Inert Gas Pressure Research Articles

Tailoring Li assisted CZTSe film growth under controllable selenium partial pressure and solar cells.

It is still critical to prepare a high-quality absorber layer for high-performance Cu2ZnSnSe4 (CZTSe) multi-component thin film solar cell. The gas pressure during the selenization process is commonly referred to as the pressure of inert gas in the tube furnace, while the exact selenium partial pressure is difficult to be controlled. Therefore, the grain growth under different selenium partial pressures cannot be made clear, and the film quality cannot be controlled as well. In this work, we use a sealed quartz tube as the selenization vessel, which can provide a relatively high and controllable selenium partial pressure during the selenization process. To further tailor the grain growth, lithium doping is also utilized. We find that lithium can greatly promote the growth of CZTSe films as the selenium partial pressure is controlled near the selenium saturation vapor pressure. Combined with ALD-Al2O3, the crystallization quality of CZTSe absorber films is significantly enhanced and the efficiency of CZTSe solar cells achieved a significant improvement. This work clarifies the effect of controllable Se pressure on CZTSe film growth and can lead to better results in CZTSe and other multi-compound thin film solar cells.

Enhanced hydrogen degradation of two pipeline steels by increasing inert gas pressure in hydrogen-containing mixtures: experimental and theoretical insights

This study highlights the significant role of total gas pressure in enhancing hydrogen degradation in hydrogen/inert gas mixtures. Tests were performed to measure the fatigue crack growth rate (FCGR) of X80 and GB20# pipeline steels in pure hydrogen and hydrogen/nitrogen blends. Findings showed that FCGR increased in the blend with elevated total gas pressure relative to pure hydrogen, despite an equivalent hydrogen partial pressure between the two environments. First-principles molecular dynamics (FPMD) calculations revealed that the increased number of nitrogen molecules within the Fe-H2-N2 systems promoted the movement velocity of hydrogen and premature dissociation of hydrogen.

Phenomenological Study of the Atomization Process in Pre‐Filming Nozzles Typically Used for Steel Atomization

Liquid steel atomization using close‐coupled nozzles is highly dependent on the relationship between momentum flux ratio, gas–liquid ratio, aspiration pressure, and operating pressure of inert gases. A strong correlation between these parameters and the final powder must be assumed. Understanding these parameters, their influence on the process, and their interactions with each other is indispensable for efficient powder production. In particular, the industrial application of close‐coupled atomization nozzles, which develop a thin pre‐film on the nozzle tip, is not yet fully understood. A model experiment is presented to investigate interactions between the flow conditions of the gaseous and liquid phases, focusing on recirculation phenomena inside the atomization zone. The experiments show the influence of liquid and gas flow conditions on the spray geometry and the liquid core length, as well as the strong dependence of the liquid mass flux on the gas flow. The aspiration pressure below the liquid nozzle is sensitive to gas pressure and has a major influence on the development of the liquid core and the pre‐film, as it increases the liquid mass flux. For practical application, the results confirm an optimal operating point of interacting system parameters, which leads to high‐quality atomization with minimal use of resources.

Solution combustion synthesis of iron-based magnetic nanoparticles: influence of inert gas pressure

We report the synthesis of iron oxide nanoparticles using solution combustion synthesis, focusing on the controlled manipulation of material characteristics, such as particle size, phase composition, and magnetic properties, by applying external inert gas pressure. It was shown that variation of nitrogen gas pressure in the reactor in the range 0.1 to 1.1 MPa changed the time-temperature history of the process and resulted in the gradual change of phase composition of the fabricated materials along the FeO → FeO∙Fe2O3 → Fe2O3 route. The particle size varied in the 50–400 nm range, with a maximum for powder synthesized at a pressure of 0.25 MPa. For magnetic fluid hyperthermia, the critical parameter is specific loss power. It was demonstrated that this parameter can be optimized by gas pressure variation. The maximum specific loss power measured under conditions suitable for magnetic hyperthermia (magnetic field 33.5 mT and frequency 259.6 kHz) appears to be 174 W/g. The proposed innovative approach is an effective tool for controlling the synthesis of various nanoparticles with desired properties.

Analysis of the effect of inert gas on alveolar/venous blood partial pressure by using the operator splitting method.

This study aims to investigate how inert gas affects the partial pressure of alveolar and venous blood using a fast and accurate operator splitting method (OSM). Unlike previous complex methods, such as the finite element method (FEM), OSM effectively separates governing equations into smaller sub-problems, facilitating a better understanding of inert gas transport and exchange between blood capillaries and surrounding tissue. The governing equations were discretized with a fully implicit finite difference method (FDM), which enables the use of larger time steps. The model employed partial differential equations, considering convection-diffusion in blood and only diffusion in tissue. The study explores the impact of initial arterial pressure, breathing frequency, blood flow velocity, solubility, and diffusivity on the partial pressure of inert gas in blood and tissue. Additionally, the effects of anesthetic inert gas and oxygen on venous blood partial pressure were analyzed. Simulation results demonstrate that the high solubility and diffusivity of anesthetic inert gas lead to its prolonged presence in blood and tissue, resulting in lower partial pressure in venous blood. These findings enhance our understanding of inert gas interaction with alveolar/venous blood, with potential implications for medical diagnostics and therapies.

Study on physical explosion equivalent of large diameter and high pressure natural gas pipeline

High pressure natural gas pipelines are prone to material failure and explosion due to various reasons. Over the years, scholars have done in-depth research on the process of chemical explosion. In this paper, the energy components of high-pressure trunk natural gas pipeline under normal operation state were derived. Based on the assumption of adiabatic non isentropic, the pressure distribution in the pipeline within a period of time after the pipeline cracks was derived, and the energy released by the physical explosion of the pipeline was further derived. To verify the theoretical results, an original size pipe explosion experiment was organized, and the pressure distribution obtained from the experiment was found to be in good agreement with the theoretical calculation results. Through the crack propagation time and the duration of ground motion obtained from the experiment, the range of the duration of the pipeline burst crack impact was obtained, and the equivalent range of the pipeline explosion was further calculated. At the same time, through the regression analysis of ground motion, the equivalent of the pipe explosion in this experiment was about 177 kg TNT, which was consistent with the theoretical results. Further, the theoretical model and experimental results were verified by numerical simulation, and deeply studied the influence factors of buried depth on the explosion equivalent, as well as the relationship between the environment of the pipeline and the explosion damage mode and hazard range of the pipeline. The research results of this paper give the calculation method and magnitude range of physical explosion equivalent of high-pressure trunk natural gas pipeline. It provides a reference for the formulation of safety standards for high-pressure trunk natural gas pipelines and inert gas pressure vessels.

Precision black body model at a temperature of 200–450 K:metrological ensurance for optical-electronic equipment for remote sensing of the Earth in the infrared range of the spectrum

The issues of radiometric calibration of optical-electronic equipment for remote sensing of the Earth in a wide range of spectral radiance have been studied. An alternative method for transmitting a spectral radiance unit from a reference source at the phase transition temperature of pure metals to optical-electronic equipment for remote sensing of the Earth in the infrared wavelength range above 2.5 μm is presented. The method is based on the stepwise transfer of a spectral radiance unit from a reference source through a precision model of a black body with a high level of emissivity and a wide temperature range identical to the temperature range of a wide-aperture black body model with a range of spectral radiance required for calibrating optical-electronic equipment for remote sensing of the Earth. A precision black body model PMBB-60m with an output aperture with a diameter of 30 mm was developed, studied and calibrated in the temperature range of 200–450 K. The calculated value of the effective emissivity of PMBB-60m with coating of the cavity by Aeroglaze Z306 paint is 0.9997. The composition and design of PMBB-60m are described. PMBB-60m can operate both in vacuum conditions and in conditions of inert gas or atmospheric pressure. The metrological characteristics of PMBB-60m , obtained by transferring a temperature unit from the State Standard of the zero digit of a temperature unit in the range from 0 to 3000 °C using a comparator, based on a precision pyrometer TRT II (Heitronics Infrarot Messtechnik GmbH, Germany) are presented. The correction to the PMBB-60m temperature readings in the temperature range of 223.15–450.15 K did not exceed 39 mK according to the results of calibration in the temperature range of 223.15–450.15 K. The results of calculating the expanded uncertainty in the temperature range of 223.15–450.15 K did not exceed 1 K. The values of instability of temperature maintenance PMBB-60m, measured in steps of 10 s for 15 minutes, did not exceed 15 mK in the considered temperature range. The results of calculation of the spectral effective emissivity of PMBB-60m, carried out using the STEEP3 program, are presented.

LIBS plasma in atmospheric pressure argon, nitrogen and helium: Spatio-temporal distribution of plume emission and Hα linewidth

Laser Induced Breakdown Spectroscopy (LIBS) method is considered for assessing the retention of hydrogen isotopes in the ITER plasma-facing components during the maintenance breaks when the reactor is filled with near atmospheric pressure nitrogen or inert gas. At these conditions, the broadening of the spectral lines of hydrogen isotopes and the reduction of line intensities complicates the distinguishing of hydrogen isotopes. The aim of the present study was to investigate the effect of atmospheric pressure nitrogen, argon and helium ambient gas on the spatio-temporal distribution of the LIBS plasma plume emission and linewidths of Hα line, representing the hydrogen isotopes. Nd:YAG laser with 8 ns pulse width was used to ablate the molybdenum (Mo) target with hydrogen impurity. The development of the formed plasma plume was investigated by time and space-resolved emission spectra in the 20 nm range around the 656.28 nm Hα line. For all gases used in the experiments, the intensity and linewidth of Hα line decreased with the delay time between the laser pulse and the spectral registration. At the same linewidth values, the highest intensities were obtained in the helium atmosphere while the lowest intensity was obtained in nitrogen. According to spatially resolved spectral measurements, the Hα line was most intense near the Mo target while the Mo lines peaked farther away. In the case of the helium atmosphere, the plasma plume emission was observed at a longer distance from the target and it decayed faster than in argon and nitrogen atmospheres. According to these results, helium is the most beneficial ambient gas for hydrogen isotope detection by atmospheric pressure LIBS. The use of argon ambient gas may be required when LIBS is used for the simultaneous determination of fuel and He retention in the wall material.

Rheological, Ballistic, and Mechanical Properties of 3D Printed, Photocured Composite Propellants

This study explores the rheological, mechanical, and ballistic properties of printed ammonium perchlorate composite propellant at 82.5% solids loading with binders curable with ultraviolet light of wavelength from 215 to 400 nm (UV). A polybutadiene urethane acrylate and two polyester urethane acrylate propellants are printed by an in-house-fabricated fused deposition molding printer. Propellants are all shear-thinning and have significantly lower viscosity than similar hydroxyl-terminated polybutadiene (HTPB) propellants. Uniaxial stress–strain measurements indicate that ultimate tensile strength and ultimate tensile strain of all photocurable propellants are found to be greater than HTPB propellant. In particular, the ultimate tensile strain of polyester urethane acrylate propellant is six times that of HTPB propellant, demonstrating high compliance. Ballistic properties are measured from combustion of printed propellant articles in a windowed Crawford combustion bomb at inert gas pressures of up to 12.1 MPa. The burning characteristics were found to be relatively planar, though strong burning rate anisotropy, expected as a result of print layer inhomogeneities, was observed in two of the three formulations. Overall, pressure exponents of the propellants were mild and ranged from 0.17 to 0.33. These results are compared and contrasted to those of other printed propellants. These results provide valuable insight into the selection of a safe binder system for printing of photocurable composite propellants.

Enhanced hydrogen embrittlement of steel by the premature hydrogen dissociation with the increasing inert gas pressure in hydrogen-containing mixtures

Regarding hydrogen embrittlement (HE) in the mixtures of hydrogen and inert gas, the results were understood mainly based on the partial hydrogen gas pressure. On the other hand, the effect of the total gas pressure has not been fully investigated. In this study, fatigue crack growth rate (FCGR) tests were conducted in high-purity hydrogen gas at different gas pressures. Also, the FCGR tests were conducted in hydrogen and nitrogen mixtures at different total gas pressures. The hydrogen partial pressure in the mixture was the same as the high-purity hydrogen. This was the first time that acceleration of the FCGR in the mixtures compared to that in the high-purity hydrogen was observed. To elucidate the mechanism of the enhanced HE in the mixtures, hydrogen permeation and hydrogen desorption experiments were carried out. Based on the results of these tests, the acceleration of the FCGR in the mixtures could be interpreted by the fast hydrogen entry rate, which may result in a higher local hydrogen concentration near the crack tip during a limited time. Density functional theory (DFT) calculations were performed to consider the total gas pressure effect on an atomic scale. The thrust force of other gas molecules in the mixtures made the hydrogen molecules enter the potential field of the iron surface sooner, advancing the dissociation of the hydrogen. This will increase the surface concentration of the hydrogen atoms.

From tetroses to methionine hydroxy analogues through Sn (IV) Lewis acid catalysis using methanethiol as sulphur feedstock

Methionine hydroxy analogues (MHAs) form part of a million tonne scale commodity market of compounds useful in livestock nutrition. The chemocatalytic synthesis of MHAs from carbohydrates is an important albeit understudied transformation en route to a sustainable and circular economy. Here we report our first results for the conversion of tetroses to MHAs in the presence of methanethiol (MeSH) and SnCl4·5H2O. Our study allowed to corroborate the major reaction pathways involved in this Lewis acid-catalysed transformation. It was also found that the ratio between MeSH and MeOH, the pressure of inert gas, and the water content strongly affect the reaction performance. When these parameters were combined the yield and selectivity towards MHAs increased to the highest reported value of 38 % in one hour reactions at 413 K. Our findings have the potential to unlock the sustainable synthesis of MHAs from renewable feedstock such as tetroses and other carbohydrates.

Lithium Separation from Geothermal Brine to Develop Critical Energy Resources Using High-Pressure Nanofiltration Technology: Characterization and Optimization.

There is a shift from internal combustion engines to electric vehicles (EVs), with the primary goal of reducing CO2 emissions from road transport. Battery technology is at the heart of this transition as it is vital to hybrid and fully electric vehicles' performance, affordability, and reliability. However, it is not abundant in nature. Lithium has many uses, one of which is heat transfer applications; synthesized as an alloying agent for batteries, glass, and ceramics, it therefore has a high demand on the global market. Lithium can be attained by extraction from other natural resources in igneous rocks, in the waters of mineral springs, and geothermal brine. During the research, geothermal brine was used because, from the technological point of view, geothermal brine contains higher lithium content than other resources such as seawater. The nanofiltration separation process was operated using various solutions of pH 5, 7, and 10 at high pressures. The varying pressures are 11, 13, and 15 bar. The nanofiltration method was used as the separation process. High pressure of inert nitrogen gas was used to supply the driving force to separate lithium from other ions and elements in the sample. The research results supported the selected parameters where higher pressure and pH provided more significant lithium recovery but were limited by concentration polarization. The optimal operating conditions for lithium recovery in this research were obtained at a pH of 10 under a pressure of 15 bar, with the highest lithium recovery reaching more than 75%.

Пористость консолидированных методом газовой экструзии компактов из никелевых нанопорошков

The method of hot gas extrusion differs from other methods of metal pressure treatment in that the processed material is subjected to intense plastic deformation by extrusion under conditions of high isostatic pressure of inert gas and heating in the area of plastic deformation. The method makes it possible to process powder materials, while inevitably there is a need to control mechanical properties by controlling porosity and pressure inside the pores. The paper presents a method for calculating the pressure inside the pores from the minimum size of the closed pore. The pore pressure was evaluated on materials obtained by the consolidation of nickel nanopowders by hot gas extrusion. Quantitative processing of the material cross-section view images obtained by scanning electron microscopy showed that the minimum pore size is 220 nm. The formula for calculating the pore pressure is derived from the formula for calculating the critical pore radius. It takes into account the external impact pressure (the gas pressure during the extrusion process was equal to 400 MPa), the surface tension coefficient and the yield strength of nickel (at the extrusion start temperature of 910 °С), as well as the minimum pore radius. The proposed method for calculating the pressure inside a closed pore will allow us to evaluate the mechanical properties of materials obtained by various methods of powder metallurgy.

Investigation of the Liquefaction Kinetics of the PolyE-IL-Catalyzed Catalytic Thermo Liquefaction Process for Organic Biodegradable Municipal Solid Waste

The catalytic thermo liquefaction (CTL) process with integration of the PolyE-IL catalyst has the specific advantages of high conversion, no char production, and nonstringent operating conditions. However, the study of the liquefaction kinetics is one of the most important parameters to elucidate the mechanism of the CTL process and a guide for process scale-up. The present manuscript demonstrates the elucidation of the liquefaction kinetics of a PolyE-IL-catalyzed CTL process for CTL of organic biodegradable waste. The CTL for different feedstocks showed >80% feed conversion at 120 °C in 120 min and under 10 bar inert gas pressure. Thus, both pressure and reflux reaction condition approaches for CTL were followed to investigate prevailing reactor parameters for liquefaction. However, the influences of reactor operating conditions with variable MSW slurry concentrations, temperatures, and times were inspected. The lower slurry concentration (<3 wt %) did not show the effect of the mode of operation, but the efficacy of liquefaction was reduced in the reflux mode of operation at a higher slurry concentration (<5 wt %). The reaction temperature of >90 °C was found to be efficient to achieve a maximum conversion, 75 and 70% at pressure and reflux modes of operation, respectively. Moreover, it was observed that a reaction time of at least 10 min was sufficient to achieve at least 75% conversion, although a longer reaction time increased the degree of liquefaction. According to liquefaction behavior of MSW, the plausible reaction routes were proposed. The first-order reaction was shown in the kinetic analysis to have an activation energy of 411.5 J/g and a frequency factor of 9.3 min–1. The lowest contact time was advantageous for increased liquefaction of MSW. Thus, the present study offers an in-depth understanding of the CTL reaction pathways and the liquefaction kinetics, which can be useful for developing scalable and economically viable CTL processes.

A self-powered inert-gas sensor based on gas ionization driven by a triboelectric nanogenerator

Inert gases play an important role in fabrication technologies and human life activities. However, normal gas-detection methods have many limitations on the costs and operation to detect inert gases since inert gases have extremely inactive chemical properties. In this paper, a self-powered inert-gas sensor based on gas discharges induced by a rotating triboelectric nanogenerator (TENG) with a needle discharge structure is developed. The friction layers of the rotating TENG are optimized to generate a high-voltage output with a sufficient pulse width for gas ionization in the high electric field formed between the small gap of two needle tips. Because different inert gases have different ionization characteristics, the type, pressure, and concentration of inert gases can be distinguished from TENG voltage gains during ionization. The experimental results indicate that, at standard atmospheric pressure, the gain of the TENG open-circuit voltage is 250% when ionizing air, 330% for ionizing argon, and 180% for ionizing helium. When ionizing a specific gas, both a decrease in pressure and an increase in concentration result in an increase in open-circuit voltage gain. Based on correlation between the types, pressure and concentration of gas and the output performance of TENG, the inert gas sensor with simple operation and high efficiency can be realized. The proposed inert gas sensor is simple, low cost and self-powered, which has potential applications in the field of industry and the Internet of Things (IoT).

Research on the wood processing method of helium-assisted laser process

In order to promote the development of environmental protection, and the usage rate of green energy utilization, a progressive, innovative laser process method employing helium assisted is proposed, which optimizes the joint cutting process under the same energy consumption. This method provides a new idea for the wood process industry. The uniqueness of this paper establishes a mathematical model to address the diffusion of helium injection and the heat transfer of the laser beam on the processed surface. From the results, it can be exhibited that the oxygen concentration reduces when the helium is injected on the processed surface. The helium could destroy the combustion-supporting conditions and decrease the combustion zone of the processed joint cutting. Thus, the carbonized area of the processed surface is reduced, which could effectively enhance the processing quality of joint cutting. Notably, the helium with injection speed forms a sweeping effect on the processed surface, which could remove parts of the carbonized particles and residues on the processed surface, as well as improve the processing quality. Comparing the traditional laser process and helium-assisted laser process, the gas-assisted laser process owns higher process quality than that of traditional laser processing and cutting. In detail, it features the advantages of smaller joint cutting width, lower surface roughness and smoother surface. Eventually, a mathematical model based on the response surface method with the evaluation criteria of the kerf width, kerf depth, and surface roughness is established to analyze the interaction of laser power, cutting speed and inert gas pressure on the response factors. Comparing the error between the predicted and experimental measurement value, and the optimized process parameters could be acquired. In this paper, the helium-assisted laser process method proposed is meaningful and encouraging, which not only obtains better processing quality, but also provides a guide for developing green industry.

Influence of the Inert Gas Pressure on Intrinsic Stress in Diamond-Like Coating Deposited From Vacuum Arc Carbon Plasma

Within the framework of the model of the nonlocal thermoelastic peak of low-energy ion, the formation of intrinsic stress in a carbon coating deposited from the vacuum arc plasma in the argon atmosphere is theoretically studied. It is shown that the flow of particles bombarding the deposited coating contains, along with C+ ions, also Ar+ ions involved in the formation of intrinsic stress in the coating. The flux density of Ar+ ions resulting from ionization losses of C+ ions passing through the argon atmosphere is proportional to both the flux density of C+ ions and the density (pressure) of argon. Expressions are obtained for the intrinsic stress in the deposited carbon coating depending on the bias potential on the substrate and the argon pressure for the cases of both constant and pulsed potentials. The analysis of the obtained expressions shows that the intrinsic stress in the carbon coating decrease with increasing argon pressure.

Optimization of growth parameters to obtain epitaxial large area growth of molybdenum disulfide using pulsed laser deposition

2D transition metal dichalcogenides (TMDCs) are promising materials for device applications owing to their electronic, optical, and material properties varying with the number of monolayers. Synthesis of large area crystalline TMDC thin films is still challenging with techniques such as exfoliation and chemical vapor growth owing to the uncontrollability of deposition area and high temperature growths with toxic precursors, respectively. Pulsed laser deposition (PLD) is a technique that can overcome these challenges owing to stoichiometric layer by layer growth control by optimizing the growth parameters. In this study, we optimize parameters such as temperature, post-growth annealing, inert gas pressure, and substrate–target distance during PLD growth of MoS2 to obtain uniform and highly crystalline thin films on an ∼1 in.2 substrate. The optimized growth conditions are 800 °C with a 30 min post-growth annealing at a laser fluence of 2.2 J/cm2 with a substrate–target distance of 5 cm and 0.5 mTorr of argon partial pressure. An RMS roughness of 0.17 nm was obtained for 3 nm (4 monolayers) thick MoS2 films with a thin film conductivity of ∼4000 S/m.

Analysis of the Morphology of the Growth Interface as a Function of the Gas Phase Composition during the PVT Growth of Silicon Carbide

The growth conditions of 75 mm SiC crystals in the PVT process is varied by different methods while the temperature field is kept constant. The addition of graphite into the source material leads to the formation of an ordered step flow with step heights of 0.014 µm, while the addition of graphite into the source together with N2 doping changes the step kinetics on the main facet, leading to very large, bunched steps of 0.17 µm. When elemental Si was added into the source material large macro steps are formed on the whole crystal surface. While the doping induced step bunching is related to the incorporation kinetics, the large steps induced in Si-rich conditions are attributed the reduction of surface energy. With the variation of the inert gas pressure the morphology of the surface is altered, similarly. Under low pressure conditions (0.2 mbar) a fine step structure evolves, while at a high pressure (40mbar) large surface steps are formed on the whole growth interface. Large surface steps are strongly impeded in their lateral motion at defects permeating the growth interface. At these sites the formation of foreign polytypes is facilitated.

Unraveling the influence of dissolved gases on permeate flux in organic solvent nanofiltration – Experimental analysis

The first step in quantifying the performance of organic solvent nanofiltration membranes are usually lab-scale experiments with respect to flux and rejection. The necessary pressurization of the feed is either realized mechanically by a high-pressure pump or by means of a pressurized inert gas. While the latter option is most frequently applied, the gas may dissolve in the feed mixture and permeate through the membrane, affecting the transport of the other components. This potential effect is commonly neglected, inherently assuming that the gas solubility is negligible. The current study provides a systematic experimental investigation and analysis of the impact of dissolved gases on solvent flux for a hydrophilic DuraMem membrane, with gas solubilities assessed through PC-SAFT. The results prove that a gas with low solubility has a negligible effect on the solvent flux. In contrast, an increasing gas solubility may result in significant gas flux through the membrane with a considerable effect on the solvent flux. Furthermore, the correlation of the solvent flux with the gas solubility in the feed mixture is strongly non-linear. Therefore, gas solubility is recommended to be critically evaluated when conducting OSN experiments, specifically considering the final application. In that context, the permeation of dissolved gas has to be actively accounted for in OSN experiments for gas–liquid systems.