with silver nanoparticles have the separation coefficient value of the argon–oxygen gas mixture equal to 1.6.

Effect of the Ni2+/Ni3+ Concentration on the Optoelectronical Properties of Lithium-Doped Nickel Oxide Films

Lithium-doped nickel oxide (LNiO) films were prepared through radio-frequency magnetron sputtering. The optoelectronic and structural properties of the LNiO films were investigated with respect to varying ratios of argon–oxygen (Ar/O2) and argon–hydrogen (Ar/H2) reaction gases. The resulting LNiO films were polycrystalline, displaying a NaCl-type structure with a grain orientation in the (111) and (200) directions. An increase in the Ni3+ electron bonding states led to a decrease in the resistivity of the LNiO films under the Ar/O2 reaction gas. Nevertheless, the Ni3+ ions in LNiO films induced brown or black coloration and a decrease in transmittance. The high-transmittance LNiO films were deposited with varying ratios of Ar/H2 as the reaction gas. However, the generation of OH bonds promoted the adsorption of water molecules. The electrons provided by the adsorbed water molecules on the LNiO film reduced the number of Ni3+ ions, and this reaction reduced the carrier concentration and resistivity of the film. Therefore, the LNiO/Ag/LNiO multilayer structure with top and bottom LNiO films deposited with the Ar/H2 reaction gas exhibited impressive resistivity and transmittance.

Kinetics of Reaction of Oxygen with Uranium(IV) Chloride in Alkali Chloride Melts

Alkali chloride melts have numerous potential applications in nuclear fuel cycle including pyrochemical reprocessing of spent nuclear fuels, uranium electrowinning and electrorefining. Oxygen is a common technological impurity that can affect uranium speciation and behavior in fused salts. The present work was devoted to studying the reactions of oxygen with solutions of uranium tetrachloride in molten alkali chlorides. The experiments were performed in LiCl–KCl, NaCl–KCl–CsCl and NaCl–CsCl eutectic based melts at 450–750 oC. Pure oxygen and argon–oxygen mixtures (containing ca. 1 and 10 % O2) were used. Amount of oxygen passed through the melt varied from less than one to over 100 moles per mole of uranium present. Effect of moisture (0.4–2.5 % H2O) presence in oxygen or Ar–O2 mixtures was also investigated. The course of the reaction was followed by in situ electronic absorption spectroscopy measurements with the spectra recorded at the certain time intervals.Depending on temperature, cationic melt composition and oxygen-to-uranium molar ration the reaction resulted in oxidation of uranium(IV) to soluble uranyl chloride and/or precipitation of uranium dioxide. Analysis of the spectra provided the information on kinetics of U(IV) concentration change. Increasing temperature, O2 : U(IV) molar ratio or decreasing mean radius of alkali cations of the solvent melt resulted in faster decrease of U(IV) concentration in the melt.Under certain conditions U(IV) can be oxidized to UO2Cl4 2– without precipitation of UO2. Therefore sparging the melt with oxygen can be used as a way of separating uranium from certain fission products, for example rare earth elements. Rare earth chlorides react with oxygen yielding oxychlorides or oxides insoluble in alkali chloride melts. Interaction of oxygen with melts containing a mixture of uranium and rare earth chlorides was therefore also investigated and an example of the spectra recorded in LiCl–KCl–UCl4–NdCl3 melt is shown in Fig.Fig. Spectra recorded in the course of reaction of O2 with LiCl–KCl–UCl4–NdCl3 melt at 550 oC. Arrows show the direction spectra changed. Figure 1

A Review of the Influence of Steel Furnace Slag Type on the Properties of Cementitious Composites

The type of steel furnace slag (SFS), including electric arc furnace (EAF) slag, basic oxygen furnace (BOF) slag, ladle metallurgy furnace (LMF) slag, and argon oxygen decarburization (AOD) slag, can significantly affect the composite properties when used as an aggregate or as a supplementary cementitious material in bound applications, such as concretes, mortars, alkali-activated materials, and stabilized soils. This review seeks to collate the findings from the literature to express the variability in material properties and to attempt to explain the source(s) of the variability. It was found that SFS composition and properties can be highly variable, including different compositions on the exterior and interior of a given SFS particle, which can affect bonding conditions and be one source of variability on composite properties. A suite of tests is proposed to better assess a given SFS stock for potential use in bound applications; at a minimum, the SFS should be evaluated for free CaO content, expansion potential, mineralogical composition, cementitious composite mechanical properties, and chemical composition with secondary tests, including cementitious composite durability properties, microstructural characterization, and free MgO content.