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1
Suprihanto, Agus. "HIGH TEMPERATURE GAS NITRIDING TREATMENT OF AISI 430 USING LOW AND HIGH PURITY NITROGEN GAS." ROTASI 18, no. 3 (July 1, 2016): 65. http://dx.doi.org/10.14710/rotasi.18.3.65-68.
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The properties of stainless steels can be improved by high temperature gas nitriding (HTGN) treatment. The improving of their properties are obtained from nitrogen atom which diffuse into stainless steel. Nitrogen gas is the main source of nitrogen atom on the HTGN treatment. Generally, these treatment use high purity of nitrogen gas. The aim of this research is to investigate the effect of nitrogen gas purity on the HTGN treatment for AISI 430. Stainless steel AISI 430 plate 2 mm thick was processed by HTGN treatment. The specimens was exposed at nitrogen gas atmosphere at temperature 1200oC and held for 2 hours prior quenching in water. The treatment used industrial/welding grade (99.5%) as low nitrogen gas purity and ultra high purity (UHP) grade (99.999%) as high nitrogen gas purity. The vickers micro-hardness test was conducted to evaluate the hardness distribution from surface into middle section of the specimens before and after treatment. Light optical microscope was applied to examine the microstructure of specimens after treatment. Metallographic examination shows both treatments using low and high purity gas have the same grain size. However HTGN treatment using low purity of nitrogen gas produces hardness slightly lower than the high purity. This is due the high content of impurity of the low purity gas that reduces the partial pressure of nitrogen gas. Another effect of impurity is the reaction between nitrogen gas and its impurity especially oxygen gas. These reactions reduce the amount of free nitrogen atom which diffuses on the stainless steel.
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Warnatz, Jürgen. "Hydrocarbon oxidation high-temperature chemistry." Pure and Applied Chemistry 72, no. 11 (January 1, 2000): 2101–10. http://dx.doi.org/10.1351/pac200072112101.
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The exact knowledge of hydrocarbon oxidation kinetics is very important due to the fact that this process is involved in many technological processes: combustion in engines and furnaces, flame synthesis of materials, partial oxidation processes in chemical technology, catalytic combustion, and exhaust gas treatment, etc. An overview is given on the present state of the art with respect to kinetic data on gas-phase and (shortly) surface oxidation of hydrocarbons. Furthermore, some applications are described in the areas mentioned above. Examples for the importance of the gas-phase oxidation of hydrocarbons are ignition and combustion in engines and furnaces and partial oxidation processes in industrial chemical reactors. In many applications, both gas-phase and surface chemistry are taking place. Examples here are flame generation of diamonds and syngas generation.
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Ma, Jian, Yunlong Zhang, Jiakun Lv, and Kun Yu. "Experimental Study on Permeability Characteristics of Mudstone under High Temperature Overburden Condition." Processes 11, no. 10 (September 25, 2023): 2828. http://dx.doi.org/10.3390/pr11102828.
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High-temperature treatment significantly impacts the permeability of mudstone. The permeability of mudstone after exposure to high temperatures is closely influenced by the temperature it experiences and the stress state it is subjected to. This study examines the change in macroscopic physico-mechanical properties of mudstone with temperature following high-temperature treatment. Additionally, we conducted experimental research on the gas and water seepage behavior of mudstone specimens from the top of the coal seam of Taiyuan Group–Shanxi Group in the Ordos Basin. The coal-rock mechanics-permeability test system TAWD-2000 was employed for this purpose. Subsequently, we analyzed the evolution of mudstone permeability after high-temperature treatment with consideration to temperature, axial pressure, and other influencing factors. The findings reveal that gas permeability of mudstone gradually increases with increasing temperature, while water permeability initially decreases and subsequently increases. Furthermore, both gas and water permeability of mudstone exhibit a trend of decreasing and then increasing with rising stress levels after undergoing the same high-temperature treatment. We constructed a quadratic mathematical model with a goodness of fit of 99.4% and 89.2% to describe the relationship between temperature–stress coupling and mudstone gas and water permeability. This model underscores the significance of temperature–stress coupling on mudstone permeability and provides valuable guidance for numerically calculating the gas–water transport law of peripheral rock in the underground coal gasification process and its practical application in engineering.
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Chng, Elaine Lay Khim, Hwee Ling Poh, Zdeněk Sofer, and Martin Pumera. "Purification of carbon nanotubes by high temperature chlorine gas treatment." Physical Chemistry Chemical Physics 15, no. 15 (2013): 5615. http://dx.doi.org/10.1039/c3cp50348h.
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Wang, Sheng, Tao Wang, Yuanwei Ding, Youfeng Xu, Qiying Su, Yanlong Gao, Guohua Jiang, and Wenxing Chen. "Gas-Supported High-Photoactivity TiO2Nanotubes." Journal of Nanomaterials 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/909473.
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By changing hydrothermal condition and post-heat-treatment temperature, silica-coatedTiO2nanotubes are obtained successfully. The effects of gas-supported process on tubular morphology, crystallinity, and photocatalytic activity are discussed. It is found that the sample prepared at hydrothermal treatment (180°C/9 h) and calcination (650°C/2 h) shows perfect open-ended tubular morphology and increased crystallinity. The photoactivity of the sample is proved to be 5 times higher than that ofTiO2nanoparticles.
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Liu, Jun Li, Jian Chun Jiang, and Wei Hong Yang. "Preparation of High Heating Value Gas, High Quality Bio-Oil and Added Value Carbon Materials from Caragana Pyrolyzed via Super-High Temperature Steam." Advanced Materials Research 512-515 (May 2012): 2152–61. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.2152.
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Caragana is an abundant plant as the feedstock of biomass energy in China. In this study, pyrolysis of Caragana in the presence of high temperature medium and characterization of products has been carried out. Evaluation of experimental results showed that faster devolatilization and char with increased surface area obtained in the presence of high temperature steam comparing to N2. Analysis of the obtained liquid revealed that the H/C and O/C ratios in the liquid are 1.5 and 0.16 respectively. Further more gas composition during high temperature steam pyrolysis differs from gas composition derived from N2pyrolysis which indicates interaction of steam with vapors and solid species even at low treatment temperatures. The derived products’ yields and characteristics indicate possible exploitation of derived char as activate carbon precursor. Liquid fraction composition makes it suitable for exploitation as liquid fuel and/or chemical feedstock.
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Hwa, Mei Yin, Ching Hsing Lin, Yu Jie Chang, Yao Chuan Lee, I. Ray Liu, and Jen Ray Chang. "Pt/Zeolite Catalyst for the Treatment of High VOC-Containing Wastewater." Advanced Materials Research 123-125 (August 2010): 927–30. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.927.
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Pd/SDB (Styrene Divinylbenzene Copolymer), a hydrophobic catalyst, has been used for the destruction of volatile organic compounds (VOCs) in wastewater. Although the catalysts performed well in low VOC concentrations, they were not as effective in high VOC concentrations because of the heat removal problem. On the other hand, Pt/Zeolite contains a high silica to alumina ratio, which gives it hydrophobic characteristics and allows it to endure significantly higher temperatures than Pd/SDB. Hence, they were chosen for the treatment of wastewater containing high VOC concentrations. As expected, the catalysts presented both high conversion rates and good stability maintenance. Because of their high stability and rapid regeneration, the catalysts were regarded to be promising for industrial applications. In this study, the noble metal content of Pt/Zeolite amounted to 1.5 wt.%, and that the different temperatures and pressures collocating with different weight hourly space velocity (WHSV) were used to test the VOCs conversion efficiency. The results showed that the best reduction temperature was 450°C below the temperature- programmed reduction (TPR) process. The reaction system consisted of a continuous dripping flow with a fix-bed system and proportional integral derivative (PID) temperature controller. Selected VOCs such as methanol, ethanol, propanol and formaldehyde were investigated over the catalyst. Qualitative and quantitative analysis of the reagents and the potential organic intermediates was determined using gas chromatography with a flame ionization detector (FID). The experimental results indicated that the reaction rate is inversely proportional to the molecular weight for the compounds with the same functional group. For the same molecular weight, aldehyde is easier to destroy than alcohol. Ethanol and propanol, atypical products of incomplete oxidation of alcohols, were detected in the reaction gas. To minimize the energy consumption, we preferred liquid phase reaction since the heat of reaction could maintain the reaction temperature.
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Suprihanto, Agus. "Magnetic Properties of Austenitic Stainless Steel 316l and 316lvm after High Temperature Gas Nitriding Treatment." ROTASI 19, no. 2 (July 20, 2017): 72. http://dx.doi.org/10.14710/rotasi.19.2.72-75.
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Biometallic materials for implant devices not only have to good corrosion resistance but also stable nonmagnetic properties. Various method have been developed for enhanced the corrosion resistance i.e low temperature gas nitriding treatments. Unfortunatelly, low temperature gas nitriding produce weakly ferromagnetic due the presence of expanded austenitic phases. Another treatments methods which is capable for improvement the mechanical properties is high temperature gas nitriding. However, the evaluation of magnetic properties of austenitic stainless steel 316L and 316LVM not yet investigation. The evaluation of magnetic properties of austenitis stainless steel 316L and 316LVM after high temperature gas nitriding treatments have been succesfully done. The magnetic properties are evaluated by vibrating sample magnetometre (VSM) test. The magnetic properties such as magnetic remenance, magnetic saturation and magnetic permeability are improved. As treated 316L and 316LVM have more stable non-magnetic properties and they more safe and compatible for MRI test
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Kim, Hyung Ick, Hong Sun Park, Bong Kook Bae, Young Min Lee, Chang Sung Seok, and Moon Young Kim. "Evaluation of High Temperature Characteristics in Gas Turbine Blades." Key Engineering Materials 321-323 (October 2006): 632–35. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.632.
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The Ni-based superalloy GTD-111DS has been widely used as the material of the first stage blade of gas turbine. But there are little data available on the microstructure and mechanical property. The strength and ductility of GTD-111DS decrease more rapidly due to the acceleration of its microstructure degradation under high temperature. The results of study showed that the shape of γ' did not change with increased aging time but the amount and volume fraction of the deposition of secondary γ' increased and secondary γ' grew among primary γ'. Also there was difference of yield strength and tensile strength in room temperature according to heat treatment and collecting region.
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Abeysinghe, Subhashini K., Dennis H. Greer, and Suzy Y. Rogiers. "Interaction effects of temperature and light on shoot architecture, growth dynamics and gas exchange of young Vitis vinifera cv. Shiraz vines in controlled environment conditions." Functional Plant Biology 49, no. 1 (2022): 54. http://dx.doi.org/10.1071/fp21271.
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To examine the interactive effect of temperature and photon flux density (PFD) on growth dynamics and gas exchange of young Vitis vinifera L. cv. Shiraz vines, a controlled environment study was conducted by exposing vines to two different temperatures combined with either high or low PFD. Shoot growth was accelerated and the phyllochron of Shiraz leaves was hastened in the low temperature (25/12°C)×low PFD condition (350μmolm−2s−1). In early emerging leaves, leaf area was responsive to temperature whereas in later emerging leaves it was dependent on light intensity. The high temperature (32/20°C)×high PFD (700μmolm−2s−1) treatment delayed internode extension of early emerging internodes. However, low temperature×high PFD increased leaf gas exchange across the different growth stages. The net shoot carbon balance was greater for the low temperature×high PFD treatment. Dry matter accumulation was also greater in early emerging internodes irrespective of treatment. These results on young Shiraz vines indicate that 25°C is favourable to 32°C, and some growth characteristics are accelerated at low PFD while others favour higher PFD.
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Desforges, Alexandre, Guillaume Mercier, Claire Hérold, Jérôme Gleize, François Le Normand, and Brigitte Vigolo. "Improvement of carbon nanotube stability by high temperature oxygen/chlorine gas treatment." Carbon 76 (September 2014): 275–84. http://dx.doi.org/10.1016/j.carbon.2014.04.078.
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Cherednichenko, P. I., and V. A. Kosenok. "Gas seal for installations for high-temperature treatment of carbon fibre materials." Fibre Chemistry 26, no. 3 (1994): 205–6. http://dx.doi.org/10.1007/bf00545637.
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Wu, Jinquan. "Experimental Study on Gas Permeability Semiempirical Model of Granite after Heat Treatment." Advances in Civil Engineering 2022 (September 6, 2022): 1–7. http://dx.doi.org/10.1155/2022/2812413.
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High temperature will cause a thermal crack of a rock, thus affecting the permeability change of rock. To explore the effects of temperature on permeability and microstructure of rock microstructure, the granite after 50–800 C thermal treatment was carried out by gas permeability test, combined with computed tomography (CT) scanning technology. The granite internal three-dimensional reconstruction was conducted after high-temperature thermal treatment, and the characteristics of the microstructure were also deeply analyzed. On this basis, the applicability of the Costa model under high temperature was discussed. Finally, the temperature-permeability model of granite after the high temperature was proposed combined with the pore fractal model. The new model was verified with experimental data.
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Orikawa, M., H. Kamahara, Y. Atsuta, and H. Daimon. "Application of Hydrothermal Treatment to High Concentrated Sewage Sludge for Anaerobic Digestion Process." International Journal of Renewable Energy Development 2, no. 3 (October 30, 2013): 165–68. http://dx.doi.org/10.14710/ijred.2.3.165-168.
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Tomato and seaweed were produced by utilizing CO2 and heat discharged from power generation using biogas in Toyogawa biomass park, Japan. The biogas was obtained by anaerobic digestion with hydrothermal treatment. The hydrothermal treatment was applied to the high concentrated sewage sludge (22 % total solids (TS) dewatered sludge). The purpose of this study is to clarify the effect of hydrothermal treatment on the qualities of high concentrated sewage sludge, by analyzing particulate organic carbon (POC) and dissolved organic carbon (DOC). The hydrothermal treatment was investigated under 10-60 min of treatment time, 180-200 °C of temperature, 10-22 %-TS of sewage sludge concentration. The results showed that the DOC in each conditions increased through hydrothermal treatment. The highest DOC obtained was 67 % of total carbon concentration, when the temperature was 180 °C, treatment time was 60 min and sewage sludge concentration was 10 %-TS. Furthermore, the viscosity of treated sewage sludge was decreased by hydrothermal treatment. In batch anaerobic digestion test, methane gas production was confirmed. In addition, this study evaluated the energy balance of this system. Thus, the results of this study indicated that the possibility of application of hydrothermal treatment to high concentrated sewage sludge for anaerobic digestion process. Keywords: anaerobic reaction, hydrothermal treatment, sewage sludge, solubilization
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Eustis, Ashley, Kevin M. Murphy, and Felipe H. Barrios-Masias. "Leaf Gas Exchange Performance of Ten Quinoa Genotypes under a Simulated Heat Wave." Plants 9, no. 1 (January 9, 2020): 81. http://dx.doi.org/10.3390/plants9010081.
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Quinoa (Chenopodium quinoa Willd.) is a highly nutritious crop that is resilient to a wide range of abiotic stresses; however, sensitivity to high temperatures is regarded as an impediment to adoption in regions prone to heat waves. Heat stress is usually associated with a decrease in crop reproductive capacity (e.g., pollen viability), yet little is known about how leaf physiological performance of quinoa is affected by high temperatures. Several trials were conducted to understand the effect of high temperatures, without confounding stressors such as drought, on ten selected quinoa genotypes considered to encompass heat sensitive and heat tolerant plant material. Plants were grown under favorable temperatures and exposed to two temperature treatments over four consecutive days. The heat treatment simulated heat waves with maximum and minimum temperatures higher during the day and night, while the control treatment was maintained under favorable temperatures (maximum and minimum temperatures for ‘Heat’: 45/30 °C and ‘Control’: 20/14 °C). Leaf gas exchange (day), chlorophyll fluorescence (predawn and day) and dark respiration (night) were measured. Results show that most quinoa genotypes under the heat treatment increased their photosynthetic rates and stomatal conductance, resulting in a lower intrinsic water use efficiency. This was partly corroborated by an increase in the maximum quantum yield of photosystem II (Fv/Fm). Dark respiration decreased under the heat treatment in most genotypes, and temperature treatment did not affect aboveground biomass by harvest (shoot and seeds). These results suggest that heat stress alone favors increases in leaf carbon assimilation capacity although the tradeoff is higher plant water demand, which may lead to plant water stress and lower yields under non-irrigated field conditions.
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Kuznetsov, M. P. "Modeling of a low-temperature gas treatment system." Herald of Dagestan State Technical University. Technical Sciences 50, no. 3 (October 27, 2023): 14–23. http://dx.doi.org/10.21822/2073-6185-2023-50-3-14-23.
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Objective. The main purpose of the work is: investigation of the effect of changes in technological parameters on the efficiency of the separation process and determination of optimal technological modes of operation of gas field X CNTS in the separation process.Method. The problem was solved in the KBC Petro-SIM computer program and the LTS model was built. To conduct the study, a model of the LTS was built in the KBC Petro-SIM computer program.Result. The results obtained with the help of it showed: with the current composition of the gas with a decrease in temperature for every 2oC, with other technological indicators being equal, the specific condensate yield increases in the range from 15 to 30%, and the lower the temperature, the higher this percentage. When the pressure on the throttle decreases by every 0.4 MPa, the condensate output increases, if the pressure drops below 1.8 MPa, the specific condensate output will begin to decrease, which is explained by the pressure drop below the maximum condensation line of the phase diagram. The change in gas flow within the design values did not affect the operation of low-temperature separation. At any available low temperature and high pressure at the inlet to the ILTS, the most optimal mode will be when the pressure after the throttle is maintained within 1.8 - 1.9 MPa. The maximum specific yield of gas condensate (48.21%) was obtained at a pressure at the inlet to the ILTS of 5.1 MPa, a temperature after the heat exchanger of minus 2oC and a pressure drop at the throttle of 3.05 MPa. As part of the numerical research, the following results were obtained: with an increase in the pressure at the inlet to the ILTC, the change in the specific output of the gas condensate is insignificant, but with this parameter it is possible to create a larger pressure drop on the throttle; with a decrease in the gas temperature at the outlet of the heat exchanger, the specific yield of the gas condensate will increase; with an increase in the pressure drop at the throttle, the specific output of the gas condensate increases until the pressure after the throttle reaches the range of values of 1.8 – 1.9 MPa. In this interval, the maximum specific condensate yield is achieved. With a further increase in the pressure drop on the throttle, the specific output of the gas condensate decreases. This is explained by the phenomenon of retrograde condensation, since the maximum condensation line is in the range of these pressures.Conclusion. Based on the results of the work, it was found that the developed software module can be used to solve the emerging series of problems. The results of the work show the suitability of the proposed method for practical purposes.
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Platonov, Vadim B., Marina N. Rumyantseva, Alexander S. Frolov, Alexey D. Yapryntsev, and Alexander M. Gaskov. "High-temperature resistive gas sensors based on ZnO/SiC nanocomposites." Beilstein Journal of Nanotechnology 10 (July 26, 2019): 1537–47. http://dx.doi.org/10.3762/bjnano.10.151.
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Increasing requirements for environmental protection have led to the need for the development of control systems for exhaust gases monitored directly at high temperatures in the range of 300–800 °C. The development of high-temperature gas sensors requires the creation of new materials that are stable under these conditions. The stability of nanostructured semiconductor oxides at high temperature can be enhanced by creating composites with highly dispersed silicon carbide (SiC). In this work, ZnO and SiC nanofibers were synthesized by electrospinning of polymer solutions followed by heat treatment, which is necessary for polymer removal and crystallization of semiconductor materials. ZnO/SiC nanocomposites (15–45 mol % SiC) were obtained by mixing the components in a single homogeneous paste with subsequent thermal annealing. The composition and microstructure of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The electrophysical and gas sensing properties of the materials were investigated by in situ conductivity measurements in the presence of the reducing gases CO and NH3 (20 ppm), in dry conditions (relative humidity at 25 °C RH25 = 0) and in humid air (RH25 = 30%) in the temperature range 400–550 °C. The ZnO/SiC nanocomposites were characterized by a higher concentration of chemisorbed oxygen, higher activation energy of conductivity, and higher sensor response towards CO and NH3 as compared with ZnO nanofibers. The obtained experimental results were interpreted in terms of the formation of an n–n heterojunction at the ZnO/SiC interface.
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Alvarez, Kelly, Soong Keun Hyun, and Hideo Nakajima. "Lotus-Type Porous Nickel-Free Stainless Steel with High Temperature Nitriding." Advanced Materials Research 15-17 (February 2006): 756–61. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.756.
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Lotus-type porous Fe-25wt.%Cr and Fe-23wt.%Cr-2wt.%Mo alloys were fabricated by continuous zone melting technique in pressurized hydrogen gas. After applying a high temperature nitriding treatment, the fabricated Lotus-type porous nickel-free stainless steel absorbed larger amount of nitrogen compared with non-porous alloy of the same composition since the surface area exposed to the gas is larger in the porous samples. In the Lotus-type porous Fe-25wt.%Cr and Fe-23wt.%Cr-2wt.%Mo alloys the nitrogen concentration after the nitriding achieved was approximately 1.2 wt.%. Only austenite peaks were detected in the profile of both Fe-Cr-N alloys after the nitriding treatment. Neither CrN nor Cr2N were identified by XRD in any specimen after the nitriding.
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Li, Junfeng, Shuting Zhuang, Liang Wang, and Jianlong Wang. "Treatment of Radioactive Wastewater from High-Temperature Gas-Cooled Reactor by Membrane System." Nuclear Technology 203, no. 1 (March 20, 2018): 101–7. http://dx.doi.org/10.1080/00295450.2018.1432838.
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Solar, Jon, Blanca Caballero, Isabel De Marco, Alexander López-Urionabarrenechea, and Naia Gastelu. "Optimization of Charcoal Production Process from Woody Biomass Waste: Effect of Ni-Containing Catalysts on Pyrolysis Vapors." Catalysts 8, no. 5 (May 4, 2018): 191. http://dx.doi.org/10.3390/catal8050191.
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Woody biomass waste (Pinus radiata) coming from forestry activities has been pyrolyzed with the aim of obtaining charcoal and, at the same time, a hydrogen-rich gas fraction. The pyrolysis has been carried out in a laboratory scale continuous screw reactor, where carbonization takes place, connected to a vapor treatment reactor, at which the carbonization vapors are thermo-catalytically treated. Different peak temperatures have been studied in the carbonization process (500–900 °C), while the presence of different Ni-containing catalysts in the vapor treatment has been analyzed. Low temperature pyrolysis produces high liquid and solid yields, however, increasing the temperature progressively up to 900 °C drastically increases gas yield. The amount of nickel affects the vapors treatment phase, enhancing even further the production of interesting products such as hydrogen and reducing the generated liquids to very low yields. The gases obtained at very high temperatures (700–900 °C) in the presence of Ni-containing catalysts are rich in H2 and CO, which makes them valuable for energy production, as hydrogen source, producer gas or reducing agent.
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Sozańska, Maria. "Transformations of Phases in Titanium Alloy after High Temperature Hydrogen Treatment." Solid State Phenomena 197 (February 2013): 168–73. http://dx.doi.org/10.4028/www.scientific.net/ssp.197.168.
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Positive nature of the effects of hydrogen on the properties of titanium alloys is manifested in the high temperature hydrogen treatment (HTM - Hydrogen Treatment of Materials), where hydrogen is temporary alloying component. The paper presents the results of the possibilities of hydrogen using as a temporary alloying element in Ti-6Al-4V alloy and titanium Grade 3. Treatment of hydrogen alloy consisted of three stages: hydrogenation in hydrogen gas atmosphere at 650°C, a cyclic hydrogen-treatment (3 cycles 850 °C to 250 °C) and a dehydrogenation in vacuum (550°C). It was shown that hydrogen affects appreciably changes the microstructure of surface layer of the tested titanium alloy. The aim of this work is to determine the effect of hydrogen on the two-phase microstructure in Ti-6Al-4V alloy and Grade 3 titanium and hardness after high temperature hydrogen treatment.
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Tao, Hongbo, and Shuai Song. "Study on the effect of high temperature heat treatment of H2 on the pore structure of activated carbon." Journal of Physics: Conference Series 2539, no. 1 (July 1, 2023): 012003. http://dx.doi.org/10.1088/1742-6596/2539/1/012003.
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Abstract As a high-quality adsorbent, activated carbon is widely used in air purification, natural gas storage, sewage treatment, gas enrichment, and separation, etc. The pore microstructure of activated carbon directly affects the adsorption capacity. In this paper, the altered in the microstructure of activated charcoal before and after high-temperature treatment were investigated by high-temperature thermal treatment of activated charcoal at 600°C and 700°C under an H2 atmosphere. The results of low-temperature (77 K) nitrogen adsorption showed that after high-temperature H2 heat treatment, the pores of activated carbon would be ablated and the pore structure would be significantly changed. The specific surface area, micropore specific surface area, total pore volume, and micropore pore volume all increased, and the degree of enhancement was proportional to the temperature of the heat treatment. The pore size distribution of activated charcoal before and after heat treatment was analyzed by density functional theory, and it was concluded that the pore volume of activated carbon mesopores (2-4 nm) increased significantly after high-temperature heat treatment, which could effectively improve the adsorption and separation capacity of activated carbon in larger molecular systems.
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Lowe, John B., and Richard T. Baker. "Deformation of Ordered Mesoporous Silica Structures on Exposure to High Temperatures." Journal of Nanomaterials 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/754076.
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Ordered mesoporous silica materials are of interest for a wide range of applications. In many of these, elevated temperatures are used either in the preparation of the material or during its use. Therefore, an understanding of the effect of high temperature treatments on these materials is desirable. In this work, a detailed structural study is performed on silicas with three representative pore structures: a 2-D hexagonal pore arrangement (SBA-15), a continuous 3D cubic bimodal pore structure (KIT-6), and a 3D large cage pore structure (FDU-12). Each silica is studied as prepared and after treatment at a series of temperatures between 300 and 900°C. Pore structures are imaged using Transmission Electron Microscopy. This technique is used in conjunction with Small-Angle X-ray Diffraction, gas physisorption, and29Si solid state Nuclear Magnetic Resonance. Using these techniques, the pore size distributions, the unit cell dimensions of the mesoporous structures, and the relative occupancy of the distinct chemical environments of Si within them are cross correlated for the three silicas and their evolution with treatment temperature is elucidated. The physical and chemical properties before, during, and after collapse of these structures at high temperatures are described as are the differences in behavior between the three silica structures.
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Turnbull, Matthew H., Richard P. Pharis, Leonid V. Kurepin, Michal Sarfati, Lewis N. Mander, and Dave Kelly. "Flowering in snow tussock (Chionochloa spp.) is influenced by temperature and hormonal cues." Functional Plant Biology 39, no. 1 (2012): 38. http://dx.doi.org/10.1071/fp11116.
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Snow tussocks (Chionochloa spp.) in New Zealand exhibit extreme mast (episodic) seeding which has important implications for plant ecology and plant–insect interactions. Heavy flowering appears to be triggered by very warm/dry summers in the preceding year. In order to investigate the physiological basis for mast flowering, mature snow tussock plants in the field and younger plants in a glasshouse and shadehouse were subjected to a range of manipulative treatments. Field treatments included combinations of warming, root pruning and applications of two native gibberellins (GAs) GA3, which is known to be highly floral inductive and GA4, which is associated with continued floral apex development in another long-day grass. Warming, GA3 alone and especially warming + GA3, significantly promoted flowering, as did applications of GA4 alone and GA4 + CCC (2-chloroethyltrimethylammonium chloride, which is a known synergist of GA3-induced flowering in the annual grass, Lolium temulentum L.). Our results provide support for the concept that mast flowering events in tussock species are causally related to high temperature-induced increases in endogenous gibberellin levels. It is likely that GAs (endogenous or applied) promote the continued development of a previously long-day induced floral apex. In addition to the promotion of flowering, applied GA3 also disturbed the plant’s innate resource threshold requirements, as shown by the death, over winter, of many non-flowering tillers. Applied GA4 did not show this effect, likely due to its rapid catabolic metabolism to an inactive form. High temperature-induced flowering mediated by elevated levels of endogenous floral-promotive GAs could have important implications for regulating the evolutionary interaction between these masting plants and their seed predators.
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Xu, Yan, Yinglai Liu, Fengping Yang, Zhenjun Feng, Qiang Bai, Yonggang Chang, Xianghui Nie, and Liang Li. "Study on Distribution of Heat Treatment Temperature Field of Long distance Oil and Gas Pipeline with High Steel Grade." Journal of Physics: Conference Series 2499, no. 1 (May 1, 2023): 012016. http://dx.doi.org/10.1088/1742-6596/2499/1/012016.
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Abstract In-service welding repair is important to ensure natural gas pipelines’ safe and reliable operation. The temperature distribution in the welding heat treatment process directly affects the pipeline’s bearing capacity and local stress distribution. This study studied the temperature distribution of a high steel pipeline generated by the heat treatment process for the long-term transportation of oil and gas was studied experimentally. The medium frequency induction heating method is applied to heat the tube body by winding a heating belt on the outer wall of the steel pipe to simulate pre-welding and post-welding heat treatment. At the same time, a thermocouple is used to record the temperature change of each position during the whole heating process to obtain data. Through numerical analysis and fitting, the distribution law of the temperature field in the heat treatment process of steel pipe is established to guide the field heating temperature control.
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Suprihanto, Agus. "Polarization Corrosion Test of Austenitic Stainless Steel 316L after High Temperature Gas Nitriding." ROTASI 20, no. 1 (January 2, 2018): 1. http://dx.doi.org/10.14710/rotasi.20.1.1-4.
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Austenitic stainless steel 316L is ones of popular metallic biomaterial for implant due to the good mechanical properties and corrosion resistance. However at corrosion media, highly stressed and oxygen-depleted environment, it still susceptible to corrosion. Various methods have been developed to enhance the corrosion resistance of stainless steel such as high temperature gas nitriding. High temperature gas nitriding for 316L has been successfully done. This process is conducted at temperature 1050, 1100 and 1200oC for 15 and 30 minutes before quenching in the water. Polarization corrosion test showed that the corrosion resistance was significant improved for treatment at temperature 1050oC and holding time 15 minutes.
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TRESSAUD, A., B. CHEVALIER, B. LEPINE, J. M. DANCE, L. LOZANO, J. GRANNEC, J. ETOURNEAU, R. TOURNIER, A. SULPICE, and P. LEJAY. "PASSIVATION PROCESS OF HIGH Tc SUPERCONDUCTORS YBa2Cu3O7−δ BY FLUORINE GAS TREATMENT." Modern Physics Letters B 02, no. 10 (November 1988): 1183–88. http://dx.doi.org/10.1142/s0217984988001119.
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The atmospheric degradation of high T c superconductors YBa 2 Cu 3 O 7−δ can be prevented using fluorine gas processings around room temperature. A thin layer of amorphous fluorides (and/or oxyfluorides) is formed at the surface of the particles, which passivates the material against hydrolysis and gas-exchange processes. A fluorination mechanism has been proposed, which can account for both fluorine analysis and weight uptake. The superconductivity onset does not seem to be affected by fluorination. Furthermore, an improvement of the shielding effect-Meissner effect cycle to 91% reversibility is achieved when F 2-treated oxides are heated at 350°C under vacuum.
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Wöllmer, Silke, Andrea Förg, Sebastian Schuster, and Patrick J. Masset. "Solvothermal Modified Layers against High Temperature Corrosion." Materials Science Forum 825-826 (July 2015): 621–27. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.621.
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Service and downtimes of waste incineration plants generate high expenses for their operators. State of the art is to protect high corrosion exposed components by cladding them with a nickel based alloy. The welded overlay is 2-3 mm thick and very expensive. It needs to be repaired at each service interval. An alternative coating consists of a thermal sprayed multilayer of a nickel based bondcoat and a ceramic topcoat. Thickness and costs of this multilayer are assumed to be in the range of about 10% of the currently used coating. A solvothermal treatment chemically densifies the coating. This leads to a significantly lower porosity whilst improving cohesion and hardness properties. This innovative process leads to a self-healing layer caused by the high temperature waste gas exposition as the driving force.
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Park, Sang-Jun, Jung-Min Kim, Hee-Jae Kang, Chang-Yong Kang, Yung-Hee Kim, and Jang-Hyun Sung. "Isothermal Heat Treatment of AISI 430 Ferritic Stainless Steel after High Temperature Gas Nitriding." Journal of the Korean Society for Heat Treatment 25, no. 3 (May 31, 2012): 115–20. http://dx.doi.org/10.12656/jksht.2012.25.3.115.
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Saelor, Kritsayanee, and Panyawat Wangyao. "Effect of Temperature Dropping during Solution Treatment in Rejuvenation Heat Treatment and its Long-Term Heating Simulation on Microstructures of Nickel Base Alloy, Udimet 520." Materials Science Forum 891 (March 2017): 25–32. http://dx.doi.org/10.4028/www.scientific.net/msf.891.25.
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Udimet 520 is a low precipitation strengthened nickel-based superalloy, which was designed and developed to be gas turbine blades at elevated temperatures. However, after long-term service under high stresses and temperatures, the microstructure of the turbine blades could be continually degraded. Therefore, the mechanical properties could be worse than the new ones. The rejuvenation heat treatment of degraded turbine blades, which were made of cast Udimet 520, was following by solution treatment at 1,121oC / 4 hours and then double aging processes including primary aging at 843 oC / 24 hours and secondary aging at 760oC / 16 hours, respectively. However, in practical reheat treatment processes, the temperature during solution treatment could be dropped by error or malfunction of high temperature heating furnace because the furnace has to be operated continually at very high temperature for very long time resulting in final reheat treated microstructures in many nickel base superalloys. To simulate this effect, the droppings of temperature during solution treatment are chosen and performed for 3 levels; 840oC, 800oC and 760oC, which could happen in practical working then heated up again immediately to solution temperature level. The maximum number of temperature dropping during the single solution treatment is up to 3 times. Received results show that the effect of temperature dropping during solution treatment has influenced on the final rejuvenated microstructures slightly due to the low precipitation behavior of the alloy. The long term heating at 800oC and 900oC / 1000 hours provided much effect in gamma prime particle coarsening.
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Yoda, Nobuhiro, Yuri Abe, Yuma Suenaga, Yoshiki Matsudate, Tomohiro Hoshino, Takehiko Sugano, Keisuke Nakamura, Akitoshi Okino, and Keiichi Sasaki. "Resin Cement–Zirconia Bond Strengthening by Exposure to Low-Temperature Atmospheric Pressure Multi-Gas Plasma." Materials 15, no. 2 (January 14, 2022): 631. http://dx.doi.org/10.3390/ma15020631.
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The purpose of this study was to investigate the effect of gas species used for low-temperature atmospheric pressure plasma surface treatment, using various gas species and different treatment times, on zirconia surface state and the bond strength between zirconia and dental resin cement. Three groups of zirconia specimens with different surface treatments were prepared as follows: untreated group, alumina sandblasting treatment group, and plasma treatment group. Nitrogen (N2), carbon dioxide (CO2), oxygen (O2), argon (Ar), and air were employed for plasma irradiation. The bond strength between each zirconia specimen and resin cement was compared using a tension test. The effect of the gas species for plasma irradiation on the zirconia surface was investigated using a contact angle meter, an optical interferometer, an X-ray diffractometer, and X-ray photoelectric spectroscopy. Plasma irradiation increased the wettability and decreased the carbon contamination on the zirconia surface, whereas it did not affect the surface topography and crystalline phase. The bond strength varied depending on the gas species and irradiation time. Plasma treatment with N2 gas significantly increased bond strength compared to the untreated group and showed a high bond strength equivalent to that of the sandblasting treatment group. The removal of carbon contamination from the zirconia surface and an increase in the percentage of Zr-O2 on the zirconia surface by plasma irradiation might increase bond strength.
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Gui, Fubing, Yong Huang, Menghan Wu, Xilai Lu, Yongming Hu, and Wanping Chen. "Aging Behavior and Heat Treatment for Room-Temperature CO-Sensitive Pd-SnO2 Composite Nanoceramics." Materials 15, no. 4 (February 12, 2022): 1367. http://dx.doi.org/10.3390/ma15041367.
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A high long-term stability is crucial for room-temperature gas-sensitive metal oxide semiconductors (MOSs) to find practical applications. A series of Pd-SnO2 mixtures with 2, 5, and 10 wt% Pd separately were prepared from SnO2 and Pd powders. Through pressing and sintering, Pd-SnO2 composite nanoceramics have been successfully prepared from the mixtures, which show responses of 50, 100, and 60 to 0.04% CO-20% O2-N2 at room temperature for samples of 2, 5, and 10 wt% Pd, respectively. The room-temperature CO-sensing characteristics were degraded obviously after dozens of days’ aging for all samples. For samples of 5 wt% Pd, the response to CO was decreased by a factor of 4 after 20 days of aging. Fortunately, some rather mild heat treatments will quite effectively reactivate those aged samples. Heat treatment at 150 °C for 15 min in air tripled the response to CO for a 20 days-aged sample of 5 wt% Pd. It is proposed that the deposition of impurity gases in air on Pd in Pd-SnO2 composite nanoceramics has resulted in the observed aging, while their desorption from Pd through mild heat treatments leads to the reactivation. More studies on aging and reactivation of room-temperature gas sensitive MOSs should be conducted to achieve high long-term stability for room-temperature MOS gas sensors.
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Volkov, Roman S., Ivan S. Voytkov, and Pavel A. Strizhak. "Temperature Fields of the Droplets and Gases Mixture." Applied Sciences 10, no. 7 (March 25, 2020): 2212. http://dx.doi.org/10.3390/app10072212.
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In this research, we obtain gas–vapor mixture temperature fields generated by blending droplets and high-temperature combustion products. Similar experiments are conducted for droplet injection into heated air flow. This kind of measurement is essential for high-temperature and high-speed processes in contact heat exchangers or in liquid treatment chambers, as well as in firefighting systems. Experiments are conducted using an optical system based on Laser-Induced Phosphorescence as well as two types of thermocouples with a similar measurement range but different response times (0.1–3 s) and accuracy (1–5 °C). In our experiments, we inject droplets into the heated air flow (first scheme) and into the flow of high-temperature combustion products (second scheme). We concentrate on the unsteady inhomogeneous temperature fields of the gas–vapor mixture produced by blending the above-mentioned flows and monitoring the lifetime of the relatively low gas temperature after droplets passes through the observation area. The scientific novelty of this research comes from the first ever comparison of the temperature measurements of a gas–vapor–droplet mixture obtained by contact and non-contact systems. The advantages and limitations of the contact and non-contact techniques are defined for the measurement of gas–vapor mixture temperature.
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Salmachi, Alireza, and Manouchehr Haghighi. "Temperature effect on methane sorption and diffusion in coal: application for thermal recovery from coal seam gas reservoirs." APPEA Journal 52, no. 1 (2012): 291. http://dx.doi.org/10.1071/aj11021.
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Investigating the effects of in situ thermal treatment on coal seams requires adequate knowledge of gas sorption and its kinetics in coal at various temperatures. Methane sorption onto two Australian coal samples (high-volatile bituminous) at dry state and different temperatures was measured. Methane adsorption isotherms were measured at pressures up to 7 MPa by the gas adsorption manometric method. Adsorption isotherms data at two temperatures were used to investigate the effects of in situ thermal treatment on critical desorption pressure, ultimate gas recovery and the diffusion coefficient in coal. An increase of experimental temperature from 308 to 348 K resulted in a 50% reduction in the adsorption affinity of the coal sample and an insignificant reduction in the saturation capacity of the isotherms. At higher experimental temperatures, Langmuir isotherms exhibit downward shift with the initial gas content of the coal seam being constant, resulting in critical gas desorption pressure increase. According to the measured Langmuir isotherms at different temperatures, an increase in reservoir temperature by 1 K leads to a 2% and 1.2% increase in total recovery for the tested coal seams. Gas left in the coal seam at the abandonment pressure can only be recovered at a higher reservoir temperature. Diffusion coefficients of coal seam samples were calculated for different experimental temperatures. Fractional uptakes of the first coal sample show a good agreement with the results obtained using the unipore diffusion model with the diffusion coefficient to be 4.7 × 10–12 m2/s at 348 K. For the second coal sample, the unipore diffusion model fairly matches the uptake data. A bidisperse diffusion model was also applied to measure the adsorption kinetics of the second coal sample, resulting in an improved agreement with the experimental uptake data. Both coal samples exhibited a reduction of the diffusion coefficient with an increase in equilibrium pressure; this effect was more pronounced at equilibrium pressures below 0.045 MPa. It was observed that the diffusion coefficient change with pressure becomes flat at high pressures, with the pressure effect diminishing much faster at lower temperatures.
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Cao, Lihu, Jinsheng Sun, Jianyi Liu, and Jiquan Liu. "Experiment and Application of Wax Deposition in Dabei Deep Condensate Gas Wells with High Pressure." Energies 15, no. 17 (August 26, 2022): 6200. http://dx.doi.org/10.3390/en15176200.
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The Dabei deep high-pressure condensate gas field occupies the paramount position in the Tarim Oilfield in China, the exploration and developments of which have been progressing. Since the initial development, the wax deposition and plugging in the wellbore and gathering pipeline have been the most bothering issues, resulting in the reduction or even shutdown of condensate gas well production. Therefore, the wax appearance temperature of Dabei condensate oil was studied using the capillary viscometer, differential scanning calorimetry (DSC), and polarizing microscope observation. The wax content was tested by using the DSC and crystallization separation test method. Finally, the wax appearance temperatures of degassed condensate oil and equilibrium condensate oil under different pressures were tested. Experimental results show that the wax appearance temperature measured by polarizing microscope observation was higher than that measured by the DSC and capillary viscometer, the lag of which can be recorded as the cloud point. The wax appearance temperature measured by polarizing microscope observation is of high accuracy. Secondly, the DSC method is not sufficient for measuring wax precipitation at low temperatures, showing a lower wax content than the crystallization separation test method. Thus, the wax content of Dabei condensate oil can be better measured by using the crystallization separation test method. Additionally, the wax precipitation law of equilibrium condensate oil is opposite to that of degassed condensate oil. The wax appearance temperature of equilibrium condensate oil increases as the pressure decreases. The results of wax appearance temperature of equilibrium condensate oil provide a useful and quick index to judge the potential risk of wax precipitation in the Tarim Oilfield, which can provide an efficient strategy for the development of waxy condensate gas reservoirs and the optimization of wax prevention and treatment technology.
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Kao, Wen-Hsien, Yean-Liang Su, Jeng-Haur Horng, and Shu-Er Yang. "Tribological performance, electrochemical behavior and biocompatibility of high-temperature gas-nitrided Ti6Al4V alloy." Industrial Lubrication and Tribology 70, no. 8 (November 12, 2018): 1536–44. http://dx.doi.org/10.1108/ilt-02-2017-0037.
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Purpose This paper aims to investigate the tribology, corrosion resistance and biocompatibility of high-temperature gas-nitrided Ti6Al4V alloy. Design/methodology/approach The tribological properties were studied by reciprocating wear tester. The corrosion resistance was evaluated by using potentiodynamic polarization test. The purified mouse leukaemic monocyte macrophage cells are used to investigate the biocompatibility. Findings The results show that the nitriding treatment leads to a significant improvement in the hardness and tribological properties of Ti6Al4V alloy. Specifically, compared to untreated Ti6Al4V, the hardness increases from 3.24 to 9.02 GPa, while the wear rate reduces by 12.5 times in sliding against a Ti6Al4V cylinder and 19.6 times in sliding against a Si3N4 ball. Furthermore, the nitriding treatment yields an improved corrosion resistance and a biocompatibility similar to that of untreated Ti6Al4V. Originality/value The nitrided Ti6Al4V alloy is an ideal material for the fabrication of load-bearing artificial implants.
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Bai, Liuyang, Yuge Ouyang, Hongbing Wang, Min Wang, and Fangli Yuan. "Off-gas detection and treatment for green air-plasma process." Green Processing and Synthesis 11, no. 1 (January 1, 2022): 965–73. http://dx.doi.org/10.1515/gps-2022-0082.
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Abstract Thermal plasma is a promising technology widely used in materials processing and waste treatment due to its unique properties including high temperature, high energy density, high chemical activity, and high quench rate. Air-plasma is preferentially used because air is of low price as plasma gas. The content of NO x in off-gas from air-plasma was determined using a gas analyzer, and a treatment unit was designed for the green air-plasma process. Results show that the concentration of NO x in off-gas from air-plasma was 2,489 and 9,112 ppm when the plasma input power was 50 and 150 kW, respectively. O2 in the off-gas would act as an oxidant to promote NO x absorption; thus, alkali absorption method was directly used for the treatment of the present off-gas from air-plasma. The absorption efficiency could be increased to 62.2% when additional O2 was provided into the off-gas to change its O2 content from 20% to 50%. The absorption rate was estimated based on the experimental data and a multistage absorption unit design, which could be reduced below 100 ppm and meet the emission standard. This article presents the feasibility of thermal plasma off-gas purification, so as to truly realize the green plasma process.
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Fujikawa, Hisao, and Takanori Watanabe. "Advanced Surface Hardening Techniques Using Gas Process." Solid State Phenomena 118 (December 2006): 161–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.118.161.
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Air Water Incorporated Japan (AWI) has succeeded in developing and commercializing new surface treatment technologies. One of them is the NV Nitriding process. Through an activation treatment using fluorine-based gas for the surface treatment of metals before the nitriding treatment, it is possible to remove the oxide film, such as the passive film, formed on stainless steels and Ni-based alloys and also to nitride these alloys on a mass-production scale. The activation effect afforded by fluoride enables nitriding at a temperature about 150°C lower than other conventional processes, achieving minimal thermal deformation and strain. Also, with this activation process, the range of selection of nitriding conditions such as temperature, gas composition and heat pattern has been considerably extended to enable the formation of a nitride layer optimum for the required characteristics of the treated metals. That is, this process can control the thickness of the nitride compound layer. NV Pionite treatment also has been developed as the soluble carbon diffusion process by which to ensure high corrosion resistance and high hardness in austenitic stainless steels using the above activation treatment.
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Kasprzak, W., Daryoush Emadi, Mahi Sahoo, and Maria Aniolek. "Development of Aluminium Alloys for High Temperature Applications in Diesel Engines." Materials Science Forum 618-619 (April 2009): 595–600. http://dx.doi.org/10.4028/www.scientific.net/msf.618-619.595.
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Rapid penetration of diesel engines is expected in North America because of their better fuel efficiency and lower greenhouse gas (GHG) emissions. Diesel engine components, particularly cylinder heads, are made of cast irons and replacing them with aluminium alloys could result in a significant weight reduction and consequently better fuel efficiency. Aluminum alloys for diesel engine applications need to withstand higher operating temperatures and pressures as compared to conventional 3xxx based alloys that lose strength above 150oC. This paper presents selected results pertaining to alloy development with improved high temperature performance based on the modified 356 composition. Such alloys with engineered chemical composition and properly designed heat treatment could have improved properties at temperatures up to 250oC. The advanced thermal analysis techniques including dilatometer analysis were used to determine the effect of alloying additions on thermal characteristics including aging kinetics and its impact on casting service performance. Selected structure analysis results including XRD and TEM/EDX as well as elevated temperature tensile testing are presented.
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Bond-Lamberty, Ben, A. Peyton Smith, and Vanessa Bailey. "Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils." Biogeosciences 13, no. 24 (December 21, 2016): 6669–81. http://dx.doi.org/10.5194/bg-13-6669-2016.
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Abstract. Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO2 and CH4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q10) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH4 fluxes. The cumulative production of C from CO2 was over 6 orders of magnitude higher than that from CH4; cumulative CO2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52–73 % lower C. Cumulative CH4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.
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Rojhirunsakool, Tanaporn, Duangkwan Thongpian, Nutthita Chuankrerkkul, and Panyawat Wangyao. "Effect of Pre-Weld Heat Treatment Temperatures on TIG Welded Microstructures on Nickel Base Superalloy, GTD-111." Key Engineering Materials 658 (July 2015): 14–18. http://dx.doi.org/10.4028/www.scientific.net/kem.658.14.
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Nickel-base superalloys have been used as high temperature materials in land-base gas turbine application. When subjected to long term, high temperature service, large crack propagation was observed. Typical refurbishment method of these turbines is carried out by using TIG welding followed by post-weld standard heat treatment. However, new crack initiation is found in the heat-affected zone after TIG welding. Pre-weld heat treatment has been discovered to improves final γ + γ’ microstructure. This study focuses on the effect of pre-weld heat treatment temperature on final γ + γ’ microstructure. Seven different conditions of pre-weld heat treatment temperature were investigated. Scanning electron microscopy studies were carried out after pre-weld and post-weld heat treatments to compare the γ + γ’ microstructure and capture microcracks. The best pre-weld heat treatment temperature produces uniform distribution of finely dispersed γ’ precipitates in the γ matrix without post-weld crack.
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Ma, Jianyu, Mehdi Mahmoodinia, Kumar R. Rout, and Edd A. Blekkan. "The Impact of Operating Parameters on the Gas-Phase Sulfur Concentration after High Temperature Sulfur Sorption on a Supported Mo-Mn Sorbent." Reactions 2, no. 4 (September 23, 2021): 365–73. http://dx.doi.org/10.3390/reactions2040023.
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The impact of operating parameters on H2S capture from a syngas mixture by a Mo-promoted Mn-based high-temperature sorbent was investigated. The parameters investigated included temperature, space velocity, H2S concentration in the feed gas, and steam content. The H2S and SO2 concentrations in the gas after passing over a bed of the sorbent were analyzed and compared with thermodynamic calculations. The results confirmed that low temperature, low space velocity, low H2S concentration, and a dry feed were favorable for achieving a low residual concentration of sulfur compounds in the effluent gas. The sorbent was able to reduce the residual H2S concentration to below 1 ppm under all tested conditions. However, the unavoidable steam content in the gas phase had a significant adverse effect on sulfur removal from the gas. An empirical model, containing the three variables, i.e., temperature, space velocity, and H2S concentration in the feed, was developed and can be used to predict the effluent H2S residual concentration after treatment by the 15Mn8Mo sorbent.
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Zheng, Lei, Wei Wang, and Kan Wang. "On-the-fly temperature-dependent cross section treatment under extremes in RMC code." EPJ Web of Conferences 239 (2020): 22009. http://dx.doi.org/10.1051/epjconf/202023922009.
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Neutron transport relevant to inertial confinement fusion always involves extremes, in which the physical quantities are extremely high, widely distributed and changes rapidly with space and time. In order to solve the memory and efficiency problems in nuclear data storage and processing, the on-the-fly temperature-dependent cross section treatment technique was investigated and developed under extremes in RMC code. Different strategies were adopted for different energy regions, i.e., the free gas model in the thermal region, the TMS method with 0K basis cross section temperature in the resolved resonance region, and the infinite dilution cross section in the unresolved resonance region, whereas the high energy region above the unresolved resonance region was not treated currently. The test results of Godiva sphere and plutonium sphere show that the on-the-fly technique has high accuracy, but the efficiency of the proposed technique still needs to be improved for some cases, and the optimization work with the elevated basis cross section temperatures is ongoing.
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Farahdila, K., P. S. Goh, A. F. Ismail, N. F. W. M. Wan, H. M. H. Mohd, W. K. Soh, and S. Y. Yeo. "Challenges in Membrane Process for Gas Separation from Natural Gas." Journal of Applied Membrane Science & Technology 25, no. 2 (July 7, 2021): 89–105. http://dx.doi.org/10.11113/amst.v25n2.222.
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Membrane technology is cost effective solution for CO2 removal from natural gas. However, there is challenges during its application depending on the polymer material characteristic. Understanding on the polymer fundamental and transport properties, will enable proper design of pre-treatment and operating conditions that suits its capability envelope. Diffusivity selective membrane favors high pressure and high temperature conditions and vice versa for solubility selective polymer. On top of that, the robustness and durability of the resultant membrane, need to be evaluated with multicomponent mixture to understand the effect of competitive sorption, plasticization and aging phenomena that will seriously impacting the membrane performance during its application.
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Bespala, E. V., A. O. Pavliuk, and S. G. Kotlyarevskiy. "INFLUENCE OF GAS DYNAMICS OF HIGH TEMPERATURE FLOW ON THE TREATMENT EFFICIENCY OF NUCLEAR GRAPHITE." Alternative Energy and Ecology (ISJAEE), no. 23 (April 24, 2016): 19–25. http://dx.doi.org/10.15518/isjaee.2015.23.002.
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Lee, H. W., J. H. Kong, D. J. Lee, H. Y. On, and J. H. Sung. "A study on high temperature gas nitriding and tempering heat treatment in 17Cr–1Ni–0.5C." Materials & Design 30, no. 5 (May 2009): 1691–96. http://dx.doi.org/10.1016/j.matdes.2008.07.023.
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Rubaiee, Saeed. "High sour natural gas dehydration treatment through low temperature technique: Process simulation, modeling and optimization." Chemosphere 320 (April 2023): 138076. http://dx.doi.org/10.1016/j.chemosphere.2023.138076.
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Heinz, P., K. Juckelandt, and S. Lutz. "Combined CFD and Heat Treatment Simulation of High-Pressure Gas Quenching Process." HTM Journal of Heat Treatment and Materials 78, no. 5 (October 1, 2023): 276–87. http://dx.doi.org/10.1515/htm-2023-0002.
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Abstract To improve the process development for high pressure gas quenching a digital quenching simulation model combining the fields of computational fluid dynamics and heat treatment process simulation has been developed. It was found that the gas flow and hence the quenching properties depend on both local (geometry of parts, carrier and chamber) as well as global influencing factors (fan characteristics, system pressure and hydraulic resistances). Therefore, a computational fluid dynamics model that includes all these factors was realized. The approach includes a heat transfer analysis to determine the local heat exchange coefficients on a component level. By connecting the computational fluid dynamics model and heat treatment simulation the local quenching characteristics are used to compute the temperature history of the quenched part. Based on a thermo-metallurgical heat treatment simulation the computed local cooling curves and metallurgical phase compositions are used to accurately predict the part properties like microstructure and hardness. The applicability of the model has been confirmed by hardness measurements. Hardness results for different batch positions, batch setups or tray systems can now be computed enabling an efficient virtual development of the gas quenching process.
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Abbas, Arwa Saud, Abdulrhman Faraj M. Hiazaa, Abdullah Jalalah, Mohammed Alkhamisah, Rasheed Alrasheed, Fadhl S. Alfadhl, Ghadeer H. Aljalham, and Fatimah Basem. "Fabrication Method of Carbon-based Materials in CH4/N2 Plasma by RF-PECVD and Annealing Treatment for Laser Diodes." Advanced Nano Research 6, no. 1 (September 18, 2023): 29–43. http://dx.doi.org/10.21467/anr.6.1.29-43.
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The present research addresses the synthesis of carbon materials thin films by RF-PECVD in N2/CH4 gas mixture. Carbon materials film was formed at 40/48 sccm of CH4/N2 of the total gas flow rate ratio CH4/CH4+N2 = 0.45 and 200/100 W HF/LF power at a deposition temperature of 350 oC and 1000 mTorr pressure. Then, post-annealing of carbon materials film took place at 400 oC by means of RTA under N2 flow. The formation of carbon nanostructures was investigated by scanning electron microscopy, energy dispersive X-ray, Raman spectroscopy, and atomic force microscopy, respectively. AFM shows that the films consisted of nanocrystalline grains. The surface morphology and structural characteristics of materials were studied as a gas flow function and substrate temperature. EDX results indicated the carbon presence, and Raman spectroscopy analysis revealed two broad bands: D-band 1381.64 cm−1 and G-band 1589.42 cm−1. The temperature-dependent post-annealing of carbon materials plays a key role in the graphite crystallites growth at high substrate temperatures. Our results indicate carbon materials incorporation for laser diode applications.
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Kosakivska, I. V. "GIBBERELLINS IN REGULATION OF PLANT GROWTH AND DEVELOPMENT UNDER ABIOTIC STRESSES." Biotechnologia Acta 14, no. 2 (February 2021): 5–18. http://dx.doi.org/10.15407/biotech14.02.005.
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Background. Gibberellins (GAs), a class of diterpenoid phytohormones, play an important role in regulation of plant growth and development. Among more than 130 different gibberellin molecules, only a few are bioactive. GA1, GA3, GA4, and GA7 regulate plant growth through promotion the degradation of the DELLA proteins, a family of nuclear growth repressors – negative regulator of GAs signaling. Recent studies on GAs biosynthesis, metabolism, transport, and signaling, as well as crosstalk with other phytohormones and environment have achieved great progress thanks to molecular genetics and functional genomics. Aim. In this review, we focused on the role of GAs in regulation of plant gtowth in abiotic stress conditions. Results. We represented a key information on GAs biosynthesis, signaling and functional activity; summarized current understanding of the crosstalk between GAs and auxin, cytokinin, abscisic acid and other hormones and what is the role of GAs in regulation of adaptation to drought, salinization, high and low temperature conditions, and heavy metal pollution. We emphasize that the effects of GAs depend primarily on the strength and duration of stress and the phase of ontogenesis and tolerance of the plant. By changing the intensity of biosynthesis, the pattern of the distribution and signaling of GAs, plants are able to regulate resistance to abiotic stress, increase viability and even avoid stress. The issues of using retardants – inhibitors of GAs biosynthesis to study the functional activity of hormones under abiotic stresses were discussed. Special attention was focused on the use of exogenous GAs for pre-sowing priming of seeds and foliar treatment of plants. Conclusion. Further study of the role of gibberellins in the acquisition of stress resistance would contribute to the development of biotechnology of exogenous use of the hormone to improve growth and increase plant yields under adverse environmental conditions.