Argon Content Research Articles

Effects of sputtering gas on microstructure and tribological properties of titanium nitride films

Abstract Titanium nitride (TiN) films can be utilized as hard and protective coatings for synchronizer ring, which is the key components of the car gearbox. The tribological properties of synchronizer ring play a key role in the safety and reliability of the car shifting system. The aim of the present work is to improve tribological properties of synchronizer ring and investigate effects of depositing gas on preferred orientation, surface morphology, surface roughness and tribological properties of TiN thin films. The as-prepared films are deposited on copper alloy (TL084) and Si (100) substrates by a closed field unbalanced magnetron sputtering system. The different sputtering gas with the volume ratio of argon to nitrogen of 1:3, 1:2 and 1:1 is employed. Results indicated that the increasing argon concentration in the gas mixture promotes the growth of TiN nanocrystallines and reduces its surface roughness, friction coefficient and wear rate. TiN films have the (200) preferred orientation at low argon concentration, while the (111) preferred orientation dominates at high argon concentration. TiN thin films deposited with the ratio of argon to nitrogen of 1:1 has the best tribological properties, which are the best sputtering condition as an ideal functional coating for synchronizer ring.

Residence time distribution measurements for model flows based on laser-induced breakdown spectroscopy

A method of measuring the residence time distribution (RTD) of flow is proposed using laser-induced breakdown spectroscopy (LIBS) with an argon tracer. As a proof-of-concept study, the method is applied to measure the RTDs of two flow devices that mimic a plug flow tube and a well-stirred vessel at cold (non-reacting) conditions. Argon emission lines are first observed to avoid interference with the lines of carbon, hydrogen, oxygen, and nitrogen and their areas are calibrated to provide the argon concentration. Argon is injected to the air stream as a Heaviside (step) function, and the RTDs are obtained by differentiating the temporal changes in the argon concentration traced using LIBS. The method is expected to be used for designing reactors and validating the results of numerical studies.

A determination of atmospheric helium, neon, argon, krypton, and xenon solubility concentrations in water and seawater

We have determined the concentrations of atmospheric helium, neon, argon, krypton, and xenon in distilled water and seawater equilibrated with moist marine air at one atmosphere over a temperature range from near freezing point to approximately 35 °C and a salinity range of zero to roughly 39.5 PSS78. In all, we made 74 sets of noble gas measurements at 34 distinct temperature and salinity combinations. The experiments included 35 replicate pairs of samples drawn from 35 separate equilibrations, which in turn had three pairs of repeat equilibrations run at close to identical temperatures. We fit the results to an eight-parameter function similar to one commonly used to compute solubility equilibrium concentrations of these gases for environmental waters. Based on an estimate of analytical accuracy, reproducibility of the comparison with secondary atmospheric standards, replicate sample reproducibility, and reproducibility of the repeat equilibrations, we estimate this function to predict equilibrium concentrations at a particular temperature and salinity within this range to overall precisions 0.10% or better. This includes the regression statistics associated with interpolation and analytical errors for fitting the 8-parameter smoothing function. There is an overall systematic uncertainty of 0.15% for all gases, based on our confidence in and experience with the integrity and cross-calibration of our air standards over recent years. Because our methods are calibrated using assumed and explicit atmospheric abundances of these noble gases, any subsequent uncertainties in atmospheric abundances cancel out in the determination, particularly when the oceanographic measurements utilize marine air as a primary standard. Furthermore, measurement at ambient atmospheric abundances avoids any potential co-solvency induced biases introduced by using ~1 atm pure noble gases, as has been done in most previous studies. We compare these determinations to those made by others in the past and find modest but significant systematic differences with those results.

Effect of shielding gas flow on welding process of laser-arc hybrid welding and MIG welding

The influence of shielding gas on welding process of laser-arc hybrid welding (LAHW) and metal inert-gas welding (MIG) was investigated by the computational fluid dynamics analysis (CFD) and high-speed photography. The results show that the process stability of MIG under high gas flow rate is poorer than that of LAHW. And the force of gas flow Fg can hinder the droplet transfer, whether MIG or LAHW. But the vaporization-induced recoil force Fv in LAHW helps to reduce this kind of hindrance and keep the process stability. Next, it can be found that the shielded gas flow mode in the main welding area cannot be changed significantly by increasing the shielding gas flow rate, while high gas flow rate can increase the area of high argon concentration and benefit the spread of molten metal.

ПРИСТРІЙ ЕКСПРЕС-КОНТРОЛЮ ЯКОСТІ ЕНЕРГОЗБЕРІГАЮЧИХ СКЛОПАКЕТІВ

Urgency of the research. It is known that to reduce the thermal conductivity fill with argon, which has low thermal conductivity, under atmospheric pressure inside a double-glazed window, and according to State standard of Ukraine [1] the air content in a double-glazed window should not exceed 15%. Since over time, part of the molecules of argon is replaced by molecules of air, thus deterioration of the thermal insulation properties, which leads to energy and financial losses. Therefore, there is a need to check the concentration of argon in the glass units. Target setting. An important task is to produce available devices for express control quality of energy saving doubleglazed windows. The principle of operation of the device is based on the fact that the electrical strength of air in conditions close to normal is approximately 1.6 times greater than that of argon. Replacing part of the molecules of argon with air molecules leads to an increase in the breakdown potentials difference. Actual scientific researches and issues analysis. In recent studies of methods for checking the concentration of argon in a double-glazed, it is proposed to use methods of spectral analysis, as well as physical methods of analysis, which include electrochemical processes. Among them, the GASGLASS V2 device, which can check the composition of the gas contained in the double-glazed unit, but the indicated device has a high cost (7900 €) and is difficult to use. In addition, the quality of double-glazed windows is estimated according to the method described in in State standard of Ukraine. Uninvestigated parts of general matters defining. Thus, for the use of the device proposed by us, it is necessary to know the dependence of the electrical strength of the mixture of argon and air on the concentration of air. The formulation of the problem. Conduct research on the dependence of the electrical strength mixture of the argon and air to the concentration of air, and offer a model of a simple and affordable device for concentration of argon in the double-glazed unit. The statement of basic materials. To carry out an experimental study, we assembled an installation that includes a vacuum plate, a vacuum pump, an electroforming machine, an arrester, a voltmeter, and a balloon filled with argon. During the experiment, with the help of a caliper, it was established at which the smallest distance was the spark electrical discharge between the discharge bullets of the electroforming machine and measured the discharge voltage. It should be noted that the spark discharge between the balls of the electroforming machine occurred at a much lesser distance, than between the bullets of the arrester, which placed under the lid of the vacuum plate with argon. In total, 6 series of experiments were conducted for different concentrations. According to the data, a graph of the dependence of electrical strength on the concentration of air in argon, which can be used to calibrate the unit for assessing the quality of the double-glazed windows, was constructed. The structure and principle of the device for controlling the concentration of argon have been analyzed. It was determined that the device should contain the following parts: contact electrodes, indicator of current, a button for launching a high-voltage generator, electric discharger and the stabilizer AMS1117-3.3. Conclusions. During the experiment, the dependence of electrical strength in real-time was established with the help of theoretical and experimental research on the developed methodology, using the installation for the experiment. Also, the dependence of the spark discharge on the concentration of argon on the graph was plotted.

Diffusion of Ar atoms implanted in a TiO2 matrix studied with Temperature Programmed Out-Diffusion✰

The diffusion of noble gas argon in the near-surface region of rutile TiO2 has been explored with the Temperature Programmed Out-Diffusion (TPOD) method. The Ar atoms were deposited in a several-nanometer-deep layer of the single-crystal TiO2(110) surface by bombardment with 1–5 keV energy Ar ions. Subsequently, in the TPOD experiments this sample was heated at a linear rate and the out-diffusion of argon was monitored with a mass-spectrometer. Surface conditions were probed with Auger Electron Spectroscopy (AES) and Low-Energy Electron Diffraction (LEED). The experimental results were analyzed with the aid of numerical simulations. The measurements showed a dependence of the Ar diffusion rates on the concentration of buried argon and composition of the surface layer. The kinetic parameters of Ar diffusion in pristine rutile TiO2 were estimated as Ea = 104 kJ/mol and D0 = 6 ⋅ 10−9 m2/s. A distinctive diffusion regime, related to the rock salt TiO phase formation, were identified.

The Influence of Ar on the Synthesis of Carbon-coated Copper Nanoparticles in Gaseous Detonation

Background: Carbon-coated metal nanoparticle is a kind of unique nuclear-shell material that is the carbon shell filled with metal particles. It has a great promising future in the application as excellent solid lubricants additives, conducting resin, antiradiation material and so on. As a mature technology, the gas detonation method has been widely used to synthesize various nanomaterials. Method: Using copper acetylacetonate as a precursor to provide carbon and different concentrations of argon as a protective medium for the first time, high quality carbon-coated copper nanoparticles (Cu@C) were synthesized in hydrogen and oxygen. X-ray Diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) were employed to characterize the structure, phase and constituent of the Cu@C nanoparticles to investigate the influence of argon concentration on the synthesis. Results: The XRD pattern, Raman spectroscopy and TEM images confirm the effect of Ar on synthesizing Cu@C, especially on particle size. The minimum average size is around 13 nm, and most of the particle size distribution is in 5-10 nm range. When the argon concentration is high, the detonation process of H2 and O2 will be suppressed, which is not conducive to the graphitization. Conclusion: Argon gas has a catalytic effect on the synthesis of high-quality Cu@C, which could significantly reduce the particle size of detonation products; the grain size appears an obvious downtrend with the concentration of argon increasing, but the high concentration of Ar is disadvantageous for the graphitization of carbon shells.

Electrophoretically deposited nanostructured PdO thin film for room temperature amperometric H2 sensing

In the present work, economical and facile hydrothermal sol-gel method is employed for the synthesis of palladium oxide (PdO) nanoparticles. Uniform thin film of PdO nanoparticles are fabricated using Electrophoretic deposition (EPD) set-up. The crystal structure, surface framework, shape and size of PdO nanoparticles are determined using X-ray diffraction spectroscopy (XRD), Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) respectively. An optical band-gap of 1.9 eV is observed using UV-Visible (UV-Vis) spectroscopy. Amperometric sensing of hydrogen gas is studied using PdO thin film as working electrode and characteristics properties have been obtained for different hydrogen (H2)/Argon (Ar) gas concentrations using potentiostat/galvanostat Autolab instrument at room temperature. The PdO nanoparticles based amperometric hydrogen gas sensor shows high sensitivity of 0.222 μA/%H2 with fast response and recovery time.

A comparative study of Ti-6Al-4V powders for additive manufacturing by gas atomization, plasma rotating electrode process and plasma atomization

In this study, it is the first time to overall compare three types of spherical Ti-6Al-4V powders by gas atomization, plasma rotating electrode process and plasma atomization in terms of microstructure, porosity, argon gas content and pore spatial structure using scanning electron microscopy, mass spectrometer gas analyzer and synchrotron X-ray computed tomography (CT). It is found that the particle size plays a crucial role in the micro-morphology, porosity and argon gas content of the atomized powders. The experimental results show that the argon content of the gas atomized (GAed), plasma rotating electrode processed (PREPed) and plasma atomized (PAed) powders below 150 μm is 0.77 ± 0.06, 0.16 ± 0.06 and 0.70 ± 0.06 μg/g, while its porosity is 0.20 ± 0.01%, 0.08 ± 0.01% and 0.12 ± 0.01%, respectively. Both argon content and porosity within powders increase with increasing particle size for each type of powders. The results of three-dimensional reconstructed images from CT scanning present that the pore population, size and porosity within powders gradually increase with the increase of particle size. The pore sphericity of the GAed and PAed powders exhibits relatively higher than that of the PREPed powders due to different gas pressures inside of powders.

A pore morphological study of gas-atomized Ti-6Al-4V powders by scanning electron microscopy and synchrotron X-ray computed tomography

In this study, we fabricated spherical Ti-6Al-4V powders by gas atomization. High-resolutional synchrotron X-ray computed tomography (CT) and scanning electron microscopy were extensively performed to investigate the properties of the gas-atomized (GAed) Ti-6Al-4V powders. It is found that microstructure, porosity and argon gas content of the GAed powders are particle size dependent. The quantitative analysis shows that the porosity of powders rises from 0.05 ± 0.04% to 1.14 ± 0.11% when the particle size increases from 51.6 ± 3.9 to 224.2 ± 11.6 μm, respectively. Certain amount of the atomizing argon gas is detected in the GAed powders. The argon content in powders also increases with increasing particle size, consistent with the porosity analysis. The results of three-dimensional reconstruction by synchrotron X-ray CT show that the pore number, pore size and porosity in the GAed powders gradually decrease with decreasing particle size.

The effect of argon contamination on interfacial tension, diffusion coefficients and storage capacity in carbon sequestration processes

In this study, the effect of argon as a co-contaminant in a CO2 stream on interfacial tension, diffusion coefficients and storage capacity was experimentally determined under conditions relevant to carbon sequestration, using the pendant drop method. Interfacial properties affect primary capillary trapping mechanisms when CO2 is injected since they set a limit to storage capacity in a geological formation. A strong increase in the isothermal interfacial tension at 45 °C and up to 20 MPa was observed with an increase in Ar co-contamination from 5 vol.% up to 100 vol.%. Since Ar content is present in small concentrations in most injected CO2 streams, we focused on measuring brine-CO2 interfacial tension and brine mixture (CO2 and Ar) interfacial tension, with 5 vol.% and 10 vol.% of argon content at pressures from 7.5 MPa up to 40 MPa and in the temperature range from 40 °C to 80 °C, which has not previously been investigated and can be considered more oriented to real-world conditions for carbon sequestration. It was found that storage capacity decreased significantly from a scenario where pure CO2 was injected, down to a scenario where 5 vol.% and 10 vol.% Ar were co-injected into the CO2 stream. Additionally, the effect of other common impurities in CO2 streams on interfacial properties and storage capacity is discussed.In order to evaluate the risk of CO2 diffusion loss through a cap rock, we measured the diffusion coefficients of geological water in the injected fluid. It was found that the diffusion coefficients of water in Ar are higher in comparison to those of water in CO2. Small quantities of salt in water had a minor effect on the diffusion coefficients of brine in supercritical CO2. Experimentally obtained diffusion coefficients (Dab) were correlated to obtain the effective diffusion coefficient (Deff). It was found that, in the case of co-injection of Ar with CO2, the diffusive gas breakthrough could be enhanced.

Emission spectral diagnosis of argon-helium plasma produced by radio frequency capacitive discharge

Optically pumped metastable rare-gas laser (OPRGL) have been proposed to overcome the shortcomings of diode-pumped alkali-vapor laser in the recent years. The OPRGL promises to realize high-scale output. But how to achieve enough particle density of metastable atoms is still an open problem. Usually, plasma produced by discharge serves as a gain medium of the OPRGL. Here in this paper, we are to reveal the effects of different discharge parameters on the plasma properties, such as particle density of metastable argon atoms. Gas discharge at a radio frequency of 13.56 MHz is adopted to excite argon atoms. Emission spectrum is employed to study argon and helium radio frequency discharge of optically pumped argon laser at high pressure, different powers of discharge and various content of argon. Gas temperature is obtained by analyzing rotational spectrum (A2∑+ → X2Π) of OH radical generated by residual water vapor and comparing simulated spectrum with the measured spectrum. The electronic excitation temperature relating to electron temperature is obtained by the method of Boltzmann's plot. Stark broadening of the spectrum is used to determine the electron density. The results show that gas temperature rises slightly with the increase of pressure and varies little with content and discharge power changing. The electronic excitation temperature increases with the decrease of pressure evidently and decreases slightly with the increase of content. The electron density is on the order of 1015 cm-3 under various conditions controlled by us. Long time discharge test reveals that residual water vapor can lead to the decrease of electron temperature, and thus reducing the yield of argon metastable state. In conclusion, considering that the higher gas temperature can improve the collision relaxation rate of helium and argon, and the higher electron temperature can improve the rate of production of argon metastable state. Thus a proposal is put forward that appropriately heating gas and reducing gas pressure can obtain higher particle density of metastable argon. Furthermore, It can be found from these results that heating and cleaning the gas during discharge may be candidate methods to obtain and sustain the higher particle density in the plasma.

Graphene oxide reduction by solid-state laser irradiation for bolometric applications

We present a method for reduced graphene oxide (GO) patterning on the surface of GO film by a 445 nm solid-state laser with the adjustable fluence from 0.2–20 kJ cm−2. We demonstrate that the optimal argon concentration in air to obtain good quality reduced GO films is 90%. Varying the laser irradiation energy density allows controlling the resistance and IG/ID and IG/I2D ratios of Raman peak intensities. As a result, we demonstrate the possibility of forming of conductive patterns with a sheet resistance of 189 Ohm/□ and ∼1 μm film thickness by a local reduction of the GO. The fabricated structures reveal excellent bolometric response with a high speed and sensitivity to the radiation in the visible wavelength region.

Effects of Argon Concentration and Heat Treatment on the Mechanical Properties of Al65Cu20Fe15 Quasicrystal Alloy

Effects of Argon Concentration and Heat Treatment on the Mechanical Properties of Al65Cu20Fe15 Quasicrystal Alloy

Effect of Cryogenic Distillation and Chemical Absorption on the Argon Concentration in Krypton Purification

Cryogenic distillation and chemical absorption are two important means of inert gas purification. Experiments show that the order of the two methods has an effect on the final purification result. In order to verify the relationship between the retention of argon and the order of the two methods, experimental verification was designed. At the same time, the numerical simulation was carried out by using the principle of low temperature distillation, and the influence results of the two methods on the argon content after gas purification was obtained.

Experimental and modeling study on the role of Ar addition to the working gas on the development of intrinsic stress in TiN coatings produced by filtered vacuum-arc plasma

The aim of this work is to study and model the effect of argon addition to the N2 working gas on the intrinsic stress of TiN coatings deposited via rectilinear filtered vacuum arc plasma using substrate pulse bias potential. It was found that produced TiN coatings have a NaCl type cubic structure with the [110] axial texture regardless of the concentration of argon in the gas mixture. With increasing the content of argon in the gas mixture, the level of residual stress increased from 7GPa up to 10GPa and the coatings hardness remained at a high level of 27–32GPa. By mathematical modeling based on the modified Davis model, it was shown that increasing the stress level in the TiN coatings with increasing of argon content was due to the intensification of the bombardment process of the coating surface by the inert gas ions.

A Statistical Study About Photocatalytic Properties of Titania Crystals Deposited by Sputtering

Crystallized titania layers were prepared by vacuum sputtering in a DC magnetron. Photocatalytic properties of the crystals were analyzed using degradation of formaldehyde in a self-conception reactor. All data were analyzed using classical curve dependence and statistical. This study used Anova to find correlations between photocatalytic properties of the crystals and deposition parameters. The considered parameters were pressure, temperature of substrate, argon concentration and time of sputtering, all of this measured during the active process.

Experimental study on retardation of a heavy NAPL vapor in partially saturated porous media

Abstract. Non-aqueous-phase liquid (NAPL) contaminants introduced into the unsaturated zone spread as a liquid phase; however, they can also vaporize and migrate in a gaseous state. Vapor plumes migrate easily and thus pose a potential threat to underlying aquifers. Large-scale column experiments were performed to quantify partitioning processes responsible for the retardation of carbon disulfide (CS2) vapor in partially saturated porous media. The results were compared with a theoretical approach taking into account the partitioning into the aqueous phase as well as adsorption to the solid matrix and to the air–water interface. The experiments were conducted in large, vertical columns (i.d. of 0.109 m) of 2 m length packed with different porous media. A slug of CS2 vapor and the conservative tracer argon was injected at the bottom of the column followed by a nitrogen chase. Different seepage velocities were applied to characterize the transport and to evaluate their impact on retardation. Concentrations of CS2 and argon were measured at the top outlet of the column using two gas chromatographs. The temporal-moment analysis for step input was employed to evaluate concentration breakthrough curves and to quantify dispersion and retardation. The experiments conducted showed a pronounced retardation of CS2 in moist porous media which increased with water saturation. The comparison with an analytical solution helped to identify the relative contributions of partitioning processes to retardation. Thus, the experiments demonstrated that migrating CS2 vapor is retarded as a result of partitioning processes. Moreover, CS2 dissolved in the bulk water is amenable to biodegradation. The first evidence of CS2 decay by biodegradation was found in the experiments. The findings contribute to the understanding of vapor-plume transport in the unsaturated zone and provide valuable experimental data for the transfer to field-like conditions.

From micro to nanocrystalline boron doped diamond applied to cadmium detection

Cadmium detection was investigated by Square Wave Anodic Stripping Voltammetry (SWASV) measurements by using boron doped diamond electrodes with different morphologies from micro to nanocrocrystalline grains as Boron Doped Diamond (BDD) and Boron Doped Nanocrystalline Diamond (BDND), respectively. The argon concentrations, in the argon/hydrogen ratio, used were 0, 50, 60, 70, and 80vol.%. SWASV technique was applied in 4×10−4mol L−1 ammonium acetate buffer pH4.2. The peak currents were measured for Cd2+ concentration ranging from 1 to 20μgL−1. This change in film grain size and roughness affected how cadmium was deposited on the electrode surfaces, thus affecting its electroanalytical response from SWASV measurements as well as its selectivity. For all electrodes cadmium detection limits (DL) were lower than 1μgL−1 while for BDND electrode DL reached 0.016μgL−1. These values are lower than that required by the Brazilian Health Ministry for potable water (1μgL−1) and confirm that diamond electrodes are a suitable mercury-free method to determine cadmium trace levels in water. A strong correlation between the electrode selectivity and its grain size also confirmed the best performance of BDND electrode.

Evolution of plasma parameters in an Ar–N2/He inductive plasma source with magnetic pole enhancement

Magnetic pole enhanced inductively coupled plasmas (MaPE-ICPs) are a promising source for plasma-based etching and have a wide range of material processing applications. In the present study Langmuir probe and optical emission spectroscopy were used to monitor the evolution of plasma parameters in a MaPE-ICP Ar–N2/He mixture plasma. Electron density and temperature excitation temperature plasma potential skin depth and the evolution of the electron energy probability function (EEPF) are reported as a function of radiofrequency (RF) power, pressure and argon concentration in the mixture. It is observed that increases while decreases with increase in RF power and argon concentration in the mixture. The emission intensity of the argon line at 750.4 nm is also used to monitor the variation of the ‘high-energy tail’ of the EEPF with RF power and gas pressure. The EEPF has a ‘bi-Maxwellian’ distribution at low RF powers and higher pressure in a pure discharge. However, it evolves into a ‘Maxwellian’ distribution at RF powers greater than 70 W for pure and at 50 W for higher argon concentrations in the mixture. The effect of argon concentration on the temperatures of two electron groups in the ‘bi-Maxwellian’ EEPF is examined. The temperature of the low-energy electron group shows a decreasing trend with argon addition until the ‘thermalization’ of the two temperatures occurs, while the temperature of high-energy electrons decreases continuously.