Quartz Tube Research Articles

Measuring the thickness of thin sintered layers precisely

PhotonicsViewsVolume 20, Issue 2 p. 71-71 PreviewsFree Access Measuring the thickness of thin sintered layers precisely Considering the influence of sintering on optical constants, the thickness of sintered Al2O3 layers in quartz tubes can be accurately determined First published: 03 April 2023 https://doi.org/10.1002/phvs.202370217AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume20, Issue2April/May 2023Pages 71-71 RelatedInformation

Measuring the thickness of thin sintered layers precisely

AbstractOptical thickness determination with miniaturized spectrometers is a commonly used technique that works quite well in many applications. For sintered materials however, this technique must be extended by the determination of the optical constants of the sintered material. This can be done using a combination of scanning electron microscopy and effective medium approaches. In this article, we demonstrate this for the optical thickness determination of sintered Al2O3 layers in quartz tubes.

Fast gas quenching of microwave plasma effluent for enhanced CO2 conversion

Improvement of the CO2 conversion using a 2.45 GHz microwave plasma torch in reverse vortex configuration with cooled effluent channels at atmospheric pressure is reported. This configuration allows for fast gas quenching by efficient gas cooling of the effluent, which leads to conversion and energy efficiency results at 900 mbar that are very similar to the highest conversion and energy efficiency values typically obtained at lower pressures (100–200 mbar). The convective cooling in long cooled channels proved to be effective, particularly in the configuration with multiple channels, where the effective cooling surface was increased by a factor of 2.4. In comparison with the forward vortex the reverse configuration did not improve conversion, it did improve plasma stability, demonstrating that the observed effect can be attributed to the convective gas cooling in the effluent by gas-surface interaction. High specific energy inputs (> 5.5 eV/ molecule) were achieved in experiments where narrow gas inlets were used, resulting in 8 times higher inlet CO2 velocities that stabilised the plasma, allowing conversion values up to 57% at 900 mbar. The plasma stabilisation was most effective at low flow rates, where high gas velocity confined the plasma to the quartz tube centre and allowed coupling higher power to the plasma (high SEI). Additionally, experiments without a vacuum pump at atmospheric pressure were performed, yielding identical results as at 900 mbar, demonstrating that the vacuum pump is not needed to achieve high conversion rates with the use of the reverse vortex configuration with cooled effluent channels.

Effect of silicon carbide-based iron catalyst on reactor optimization for non-oxidative direct conversion of methane

The conversion of methane to olefins, aromatics, and hydrogen (MTOAH) can be used to stably obtain hydrocarbons when the effect of the catalytic surface is optimized from the reaction engineering perspective. In this study, Fe/SiC catalysts were packed into a quartz tube reactor. The catalytic surfaces of SiC and the impregnated Fe species decreased the apparent activation energies (Ea) of methane consumption in the blank reactor between 965 and 1020 °C. Consequently, the hydrocarbon yield increased by 2.4 times at 1020 °C. Based on the model reactions of ethane, ethylene, and acetylene mixed with hydrogen in the range of 500–1020 °C, an excess amount of Fe in the reactor favored the C–C coupling reaction over the selective hydrogenation of acetylene; consequently, coke formation was favored over the hydrogenation reaction. The gas-phase reactions and catalyst properties were optimized to increase hydrocarbon yields while reducing coke selectivity. The 0.2Fe catalyst-packed reactor (0.26 wt% Fe) resulted in a hydrocarbon yield of 7.1% and a coke selectivity of <2% when the ratio of the void space of the post-catalyst zone to the catalyst space was adjusted to be ≥2. Based on these findings, the facile approach of decoupling the reaction zone between the catalyst surface and the gas-phase reaction can provide insights into catalytic reactor design, thereby facilitating the scale-up from the laboratory to the commercial scale.

Synthesis, structural and spectroscopic investigations of dolomite-type MSn(BO3)2 with M = Mn, Fe, Co and Ni

Abstract Dolomite-type MSn(BO3)2 phases for M = Mn, Fe, Co and Ni have been synthesized using solid-state synthesis carried out in sealed quartz tubes. X-ray powder diffraction data Rietveld refinements confirm the rhombohedral space group R 3 ‾ $R\overline{3}$ for all compositions. The change in unit-cell parameters follows the increasing nature of the radius of the M-cations. Both the MO6 and SnO6 octahedra are found to be quite regular. 119Sn Mössbauer spectroscopy investigations complement the almost undistorted nature of the SnO6 octahedra and the tetra-valent charge of the tin-atoms. Detailed vibrational features are described from the Raman and the FTIR spectral data collected at ambient conditions. The frequency shifts of some selective Raman and IR bands are explained in terms of the change of cationic sizes and the respective M–O bond distances. The UV/Vis diffuse reflectance data are analyzed using the RATD method, leading to direct bandgaps for all the investigated samples. The wide bandgap semiconductors (3 – 4 eV) show increasing transition energies with increasing cation sizes of the high-spin M-cations in the dolomite types.

Nanostructured Polyaniline Films Functionalized through Auxiliary Nitrogen Addition in Atmospheric Pressure Plasma Polymerization

Polyaniline (PANI) was synthesized from liquid aniline, a nitrogen-containing aromatic compound, through the atmospheric pressure (AP) plasma process using a newly designed plasma jet array with wide spacing between plasma jets. To expand the area of the polymerized film, the newly proposed plasma jet array comprises three AP plasma jet devices spaced 7 mm apart in a triangular configuration and an electrodeless quartz tube capable of applying auxiliary gas in the center of the triangular plasma jets. The vaporized aniline monomer was synthesized into a PANI film using the proposed plasma array device. The effects of nitrogen gas addition on the morphological, chemical, and electrical properties of PANI films in AP argon plasma polymerization were examined. The iodine-doped PANI film was isolated from the atmosphere through encapsulation. The constant electrical resistance of the PANI film indicates that the conductive PANI film can achieve the desired resistance by controlling the atmospheric exposure time through encapsulation.

OZONE GENERATOR BASED ON SURFACE DIELECTRIC BARRIER DISCHARGE WITH PULSE POWER SUPPLY

A pilot model of an ozone generator with a pulsed power supply has been developed. The ozone generator can be used for disinfection of domestic and industrial premises, in medicine and the chemical industry. Ozone is generated by a surface dielectric barrier discharge reactor (SDBD), consisting of 18 parallel-connected quartz tubes, inside and outside of which spiral the stainless steel high-voltage electrodes are wound. The measurements of the main parameters of the ozone generator showed that the ozone concentration reached 57 mg/l, and the output ozone concentration is 9.4 g/h. The developed design takes into account the technical features of the implementation of a particular type of discharge used, allows reducing energy consumption for ozone generation, having improved output parameters.

Understanding the influence of additives on methyl orange degradation using adsorption/photocatalysis functioned materials

Dye wastewater has a severe influence on natural water environment. Using materials functioned by adsorption and/or photocatalysis to degrade dyes has received much attention due to high decolorization efficiency. However, there are a very limited knowledge on how co-existing additives influence dye degradation using the adsorption and/or photocatalysis materials. In this context, this study selected biochar-TiO2 composites to test whether different additives (anions, surfactants, thickeners and heavy metals) can affect the dye decolorization efficiency. The biochar-TiO2 composites, dye solution and selected additives were poured into a series of quartz tubes, which were put in a photochemical reactor equipped with a mercury lamp to simulate ultraviolet radiation. The outcomes showed that the biochar-TiO2 composites had a strong capacity of degrading eight dyes with different characteristics and structures. After 1-hour dark adsorption, the decolorization efficiency of the eight dyes were 40 %–99.89 % while after 1-hour photocatalytic reaction, the decolorization efficiency all reached nearly 100 %. In addition, taking methyl orange (MO) as a case study, it is found that the presence of different additive types had different influences on MO degradation via positively/negatively affecting dark adsorption and/or photocatalytic reaction. The influence mechanisms of different additives were also explored such as occupying adsorption sites (negative influence) and stimulating the creation of ·OH (positive influence). The research outcomes are expected to contribute the useful knowledge to effective dye wastewater treatment.

Selective supply of atomic oxygen to a surface placed in room air using vacuum ultraviolet photolysis of carbon dioxide

Reactive species play important roles in plasma treatments of surfaces, including polymers, metals, water, and living tissues. To elucidate the surface reaction mechanism, it is crucial to measure the effect of each type of reactive species on the surface treatment. Accordingly, we previously developed a method to selectively supply OH or O radicals to a surface placed in room air. Ar/H2O or Ar/O2 gas flowing through a quartz tube is irradiated with a vacuum ultraviolet lamp, causing photodissociation of H2O and O2 to produce OH and O. The resulting gas flows to the surface from the tube end. The O density supplied to the surface, however, is only approximately cm−3 according to our simulation, which is not sufficient to determine the surface treatment effect of O atoms. Therefore, in this study, a new method is proposed, supplying O atoms with a density that is two orders of magnitude higher. Specifically, CO2 gas is used as the medium to be photodissociated instead of O2 gas. The performance of this method is discussed herein using simulation results. The maximum O density supplied to the surface reaches cm−3 according to the simulation. Additionally, the experimental results demonstrate that the newly developed method can supply a sufficient amount of O atoms to selectively measure the effect of O atoms on the surface treatment of polypropylene (PP). In particular, the water contact angle (WCA) is considered as an index of the surface treatment. As a result, O atoms decrease the WCA of the PP surface at rates of the same order of magnitude as OH.

Performance modeling of quartz tube for gravity-driven solid particle solar receiver

The interest in high-temperature solar receivers is increasing due to more and more applications in industrial fields. The solid particle is a promising heat transfer fluid for high-temperature receivers owing to the advantages of direct absorption, low cost, and high allowable temperature (∼1300 °C). The re-radiation losses of solid particles inevitably increase with the higher operating temperature. The quartz tube with a spectral selective transmissivity may be used for reducing re-radiation losses. This paper proposed a mathematical model to describe the heat transfer behaviors of the gravity-driven solid particle solar receiver with a quartz tube covered. The wavelength-dependent radiative properties of the quartz tube and particles were approximated by a gray band method. On-sun tests based on a linear-focused solar furnace were conducted, and test results verified the proposed model. Analysis results show that a reduction in β from 3676m−1 to 1000m−1 can boost the volume absorption effect and increase the solar-to-thermal efficiency from 0.54 to 0.64. A double-layered quartz tube design provides the best thermal performance by increasing the greenhouse effect of the quartz tube from −0.02∼0.08 to 0.41. The analysis results could be used for the optimal design and operation of the gravity-driven solid particle solar receiver.

Catalytic methane pyrolysis for simultaneous production of hydrogen and graphitic carbon using a ceramic sparger in a molten NiSn alloy

Catalytic methane pyrolysis (CMP) for simultaneous hydrogen and carbon production has been achieved in molten NiSn liquid alloys, with the additional benefit of spontaneous separation of solid carbon from the liquid catalyst. Here, the use of ceramic spargers for the injection of CH4 bubbles into the molten liquid has shown to be advantageous not only in enhancing the CH4 conversion above 90%, but also in producing graphitic carbon. When a quartz tube was used to feed CH4 bubbles into the molten alloy, the conversation was limited to about 15–25% and the quality of the graphitic carbon product was more defective and disordered. Regardless of the use of the spargers, carbon precipitates preferentially accumulate at the top of the molten alloy, and steady-state conversion over 24 h with high selectivity towards H2 was achieved under a constant flow rate of pure CH4 without any pressure increase. The synergistic effect of the ceramic sparger on molten NiSn may be the result of a controlled bubble size of CH4 and a catalytic role of zirconia surfaces in contact with the molten alloy. Our results imply that there is a great opportunity to improve CMP in molten alloy catalysts further toward a scalable production of H2 and graphitic carbon with a nearly complete conversion of CH4.

Development of a Sensitive Method for Cadmium Determination in Fish Tissue and Drinking Water Samples by FAAS Using SQT In Situ Atom Trapping.

A sensitive and robust trap method was developed for the determination of cadmium (Cd) by using a slotted quartz tube. Using this method at a sample suction rate of 7.4 mL/min for 4.0 min collection, a 1467-fold increase in sensitivity was obtained compared to the flame atomic absorption spectrometry method. Under the optimized conditions, a limit of detection of 0.075 ng mL-1 was obtained for the trap method. The interference effects of hydride-forming elements, transition metals, and some anions on the Cd signal were investigated. The developed method was evaluated by analyzing "Sewage Sludge-industrial origin (BCR no: 146R)", "NIST SRM 1640a Trace elements in natural water", and "DOLT: 5 Dogfish Liver". There was a good agreement between the certified and found values at the 95% confidence level. This method was applied successfully for the determination of Cd in drinking water and some fish tissue samples (liver, muscle, and gill) obtained from Muğla province.

A novel photochemical conversion technique for reliable calibration of peroxyacetyl nitrate (PAN) analyzers

Photochemical synthesis of peroxyacetyl nitrate (PAN) through irradiating air mixtures of NO and acetone is prevailingly adopted for calibrating PAN analyzers, but few users of PAN analyzers provide evidence to certify the calibration reliability. Here we report a nonnegligible variation (up to ~50 %) of PAN synthesized in the calibration unit of a commercial PAN analyzer, whereas PAN synthesized in the two custom-made reactors could achieve stable values with variations of <2.5 %. Compared with a straight quartz tube flow reactor (SQTFR), PAN synthesized by a coiled quartz tube flow reactor (CQTFR) could achieve more stable (relative standard deviation: <0.66 % versus 2.49 %) and larger (PANCQTFR/PANSQTFR: 1.04–1.10) values. The residence time and reaction temperature of photochemical mixtures in CQTFR were found to be the key factors affecting PAN synthesis, with their optimal values of 30–60 s and 30–35 °C for achieving the highest PAN levels. The photochemical conversion efficiencies of NO to PAN in CQTFR under the optimal conditions were successfully measured to be 98.5 ± 0.5 % based on the alkaline-absorption method. Therefore, CQTFR is suggested to be adopted for calibrating PAN analyzers to reduce calibration uncertainties.

Contrasting the characteristics of atmospheric pressure plasma jets operated with single and double dielectric material: physicochemical characteristics and application to bacterial killing

This study reports an experimental comparison of two types of atmospheric pressure plasma jets in terms of their fundamental plasma characteristics and efficacy in bacterial sterilization. The plasma jets are fabricated by inserting a high voltage electrode inside a one-end closed (double DBD plasma jet) or both ends open (single DBD plasma jet) quartz tubes which are further enclosed inside a second quartz tube containing a ground electrode. Both plasma jets are operated in contact with water surface by using a unipolar pulsed DC power supply with helium as the working gas. Results from electrical and time-resolved imaging show that the single DBD configuration induces 3–4 times higher accumulation of charges onto the water surface with significantly faster propagation of plasma bullets. These results are accompanied by the higher discharge intensity as well as stronger emissions from short-lived reactive species which were analyzed through optical emission spectroscopy at the plasma-water interface. The rotational temperature for the single DBD configuration was observed to be higher making it unsafe for direct treatments of sensitive biological targets. These characteristics of the single DBD configuration result in the production of more than two times higher concentration of H2O2 in plasma activated water. Shielding of the HV electrode reduces the plasma potential which in turn reduces the electric field & electron energy at the plasma-water interface. The reduced electric field for the double DBD configuration was lower by ≈463 Td than the single DBD configuration. The bactericidal efficacy of the two configurations of the plasma jets were tested against Escherichia coli, a well studied Gram-negative bacterium that can be commensal and pathogenic in human body. Our results demonstrate that although single DBD plasma jet result in stronger antibacterial effects, the double DBD configuration could be safer.

Investigating the Effect of Ni Loading on the Performance of Yttria-Stabilised Zirconia Supported Ni Catalyst during CO2 Methanation

CO2 methanation was studied on Ni-based yttria-stabilised zirconia (Ni/YSZ) catalysts. The catalysts were prepared by the wet impregnation method, where the amount of Ni content was varied from 5% to 75%. Thereafter, the prepared catalysts were analysed by BET, XRD, SEM and H2-TPR. BET results showed an initial increase in the surface area with an increase in Ni loading, then a decrease after 30% Ni loading. The XRD results revealed that the Ni crystallite size increased as the Ni loading increased, while the H2-TPR showed a shift in reduction peak temperature to a higher temperature, indicating that the reducibility of the catalysts decreased as the Ni loading increased. The activity of the synthesised catalysts for CO2 methanation was studied by passing a mixture of H2, CO2 and N2 with a total flow of 135 mL min−1 and GHSV of 40,500 mL h−1 g−1 through a continuous flow quartz tube fixed-bed reactor (I.D. = 5.5 mm, wall thickness = 2 mm) containing 200 mg of the catalyst at a temperature range of 473 to 703 K under atmospheric pressure and a H2:CO2 ratio of 4. The tested Ni/YSZ catalysts showed an improvement in activity as the reaction temperature increased from 473 K to around 613 to 653 K, depending on the Ni loading. Beyond the optimum temperature, the catalyst’s activity started to decline, irrespective of the Ni loading. In particular, the 40% Ni/YSZ catalyst displayed the best performance, followed by the 30% Ni/YSZ catalyst. The improved activity at high Ni loading (40% Ni) was attributed to the increase in hydrogen coverage and improved site for both H2 and CO2 adsorption and activation.

Mathematical Modeling of Capillary Drawing Stability for Hollow Optical Fibers

The stability problem solution of the manufacturing (drawing) of the quartz capillaries (pipes) for microstructured optical fibers (hole-assisted fiber) is important for determining the effective technological production modes. This importance is also caused by the high cost of fiber production and strict requirements for the accuracy of the fiber’s geometric characteristics. Therefore, a theoretical approach to this problem is relevant and necessary. A modified capillary drawing model that takes into account inertial, viscous, and surface tension forces, as well as all types of heat transfer is proposed in the research. Within the framework of the linear theory of stability, a mathematical model of isothermal and nonisothermal capillary drawing has been developed. The stability of the process is studied depending on the drawing ratio and the Reynolds number. The analysis of the sensitivity of the process to perturbations in the boundary conditions is carried out. The secondary flow that occurs upon transition to the region of instability is also studied. It has been found that at draw ratios above critical values (instability region), undamped oscillations arise. The existence of optimal parameters of the heating element is shown: temperature distribution over the furnace surface and furnace radius, at which the stability of the process of drawing quartz tubes increases significantly (several times).

Effects of gas inlet orientation on discharge characteristics of coaxial dual-channel cross-field atmospheric plasma jet

In this paper, the effect of the gas inlet orientation on the discharge characteristics of the coaxial dual-channel cross-field plasma jet is investigated. A working gas helium is separately flowed into the annular space between the hollow needle tube and the quartz tube (called Q-Jet), as well as the hollow needle tube (called N-Jet). With the same discharge parameters, the results show that the radial and axial dimensions of Q-Jet plasma jet are larger than that of N-Jet. Compared with the latter, the discharge current amplitude of the former increases by about 3.8-fold, the net charge transferred increases by about 8.8-fold, and the variety and density of reactive species produced are remarkably increased. For Q-Jet, the 706-nm spectral band is distributed inside and outside the quartz tube, while the 391-nm spectral band is mainly distributed outside the quartz tube, and the plasma jet forms a conical luminous pattern in the quartz tube during the positive half cycle of the voltage, due to the influence of helium viscosity. For N-Jet, 706- and 391-nm spectral bands are only just distributed in the axis of the quartz tube, and the charges left by the first discharge in the axial position of the quartz tube remarkably amplify the intensity of the second discharge in the positive half cycle.

The influence of electrodes thicknesses on the characteristics of a helium plasma jet

An atmospheric plasma jet reactor (PJR) was designed using two outer disc-like copper plats placed around a quartz tube. The effects of the electrodes’ thicknesses and their placement on the plasma jet length created in helium and its electrical characteristics were investigated. Measurements of the plasma jet length were carried out for different applied voltages and different gas flow rates. The electrical characteristics (such as discharge current and power consumption) of the plasma jet obtained using a high voltage generator delivering a sin-wave signal varying from 13kVp-p to 17kVp-p at a resonance frequency of 5.5kHz, were measured/calculated. The best results (long plasma plume and intense plasma) were obtained with a reactor equipped with a thicker upper electrode and a thinner lower electrode. Using this configuration, a plasma plume 55mm long was reached at 17kVp-p and 7slm of helium.

Emission characteristic of OVOCs, I/SVOCs, OC and EC from wood combustion at different moisture contents

Wood combustion is an important source of organic compounds, and its emission characteristics are affected by many factors, among which fuel moisture content (MC) is poorly understood. In this study, wood with MC of 2.5%, 10.9%, 19.2%, 31.4%, and 43.2% were prepared by stepwise dehydration of fresh pine, and burned separately in a quartz tube furnace at different ignition temperatures (400, 600, and 800 °C), in order to discuss the effects of MC on the emission characteristics of gas- and particle-phase organic compounds. The results showed that the effects of MC on the emission factors (EFs) of organic compounds were significant. When MC was close to 10%, the average EFs of carbonyl compounds (CCs), intermediate volatile organic compounds (IVOCs), polycyclic aromatic hydrocarbons (PAHs), n-alkanes, organic carbon (OC), and elemental carbon (EC) were 832.0 ± 518.5, 439.3 ± 111.6, 44.3 ± 6.6, 59.3 ± 9.3 mg/kg, and 2.4 ± 0.2, 0.8 ± 0.8 g/kg, respectively whereas when MC was near 30%, all the EFs reached the maximum and were 2.4, 3.1, 2.6, 4.2, and 3.1 times the lowest values, respectively. The MC and ignition temperature together affected the composition of organic compounds, with different organic profiles observed at various MCs when the temperature increased from 400 to 800 °C. For example, at MC ≈ 10%, the proportion of unresolved complex mixture (UCM) in IVOCs decreased from 59.7% to 43.4%, while the proportion of 5-6-ring PAHs increased from 7.4% to 35.4%. However, at MC ≈ 30%, formaldehyde and acetaldehyde in CCs decreased from >60% to ∼40%. In brief, the influence of MC may explain to a large extent the differences in organic emission characteristics of wood burned in the stove and open burning, and MC should be further considered in the experiments on the measurement of organic compound emissions from biomass burning.

Assessment of back-side activation of titania thin film using a fixed-bed photocatalytic-reactor: Kinetic study, operating cost and ANN modeling

This work is concerned with construction, application and modeling of a thin-film fixed photocatalytic bed multi lamp photo-reactor as an organic pollutant treatment system. Five photocatalytic units were located in a cylindrical vessel with a recycling current. In each unit, a thin layer of titania nanoparticles was coated on the outer surface of a quartz tube which a UV lamp was installed inside it. By this configuration, the UV lamps irradiation can approach directly to the photocatalyst particles before penetration into the reaction media. The effect of initial pH, initial DR16 (as model pollutant) dosage, H2O2 (as auxiliary oxidant) concentration and number of applied activated photocatalytic units were studied. The process was monitored via the kinetic rate constant and operating cost factors. The photocatalytic degradation of DR16 molecules in the constructed multi lamp photo-reactor followed a pseudo-first-order kinetic, and well described by the Langmuir-Hinshelwood equation. Under the initial pH of 3, 150 mg/L of H2O2 and illumination of the five lamps, complete degradation of the target pollutant was achieved after 60 min. Under these conditions, the rate constant and operating cost were 0.078 min−1 and 1.13 US$/m3 respectively. The real photon flux inside the reactor and quantum efficiency of the photocatalytic degradation of DR16, using five turned on lamps, were evaluated as 10.84 × 10−6 (einstein.s−1) and 0.009 respectively Also, the photocatalytic process was well modeled (with mean square error of 16.81 ×10−5) by a three layered feed forward back propagation artificial neural network consists of trainlm as training function, 7 hidden neurons and tansig-tansig as transfer functions calibrated at 156th epoch.