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Journal articles on the topic 'Porosité hydrogène'

Author: Grafiati

Published: 25 May 2024

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1

TIMOFEEVА, A. S., A. A. KOZHUKHOV, T. V. NIKITCHENKO, and S. N. NEMYKIN. "THE EFFECT OF THE POROSITY OF HOT-BRIQUETTED IRON ON THE RELEASE OF HYDROGEN DURING SECONDARY OXIDATION WITH WATER OF DIFFERENT TEMPERATURES." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 78, no. 4 (May 11, 2022): 322–29. http://dx.doi.org/10.32339/0135-5910-2022-4-322-329.

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During storage and transportation of the metallized product, moisture may enter it, resulting its oxidation occurring with the release of hydrogen. When delivering the product by sea, this can lead to fire and explosive situation. It is noted that the physicochemical properties of the metallized product, such as density, porosity, chemical composition, temperature, etc., have a great influence on the release of hydrogen. The purpose of this work is to determine the dependence of hydrogen release during iron oxidation in the metallized briquettes on their porosity and the temperature of the humidifying water. The results of study of the effect of porosity on the density of HBI are presented; the limits of changes in closed and open porosity and their effect on density were determined. It is shown that the bulk density of briquettes decreases with an increase in the porosity of HBI. The experiments were performed in order to determine the dependence of hydrogen release upon contact of briquettes with distilled water on the porosity and water temperature. It was found that with an increase in the open porosity of briquettes, their moisture saturation increases and the release of hydrogen increases. A change in the temperature of water that reacts with iron affects the release of hydrogen, but it practically does not affect the release rate within the parameters studied. When transporting the metallized briquettes it is recommended to take into account the effect of their open porosity on the intensity of hydrogen release in contact with moisture.

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2

Li, Wen Qiong, Xiang Ming Li, Qing Lin Jin, and Rong Zhou. "Evolution of Porosity in Lotus-Type Porous Copper Fabricated by Continuous Casting Technique." Applied Mechanics and Materials 278-280 (January 2013): 433–36. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.433.

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Lotus-type porous copper materials were fabricated by continuous casting technique. The relationship between porosity and external pressure were developed based on the solute mass conservation law. Theoretical values of porosity are in agreement with our experimental results. Results show that porosity decreases when the partial pressure of hydrogen increases for cases of no pressure of argon above melt, while porosity first increases and then decreases as the partial pressure of hydrogen increases for case of nonzero pressure of argon above melt.

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3

Kotian, Ravindra, Madhu Keshava Bangera, Karen Boaz, and Prashanthi S. Madhyastha. "Effect of plasma gas atmosphere on hydroxyapatite-coated titanium-based implants." Metallurgical Research & Technology 118, no. 1 (November 30, 2020): 103. http://dx.doi.org/10.1051/metal/2020072.

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The study was designed to understand the influence of different atmospheres of plasma gas on hydroxyapatite-coated commercially pure Titanium (Ti) and titanium alloy (Ti-6Al-4V). Ti and Ti-6Al-4V were plasma spray-coated with hydroxyapatite in argon, nitrogen, argon/hydrogen, and nitrogen/hydrogen atmospheres. The microstructure, porosity, calcium to phosphate (Ca-P) ratio, surface roughness, and hardness of the coat were characterized using a scanning electron microscope, energy dispersive spectroscopy, image analyzer, profilometer, and Vickers hardness tester. The analyses of the coatings obtained in different plasma gas atmospheres showed variation in microstructure, morphology, porosity, surface roughness, and hardness. As the enthalpy decreased, an increase in porosity was observed in nitrogen/hydrogen, nitrogen, argon/hydrogen, and argon atmospheres, respectively. Peak Ca-P ratio was observed in argon, which is the most inert atmosphere compared to other tested plasma atmospheres. Atmospheres with high enthalpy presented an even surface with comparatively low surface roughness. Hardness value decreased with increasing porosity. The plasma gas atmosphere has a significant influence on Ca-P ratio, porosity, and microcracks of hydroxyapatite-coated oral implants.

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4

Cao, Rong, and Qing Lin Jin. "Theoretical Analysis of Porosity in an Ordered Porous Copper Fabricated by Continuous Unidirectional Solidification." Materials Science Forum 933 (October 2018): 136–41. http://dx.doi.org/10.4028/www.scientific.net/msf.933.136.

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Ordered porous copper with elongated pores has been fabricated by a continuous unidirectional solidification method in a hydrogen gas atmosphere with high pressure. The porosity of the ordered porous copper is significantly affected by the pressure of hydrogen. A theoretical model is developed to get the relation between the porosity and the processing parameters. The calculated values are in good agreement with the experimental results. Key words: Unidirectional solidification; Ordered porous copper; Porosity; Modeling.

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5

Bechelany, Mikhael, Adib Abou Chaaya, Fabien Frances, Ouardia Akdim, Didier Cot, Umit B. Demirci, and Philippe Miele. "Nanowires with controlled porosity for hydrogen production." J. Mater. Chem. A 1, no. 6 (2013): 2133–38. http://dx.doi.org/10.1039/c2ta00794k.

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6

Dispinar, D., S. Akhtar, A. Nordmark, M. Di Sabatino, and L. Arnberg. "Degassing, hydrogen and porosity phenomena in A356." Materials Science and Engineering: A 527, no. 16-17 (June 2010): 3719–25. http://dx.doi.org/10.1016/j.msea.2010.01.088.

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7

Ide, Takuya, Masakazu Tane, and Hideo Nakajima. "Fabrication of Lotus-Type Porous NiAl and Ni₃Al Intermetallic Compounds." Solid State Phenomena 124-126 (June 2007): 1721–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1721.

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Lotus-type porous NiAl and Ni3Al intermetallic compounds, possessing cylindrical pores aligned in the direction parallel to the solidification direction, were fabricated by using a unidirectional solidification technique in a pressurized hydrogen atmosphere of 2.5MPa. The porosity of lotus NiAl is 24.2 %, and the porosity of lotus Ni3Al is 3.2%; the porosity of the porous NiAl is larger than that of Ni3Al. This is because the solubility gap of hydrogen between liquid and solid phases of NiAl is larger than that of Ni3Al.

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8

BARRAZA, ALEXYIA M., CARL EDWARD CROSS, CHRISTOPHER JASON STULL, JESSE N. MARTINEZ, and CAROLIN FINK. "Applying In-Situ Radiography to Study Porosity Formation in Aluminum Welds." Welding Journal 102, no. 1 (January 1, 2023): 1–12. http://dx.doi.org/10.29391/2023.102.001.

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In-situ radiographic aluminum welding experiments were set up to observe the porosity formation and movement in aluminum weld pools. Aluminum Alloys 1100, 4047, and 6061 were autogenously gas tungsten arc welded while digitally recording radiograph images of macropores. Hydrogen was added in controlled parts per million through an argon-hydrogen shielding gas. The shielding gas hydrogen varied between 0 and 1000 parts per million of hydrogen, and three travel speeds were tested: 1.69, 2.54, and 3.39 mm/s. The transfer of hydrogen from the arc plasma to the weld pool was characterized using postweld gravimetric measurements to get the total pore volume and calculate weld metal hydrogen content. The amount of hydrogen added through the shielding gas played an important role in macropore volume and growth rate. Welding travel speed likewise played a critical role in hydrogen pickup. Alloy 1100 macropores originated at the bottom of the weld pool and then migrated upward toward the rear of the pool. Macropores in Alloys 4047 and 6061 originated at the leading edge of the weld pool and then moved downward and toward the rear of the pool. It is hypothesized that this difference in behavior is related to Marangoni-controlled fluid flow in Alloys 4047 and 6061.

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9

Muhammad Shahrul Nizam Shahrin, Norazila Othman, Nik Ahmad Ridhwan Nik Mohd, Mastura Ab Wahid, and Mohd Zarhamdy Md. Zain. "Porosity Effect of the Silver Catalyst in Hydrogen Peroxide Monopropellant Thruster." CFD Letters 13, no. 12 (December 17, 2021): 1–20. http://dx.doi.org/10.37934/cfdl.13.12.120.

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In monopropellant system, hydrogen peroxide is used with catalyst to create an exothermic reaction. Catalyst made of silver among the popular choice for this application. Since the catalyst used is in porous state, the effect of its porosity in the hydrogen peroxide monopropellant thruster performances is yet unknown. The porosity changes depending on factors including catalyst pact compaction pressure, bed dimension, and type of catalyst used. As researches on this topic is relatively small, the optimum porosity value is usually left out. The performance of the thruster indicated by the pressure drop across the catalyst bed. Porosity of the catalyst bed adds additional momentum sink to the momentum equation that contributes to the pressure gradient which lead to pressure loss inside thruster. The effect of porosity influences the performance and precision of the thruster. Study of the pressure drop by the catalyst bed requires a lengthy period and expensive experiments, however, numerical simulation by mean of Computational Fluid Dynamics (CFD) can be an alternative. In this paper, 90 wt% hydrogen peroxide solution with silver catalyst is studied in order to investigate the influence of porosity to the performances of the thruster, and to find the optimum porosity of the thruster. Species transport model is applied in the single-phase reaction simulation using the EDM for turbulence-chemistry interaction. Through this study, the effect of porosity towards the thruster performances represented in term of pressure drop, exit velocity, bed temperature, and thrust, and porosity of 0.4 found to be as an optimal value.

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10

Dudun, Anireju, Yin Feng, and Boyun Guo. "Numerical Simulation of Hydrogen Diffusion in Cement Sheath of Wells Used for Underground Hydrogen Storage." Sustainability 15, no. 14 (July 11, 2023): 10844. http://dx.doi.org/10.3390/su151410844.

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The negative environmental impact of carbon emissions from fossil fuels has promoted hydrogen utilization and storage in underground structures. Hydrogen leakage from storage structures through wells is a major concern due to the small hydrogen molecules that diffuse fast in the porous well cement sheath. The second-order parabolic partial differential equation describing the hydrogen diffusion in well cement was solved numerically using the finite difference method (FDM). The numerical model was verified with an analytical solution for an ideal case where the matrix and fluid have invariant properties. Sensitivity analyses with the model revealed several possibilities. Based on simulation studies and underlying assumptions such as non-dissolvable hydrogen gas in water present in the cement pore spaces, constant hydrogen diffusion coefficient, cement properties such as porosity and saturation, etc., hydrogen should take about 7.5 days to fully penetrate a 35 cm cement sheath under expected well conditions. The relatively short duration for hydrogen breakthrough in the cement sheath is mainly due to the small molecule size and high hydrogen diffusivity. If the hydrogen reaches a vertical channel behind the casing, a hydrogen leak from the well is soon expected. Also, the simulation result reveals that hydrogen migration along the axial direction of the cement column from a storage reservoir to the top of a 50 m caprock is likely to occur in 500 years. Hydrogen diffusion into cement sheaths increases with increased cement porosity and diffusion coefficient and decreases with water saturation (and increases with hydrogen saturation). Hence, cement with a low water-to-cement ratio to reduce water content and low cement porosity is desirable for completing hydrogen storage wells.

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11

Huang, Wen Zhan, Hong Jie Luo, Li Zhang, Yong Liang Mu, and Xin Cui. "Magnesium-Based Foam Biomaterials and their Related Properties." Materials Science Forum 933 (October 2018): 282–90. http://dx.doi.org/10.4028/www.scientific.net/msf.933.282.

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The magnesium-based foam biomaterials were prepared by melt foaming process, where Mg-Ca alloy was used as matrix material, hydroxyapatite (HA) as tackifier, MgCO3as foaming agent. The magnesium-based foam biomaterials with uniform structure were used for testing to investigate their compressive and biodegradable behaviors. The biodegradable property of the magnesium-based foam was mainly characterized by microstructure observation and hydrogen evolution. The results showed that the porosity of the magnesium-based foam has a more important impact on yield stress and plateau stress of compressive curves compared to HA content or its size. Corrosion rate of the magnesium-based foams decreases with increasing HA addition. Meanwhile, the porosity of the magnesium-based foams also has a very obvious effect on hydrogen evolution, i.e., the hydrogen evolution rate increases with decreasing the porosity of magnesium-based foams.

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12

Liu, Ming, Hai Jun Wang, Yi Jiang, Yong Ming Guo, and Ya Nan Song. "Optimization of Supersonic Plasma Spraying Parameters Based on Coating Porosity." Applied Mechanics and Materials 271-272 (December 2012): 86–91. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.86.

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In this paper, an optimization experiment was designed to get the optimal performance of supersonic sprayed coating. Response surface methodology based on Box-Behnken design has been used in this experimental design. Input factors were designed with four representative spraying parameters: powder feed rate, spraying power, argon flow rate and hydrogen flow rate. Porosity of NiCrBSi coating, as the only measured response, was applied to estimate the influence of spraying process on the coating performance. Results indicate that porosity is the most sensitive to change powder feed rate, followed by argon flow rate, hydrogen flow rate and spraying power. A minimum porosity of 1.8% was obtained under the optimization spraying parameters.

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13

Fortini, Arthur J., and Daniel D. Perlmutter. "Porosity effects in hydrogen reduction of iron oxides." AIChE Journal 35, no. 8 (August 1989): 1245–52. http://dx.doi.org/10.1002/aic.690350803.

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14

Ismailov, M. B., Zh M. Ramazanova, G. B. Nigmetchanova, S. Tolendyuly, and L. M. Mustafa. "Effect of the Porosity Ran ge and its Nature on Mechanical Properties of Magnesium Alloys Mg-Al-Zn." Eurasian Chemico-Technological Journal 18, no. 1 (June 17, 2016): 67. http://dx.doi.org/10.18321/ectj398.

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The possibilities of porosity adjustment in alloys of the Mg-Al-Zn system obtained by melting under a layer of flux were studied. The elements that significantly increase corrosion resistance and heat resistance, and improve mechanical strength and technological characteristics were chosen as doping components. Measurements showed that the range of porosity varied between 5.9 and 14.8%, and the relationship<br />between porosity and strength of alloys was defined for the first time for this range. For an alloy with porosity of 14.8%, the percentage of open pores was 12.8% while the percentage of closed pores was 2%. Micro-hardness of alloys with the given porosity was 661 MPa after casting, 876 MPa after homogenizing annealing and 897 MPa after artificial aging. The tensile strength was 235 MPa. Analysis identified that the main cause of porosity was catching atoms of hydrogen from atmosphere by molten alloys during melting, casting and liquation. In order to reduce the percentage of porosity alloys were doped by metal manganese, liquid metal was processed by calcium and hexachloroethane, and casting form was treated by boron nitride. These manipulations resulted in reduction of samples porosity up to 5.9%, increase of tensile strength up to 240 MPa. Open porosity was 4.5%, while closed porosity was 1.4%. At the same time micro-hardness of cast samples was 867 MPa, 903 MPa after homogenization annealing and 961 MPa after artificial aging. Further reduction of porosity and increasing of magnesium alloys strength is possible with the use of inert gases or vacuum melting. Samples porosity can be increased by more than 14.8% with the help of melting in the hydrogen containing atmosphere.

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15

Hegedüs, Nikolett, Riku Lovics, Miklós Serényi, Zsolt Zolnai, Péter Petrik, Judit Mihály, Zsolt Fogarassy, Csaba Balázsi, and Katalin Balázsi. "Examination of the Hydrogen Incorporation into Radio Frequency-Sputtered Hydrogenated SiNx Thin Films." Coatings 11, no. 1 (January 6, 2021): 54. http://dx.doi.org/10.3390/coatings11010054.

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In this work, amorphous hydrogen-free silicon nitride (a-SiNx) and amorphous hydrogenated silicon nitride (a-SiNx:H) films were deposited by radio frequency (RF) sputtering applying various amounts of hydrogen gas. Structural and optical properties were investigated as a function of hydrogen concentration. The refractive index of 1.96 was characteristic for hydrogen-free SiNx thin film and with increasing H2 flow it decreased to 1.89. The hydrogenation during the sputtering process affected the porosity of the thin film compared with hydrogen-free SiNx. A higher porosity is consistent with a lower refractive index. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of 4 at.% of bounded hydrogen, while elastic recoil detection analysis (ERDA) confirmed that 6 at.% hydrogen was incorporated during the growing mechanism. The molecular form of hydrogen was released at a temperature of ~65 °C from the film after annealing, while the blisters with 100 nm diameter were created on the thin film surface. The low activation energy deduced from the Arrhenius method indicated the diffusion of hydrogen molecules.

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16

Banerjee, Rahul. "Intra-molecular Interactions in Porous Covalent Organic Frameworks." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C530. http://dx.doi.org/10.1107/s2053273314094698.

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A new strategy of intramolecular hydrogen bonding in 2D covalent organic framework as an extra stabilizing factor has been introduced, which helps to improve the crystallinity, porosity and chemical stability of the COF. Using this concept, highly stable porphyrin containing covalent organic frameworks have been synthesized using the Schiff base reaction. The stability of the COFs mainly arises due to the strong intramolecular O-H...N=C hydrogen bonding. Validation of this postulate was cross-checked by synthesizing methoxy (OCH3) substituted COF in which no hyrogen bonding exists. It was found that methoxy substituted COF have a low crystallinity, porosity and chemical stability as compared to hydrogen bonded COF.

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17

Lloyd, Gareth. "Hydrogen Bonding in Inclusion Chemistry and Porous Materials." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C533. http://dx.doi.org/10.1107/s2053273314094662.

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Hydrogen bonding played an important role in the development of crystal engineering and cocrystal formation, and continues to do so. Our take on hydrogen bonding will focus on its consequences on the functional properties of a number of materials based on how hydrogen bonding directionality effects porosity design and inclusion chemistry. The design of molecular porous materials has focused on the production of intrinsic porosity within a number of interesting materials where the intrinsic voids are defined by capsules (tetrahedra in our examples) and macrocycles (2X2 metallocycles in our examples). The crystal engineering of the macrocycle packing efficiencies can result in the intrinsic voids spaces being connected into pore networks allowing for diffusion of guest species such as gases. We will show how the hydrogen bonding of these intrinsically porous molecules can result in an increased porosity through the creation of extrinsic void space.[1] The inclusion chemistry we have investigated has looked at gas and vapour sorption where we have determined the guest:framework interaction of a number of porous materials. This includes the inclusion chemistry of a number of persistent organic radicals where the hydrogen bonding and Pi-Pi stacking interactions with the flexible host material results in paramagnetic materials whereas the pure radical materials tend towards being diamagnetic.[2] We will also describe our crystallographic insights into gas:framework interactions, especially that of the hydrogen bonding of Carbon Dioxide.[3]

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18

Feng, Ziyan, Cheng Feng, Yuntao Zhong, Zhijun Qin, Rui Mao, Lei Zhao, and Xianghua Zong. "TOC estimation of shale oil reservoir by combining nuclear magnetic resonance logging and nuclear physics logging." Journal of Geophysics and Engineering 19, no. 4 (August 2022): 833–45. http://dx.doi.org/10.1093/jge/gxac052.

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Abstract The evaluation of source rock properties has become a vital step in logging interpretation. Total organic carbon (TOC) content is the key to estimating the quality and hydrocarbon generation potential of source rocks. In the shale oilfield of the Junggar Basin, the conventional method of calculating the TOC of hydrocarbon source rocks cannot satisfy logging evaluation requirements. This paper predominantly deals with a method for the quantitative estimation of TOC in source rocks via nuclear physics and nuclear magnetic resonance (NMR) logs. According to this method, the total hydrogen index of the source rock is the sum of the response of kerogen, clay minerals and fluid, expressed by corrected neutron porosity. The hydrogen index of fluid and clay minerals is indicated by the effective porosity of NMR and the estimated clay content, respectively. To eliminate the hydrogen index of fluid, the effective NMR porosity is subtracted from the corrected neutron porosity. On this basis, a new and overlapping method suitable for clay-rich rocks and oil reservoirs is proposed. This method was developed by overlaying the scaled clay content curve on the hydrogen index curve. In non-source rocks, the two curves regularly overlap. However, in organic-rich rocks the two curves will separate. The separation distance between the two curves was used to estimate TOC continuously. Possessing sound application and benefiting from the measured results of sweet spots, this method provides new insights for TOC quantitative prediction in shale oil reservoirs.

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19

Kashkarov, Egor, Maksim Krinitcyn, Adilzhan Dyussambayev, Alexey Pirozhkov, and Maksim Koptsev. "Structure and Properties of Porous Ti3AlC2-Doped Al2O3 Composites Obtained by Slip Casting Method for Membrane Application." Materials 16, no. 4 (February 12, 2023): 1537. http://dx.doi.org/10.3390/ma16041537.

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In the present work, porous composites were fabricated from pure Al2O3 and mixed Ti3AlC2/Al2O3 powder by slip casting and sintering. The effect of sintering temperature and different composition ratio on microstructure, phase composition, porosity and gas permeation flux of the fabricated materials was investigated. The microstructure and phase composition of the samples were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The gas permeation experiments were performed using pure hydrogen at 0.1–0.9 MPa pressure. It is shown that a decrease in sintering temperature from 1500 to 1350 °C results in an increase in hydrogen permeation flux of the alumina from 5 to 25 mol/(m2 × s), which is due to higher pore size and overall porosity of the samples. Sintering of Ti3AlC2/Al2O3 powder mixtures leads to the formation of Al2O3, Al2TiO5 and TiO2 phases as a result of oxidation of the Ti3AlC2 phase, resulting in an increased pore size in the composites compared with pure alumina. The open porosity of composites increases from 3.4 to 40% with an increasing Ti3AlC2/Al2O3 ratio from 1/10 to 1/2, respectively. The composites with the highest porosity (40%) had a maximum permeation flux of 200 mol/(m2 × s). The changes in the bending strength of the alumina and composite samples, depending on the microstructure and porosity, were also discussed. The investigated composites are considered promising materials for hydrogen separation membrane supports.

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20

Kucharčík, L., M. Brůna, and A. Sládek. "Influence of Chemical Composition on Porosity in Aluminium Alloys." Archives of Foundry Engineering 14, no. 2 (June 1, 2014): 5–8. http://dx.doi.org/10.2478/afe-2014-0026.

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Abstract Porosity is one of the major defects in aluminum castings, which results is a decrease of a mechanical properties. Porosity in aluminum alloys is caused by solidification shrinkage and gas segregation. The final amount of porosity in aluminium castings is mostly influenced by several factors, as amount of hydrogen in molten aluminium alloy, cooling rate, melt temperature, mold material, or solidification interval. This article deals with effect of chemical composition on porosity in Al-Si aluminum alloys. For experiment was used Pure aluminum and four alloys: AlSi6Cu4, AlSi7Mg0, 3, AlSi9Cu1, AlSi10MgCu1.

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21

Hemme, Christina, and Wolfgang van Berk. "Hydrogeochemical Modeling to Identify Potential Risks of Underground Hydrogen Storage in Depleted Gas Fields." Applied Sciences 8, no. 11 (November 19, 2018): 2282. http://dx.doi.org/10.3390/app8112282.

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Underground hydrogen storage is a potential way to balance seasonal fluctuations in energy production from renewable energies. The risks of hydrogen storage in depleted gas fields include the conversion of hydrogen to CH4(g) and H2S(g) due to microbial activity, gas–water–rock interactions in the reservoir and cap rock, which are connected with porosity changes, and the loss of aqueous hydrogen by diffusion through the cap rock brine. These risks lead to loss of hydrogen and thus to a loss of energy. A hydrogeochemical modeling approach is developed to analyze these risks and to understand the basic hydrogeochemical mechanisms of hydrogen storage over storage times at the reservoir scale. The one-dimensional diffusive mass transport model is based on equilibrium reactions for gas–water–rock interactions and kinetic reactions for sulfate reduction and methanogenesis. The modeling code is PHREEQC (pH-REdox-EQuilibrium written in the C programming language). The parameters that influence the hydrogen loss are identified. Crucial parameters are the amount of available electron acceptors, the storage time, and the kinetic rate constants. Hydrogen storage causes a slight decrease in porosity of the reservoir rock. Loss of aqueous hydrogen by diffusion is minimal. A wide range of conditions for optimized hydrogen storage in depleted gas fields is identified.

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22

TOMII, Yoich, and Masao MIZUNO. "Hydrogen in aluminum weld and porosity (blow hole) formation." Journal of Japan Institute of Light Metals 36, no. 10 (1986): 660–72. http://dx.doi.org/10.2464/jilm.36.660.

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23

Karak, Suvendu, Sushil Kumar, Pradip Pachfule, and Rahul Banerjee. "Porosity Prediction through Hydrogen Bonding in Covalent Organic Frameworks." Journal of the American Chemical Society 140, no. 15 (March 30, 2018): 5138–45. http://dx.doi.org/10.1021/jacs.7b13558.

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24

Hou, Y., Z. Ahmed Syed, L. Jiu, J. Bai, and T. Wang. "Porosity-enhanced solar powered hydrogen generation in GaN photoelectrodes." Applied Physics Letters 111, no. 20 (November 13, 2017): 203901. http://dx.doi.org/10.1063/1.5001938.

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25

Dickenson, R. C., K. R. Lawless, and K. Wefers. "Internal lih and hydrogen porosity in solutionized AlLi alloys." Scripta Metallurgica 22, no. 6 (January 1988): 917–22. http://dx.doi.org/10.1016/s0036-9748(88)80075-9.

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26

Dispinar, D., and J. Campbell. "Porosity, hydrogen and bifilm content in Al alloy castings." Materials Science and Engineering: A 528, no. 10-11 (April 2011): 3860–65. http://dx.doi.org/10.1016/j.msea.2011.01.084.

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27

Hisaki, Ichiro, Chen Xin, Kiyonori Takahashi, and Takayoshi Nakamura. "Designing Hydrogen‐Bonded Organic Frameworks (HOFs) with Permanent Porosity." Angewandte Chemie International Edition 58, no. 33 (August 12, 2019): 11160–70. http://dx.doi.org/10.1002/anie.201902147.

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28

Hsieh, Shuchen, Hsuan-Hung Chou, Chiung-Wen Hsieh, Deng-Chyang Wu, Chao-Hung Kuo, and Feng-Huei Lin. "Hydrogen peroxide treatment of eggshell membrane to control porosity." Food Chemistry 141, no. 3 (December 2013): 2117–21. http://dx.doi.org/10.1016/j.foodchem.2013.04.115.

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29

Griffiths, W. D., and R. Raiszadeh. "Hydrogen, porosity and oxide film defects in liquid Al." Journal of Materials Science 44, no. 13 (July 2009): 3402–7. http://dx.doi.org/10.1007/s10853-009-3450-7.

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30

Finkelstein, Arkady, Arseny Schaefer, and Nikolay Dubinin. "Dehydrogenation of AlSi7Fe1 Melt during In Situ Composite Production by Oxygen Blowing." Metals 11, no. 4 (March 28, 2021): 551. http://dx.doi.org/10.3390/met11040551.

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The technology of producing a composite material in situ envisages the pre-saturation of an AlSi7Fe1 melt with hydrogen; afterwards, the melt is blown with oxygen until the hydrogen dissolved in the melt is burned out. The hydrogen content was researched during the manufacturing process of the composite material; before oxygen blowing, and at incomplete and complete burning out of the dissolved hydrogen. The interrelation between the absorbed hydrogen content and the aluminum oxide fraction was identified. A mathematical model was proposed which demonstrated that during the saturation process of the melt with oxide particles, hydrogen was absorbed on their surface as a layer close to monoatomic, which does not lead to the realization of the pores’ heterogeneous nucleation mechanism. Due to this, castings produced from the researched composite material are leakless. Incomplete burning out of hydrogen dissolved in the melt leads to the formation of significant hydrogen porosity. The proposed method of prevention of gas porosity in cast composites is an alternative to the conventional one and offers not only the purging of the melt from oxide inclusions but, on the contrary, a significant increase in their specific surface, which allows for the reduction in hydrogen content on the inclusion surface to the monoatomic level.

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31

Uludağ, M., and D. Dişpinar. "Assessment of Mechanism of Pore Formation in Directionally Solidified A356 Alloy." Archives of Foundry Engineering 17, no. 1 (March 1, 2017): 157–62. http://dx.doi.org/10.1515/afe-2017-0029.

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Abstract It is well-known that the better the control of the liquid aluminium allows obtaining of better properties. One of the most important defects that is held responsible for lower properties has been the presence of porosity. Porosity has always been associated with the amount of dissolved hydrogen in the liquid. However, it was shown that hydrogen was not the major source but only a contributor the porosity. The most important defect that causes porosity is the presence of bifilms. These defects are surface entrained mainly due to turbulence and uncontrolled melt transfer. In this work, a cylindrical mould was designed (Ø30 x 300 mm) both from sand and die. Moulds were produced both from sand and die. Water cooled copper chill was placed at the bottom of the mould in order to generate a directional solidification. After the melt was prepared, prior to casting of the DC cast samples, reduced pressure test sample was taken to measure the melt quality (i.e. bifilm index). The cast parts were then sectioned into regions and longitudinal and transverse areas were investigated metallographically. Pore size, shape and distribution was measured by image analysis. The formation of porosity was evaluated by means of bifilm content, size and distribution in A356 alloy.

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Liang, Yuan-Chang, Chen-Shiang Hung, and Wei-Cheng Zhao. "Thermal Annealing Induced Controllable Porosity and Photoactive Performance of 2D ZnO Sheets." Nanomaterials 10, no. 7 (July 11, 2020): 1352. http://dx.doi.org/10.3390/nano10071352.

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Porous ZnO sheets containing various degrees of a nanoscaled pore were successfully synthesized using a simple hydrothermal method and various postannealing procedures. The porosity features of the ZnO sheets can be easily tuned by changing both the annealing temperature and annealing atmosphere. The dense porous nature of ZnO sheets is beneficial to enhance light absorption. Moreover, the substantially increased oxygen vacancies in the ZnO sheets were observed especially after the hydrogen treatment as revealed in the X-ray photoelectron spectroscope and photoluminescence analyses. The high density of surface crystal defect enhanced the photoinduced electron-hole separation rate of the ZnO sheets, which is crucial for an improved photoactivity. The porous ZnO sheets formed at a hydrogen atmosphere exhibited superior photoactive performance than the porous ZnO sheets formed at the high-temperature ambient air annealing. The dense pores and massive crystal defects formed by a hydrogen atmosphere annealing in the ZnO crystals might account for the observed photoactive behaviors in this study.

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Liu, Jun, Xiang Mei Meng, and Hong Tao Mu. "Study on the Physical and Mechanical Performance of Graphite Foamed Cement-Based Material." Advanced Materials Research 1089 (January 2015): 265–69. http://dx.doi.org/10.4028/www.scientific.net/amr.1089.265.

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To figure out the physical and mechanical performance of graphite foam concrete，orthogonal test was applied to ascertain four factors for graphite foamed cement-based material (GFCBM). The influence of water cement ratio, graphite content, hydrogen peroxide content and sodium sulfite content on the dry density, porosity and compressive strength was also discussed. The results show that sodium sulfite has a relatively significant effect on the physical and mechanical performance. The dry density and compressive strength increases first and then decrease with the water cement ratio, adding of hydrogen peroxide and sodium sulfite increasing and increase with adding of the graphite. The trend of porosity is opposite to the dry density and compressive strength. The optimal scheme for this experiment is water cement ratio 0.68, 5% graphite, 8% hydrogen peroxide and 6% sodium sulfate.

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34

Gnedovets, A. G., V. A. Zelenskii, V. S. Shustov, and M. I. Alymov. "REDOX NANOSTRUCTURING OF BIPOROUS NICKEL (II) SINTERED USING A SPACE HOLDER." Доклады Российской академии наук. Химия, науки о материалах 511, no. 1 (July 1, 2023): 47–53. http://dx.doi.org/10.31857/s2686953522600568.

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Permeable metallic nickel and ceramic nickel-oxide materials with nanostructured surface and multilevel hierarchical porosity were created by cyclic redox post-treatment of biporous nickel (II) consolidated in the sintering-dissolution process. Additional levels of intraparticle porosity – Kirkendall pores and shrinkage nanopores – were formed during the stages of high-temperature oxidation in air and reduction in hydrogen, respectively.

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35

Gong, Myungkeun, Changhyun Jin, and Youngseung Na. "Minimizing Area-Specific Resistance of Electrochemical Hydrogen Compressor under Various Operating Conditions Using Unsteady 3D Single-Channel Model." Membranes 13, no. 6 (May 26, 2023): 555. http://dx.doi.org/10.3390/membranes13060555.

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Extensive research has been conducted over the past few decades on carbon-free hydrogen energy. Hydrogen, being an abundant energy source, requires high-pressure compression for storage and transportation due to its low volumetric density. Mechanical and electrochemical compression are two common methods used to compress hydrogen under high pressure. Mechanical compressors can potentially cause contamination due to the lubricating oil when compressing hydrogen, whereas electrochemical hydrogen compressors (EHCs) can produce high-purity, high-pressure hydrogen without any moving parts. A study was conducted using a 3D single-channel EHC model focusing on the water content and area-specific resistance of the membrane under various temperature, relative humidity, and gas diffusion layer (GDL) porosity conditions. Numerical analysis demonstrated that the higher the operating temperature, the higher the water content in the membrane. This is because the saturation vapor pressure increases with higher temperatures. When dry hydrogen is supplied to a sufficiently humidified membrane, the actual water vapor pressure decreases, leading to an increase in the membrane’s area-specific resistance. Furthermore, with a low GDL porosity, the viscous resistance increases, hindering the smooth supply of humidified hydrogen to the membrane. Through a transient analysis of an EHC, favorable operating conditions for rapidly hydrating membranes were identified.

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Akanji, Olaitan L., and Andrei V. Kolesnikov. "Modeling of heat and mass transfer in LaNi5 matrix during hydrogen absorption-desorption cycle." Polish Journal of Chemical Technology 14, no. 3 (October 1, 2012): 71–76. http://dx.doi.org/10.2478/v10026-012-0087-0.

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Packed bed reactors using metal hydride are attracting a lot of attention as potential hydrogen storage systems. Some operational and design variables are major constraints to obtain a proper infl ow/outfl ow of hydrogen into a metal hydride reactor. These variables include packed bed thermal conductivity, porosity, pressure and temperature distributions in the reactor during the absorption/desorption cycle. They also cause a mechanical stress induced by temperature gradient. In this paper, two dimensional models are implemented in COMSOL multiphysics to simulate the hydrogen fl ow, pressure and temperature distributions in the packed bed reactor during absorption/desorption cycle. Also, stresses in porous metal hydride induced by temperature variation in the heating/cooling cycle were evaluated. A possible effect of stress induced, porosity changes on diffusion and heating of hydrogen in both radial and axial direction in packed bed is discussed. The model consists of a system of partial differential equations (PDE) describing structural mechanics of stress, heat and mass transfer of hydrogen in the porous matrix of the packed bed reactor.

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Zentner, Cassandra A., Holden W. H. Lai, Joshua T. Greenfield, Ren A. Wiscons, Matthias Zeller, Charles F. Campana, Orhan Talu, Stephen A. FitzGerald, and Jesse L. C. Rowsell. "High surface area and Z′ in a thermally stable 8-fold polycatenated hydrogen-bonded framework." Chemical Communications 51, no. 58 (2015): 11642–45. http://dx.doi.org/10.1039/c5cc04219d.

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Gaviphatt, Natnapat, Prabhas Chongstitvatana, and Chedtha Puncreobutr. "Application of Evolution Algorithms to Aluminium Alloy Casting Porosity Prediction Function." Applied Mechanics and Materials 799-800 (October 2015): 372–76. http://dx.doi.org/10.4028/www.scientific.net/amm.799-800.372.

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Porosity is a major problem occurring in aluminium alloy casting. During the process of solidification, alloy would shrink and emit dissolving hydrogen causing porosity formation inside the solidified part which leads to mechanical properties degradation. This research aims to produce a formula to explain the resulting porosity with the initial chemical compositions and cooling rate. A mathematic model is, at first, inferred from previous researches to be a template function. Differential Evolution is utilized to generate inner polynomial parts and to find appropriate coefficients to experimental data obtained from other publications. The optimized function promisingly shows good fit to the problem domain demonstrating that the resulting function is an efficient model to explain porosity formation behaviour.

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Moles, Rémi, Annabelle Laplace, Jean-Gabriel Begos, Charlène Vallat, Elise Regnier, Lilou Schintu, Alexandre Sierk, and Karl Vulliez. "Study of a Glass-Ceramic Seal Porosity." ECS Transactions 111, no. 6 (May 19, 2023): 2377–83. http://dx.doi.org/10.1149/11106.2377ecst.

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Sealing is a major issue in Solid Oxide Cell (SOC) used for hydrogen production. Currently, a slurry composed of glass powder, organic solvents and adjuvants, is used as a seal. After the deposition of the slurry on the areas to be sealed, a heat treatment allows to obtain a glass-ceramic. This shaping process is very convenient but the obtained material presents porosity. This study aims to understand the evolution of porosity as a function of time and temperature in order to minimize it. A significant increase in porosity is observed when the temperature increases. The porosity evolution is characterized by an increase in pores size and a reduction of pores number, typical of a coalescence phenomenon. At high temperature, the viscosity is low enough to allow pores to rise in the sample. This weakens the upper part of the seal and may cause a loss of sealing.

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Kao, Wei Xin, Tai Nan Lin, Yang Chuang Chang, and Maw Chwain Lee. "Oscillation Phenomenon of the Cell Performance for an Anode-Supported Solid Oxide Fuel Cell with a Low-Porosity/High-Thickness Anode Structure." Key Engineering Materials 656-657 (July 2015): 124–28. http://dx.doi.org/10.4028/www.scientific.net/kem.656-657.124.

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The anode-supported solid oxide fuel cell (SOFC) with low-porosity anode structure is fabricated and the electrochemical characteristics are investigated. The electrochemical characterization of the cell shows a periodic oscillation phenomenon of the cell voltage under the constant current density operation. The low-porosity anode structure results in the decrease in the effective diffusion coefficient and the accumulation of water vapor. The cell voltage oscillation is mainly caused by the concentration polarization as well as the boundary migration of the reaction zone. The profound influence on the concentration polarization can be observed when the cell test is executed with operation condition of higher current density, lower hydrogen concentration, and lower hydrogen flow rate in the anode side.

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Kunowsky, Mirko, Juan Pablo Marco-Lozar, and Ángel Linares-Solano. "Activated Carbon Fibre Monoliths for Hydrogen Storage." Advances in Science and Technology 93 (October 2014): 102–11. http://dx.doi.org/10.4028/www.scientific.net/ast.93.102.

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Porous adsorbents are currently investigated for hydrogen storage application. From a practical point of view, in addition to high porosity developments, high material densities are required, in order to confine as much material as possible in a tank device. In this study, we use different measured sample densities (tap, packing, compacted and monolith) for analyzing the hydrogen adsorption behavior of activated carbon fibres (ACFs) and activated carbon nanofibres (ACNFs) which were prepared by KOH and CO2 activations, respectively. Hydrogen adsorption isotherms are measured for all of the adsorbents at room temperature and under high pressures (up to 20 MPa). The obtained results confirm that (i) gravimetric H2 adsorption is directly related to the porosity of the adsorbent, (ii) volumetric H2 adsorption depends on the adsorbent porosity and importantly also on the material density, (iii) the density of the adsorbent can be improved by packing the original adsorbents under mechanical pressure or synthesizing monoliths from them, (iv) both ways (packing under pressure or preparing monoliths) considerably improve the storage capacity of the starting adsorbents, and (v) the preparation of monoliths, in addition to avoid engineering constrains of packing under mechanical pressure, has the advantage of providing high mechanical resistance and easy handling of the adsorbent.

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42

Ueno, Shunkichi, Li Ming Lin, and Hideo Nakajima. "Effect of Impurities on Formation of Pores in Porous Alumina during Unidirectional Solidification." Materials Science Forum 569 (January 2008): 313–16. http://dx.doi.org/10.4028/www.scientific.net/msf.569.313.

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A porous alumina with cylindrical pores was fabricated by unidirectional solidification under hydrogen gas flow (0.1 MPa) using alumina feed rods doped with silica, calcia or sodium oxide. The additives in the feed rods strongly affect the formation of porous structure during the solidification. The porosity increases with increasing silica content. The increase of porosity is enhanced by further addition of sodium oxide. The addition of calcia to the feed rod is effective on the homogenization of pore distribution. The porous alumina with 1mol%CaO and 20mol%SiO2 additives showed 50% porosity and homogeneous pores distribution.

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43

Kljajevic, Ljiljana, Vladislava Jovanovic, Sanja Stevanovic, Zarko Bogdanov, and Branka Kaludjerovic. "Influence of chemical agents on the surface area and porosity of active carbon hollow fibers." Journal of the Serbian Chemical Society 76, no. 9 (2011): 1283–94. http://dx.doi.org/10.2298/jsc100226112k.

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Active carbon hollow fibers were prepared from regenerated polysulfone hollow fibers by chemical activation using: disodium hydrogen phosphate 2-hydrate, disodium tetraborate 10-hydrate, hydrogen peroxide, and diammonium hydrogen phosphate. After chemical activation fibers were carbonized in an inert atmosphere. The specific surface area and porosity of obtained carbons were studied by nitrogen adsorption-desorption isotherms at 77 K, while the structures were examined with scanning electron microscopy and X-ray diffraction. The activation process increases these adsorption properties of fibers being more pronounced for active carbon fibers obtained with disodium tetraborate 10-hydrate and hydrogen peroxide as activator. The obtained active hollow carbons are microporous with different pore size distribution. Chemical activation with phosphates produces active carbon material with small surface area with but with both mesopores and micropores. X-ray diffraction shows that besides turbostratic structure typical for carbon materials, there are some peaks which indicate some intermediate reaction products when sodium salts were used as activating agent. Based on data from the electrochemical measurements the activity and porosity of the active fibers depend strongly on the oxidizing agent applied.

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44

Wang, Bin, Xiu-Liang Lv, Jie Lv, Li Ma, Rui-Biao Lin, Hui Cui, Jian Zhang, Zhangjing Zhang, Shengchang Xiang, and Banglin Chen. "A novel mesoporous hydrogen-bonded organic framework with high porosity and stability." Chemical Communications 56, no. 1 (2020): 66–69. http://dx.doi.org/10.1039/c9cc07802a.

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45

Zhou, Haiqing, Fang Yu, Yuanyue Liu, Jingying Sun, Zhuan Zhu, Ran He, Jiming Bao, William A. Goddard, Shuo Chen, and Zhifeng Ren. "Outstanding hydrogen evolution reaction catalyzed by porous nickel diselenide electrocatalysts." Energy & Environmental Science 10, no. 6 (2017): 1487–92. http://dx.doi.org/10.1039/c7ee00802c.

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46

Kuebel, C., A. Roth, D. Wang, Z. Zhao-Karger, and M. Fichtner. "Porosity and Wetting Behavior in Model Systems for Hydrogen Storage." Microscopy and Microanalysis 16, S2 (July 2010): 1666–67. http://dx.doi.org/10.1017/s1431927610058964.

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47

Lee, P. D., and J. D. Hunt. "Hydrogen porosity in directional solidified aluminium-copper alloys:in situ observation." Acta Materialia 45, no. 10 (October 1997): 4155–69. http://dx.doi.org/10.1016/s1359-6454(97)00081-5.

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48

Hisaki, Ichiro, Xin Chen, Kiyonori Takahashi, and Takayoshi Nakamura. "Corrigendum: Designing Hydrogen‐Bonded Organic Frameworks (HOFs) with Permanent Porosity." Angewandte Chemie International Edition 58, no. 42 (October 7, 2019): 14794. http://dx.doi.org/10.1002/anie.201909732.

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Hirscher, Michael. "Hydrogen Storage by Cryoadsorption in Ultrahigh-Porosity Metal-Organic Frameworks." Angewandte Chemie International Edition 50, no. 3 (December 29, 2010): 581–82. http://dx.doi.org/10.1002/anie.201006913.

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Hisaki, Ichiro, Xin Chen, Kiyonori Takahashi, and Takayoshi Nakamura. "Berichtigung: Designing Hydrogen‐Bonded Organic Frameworks (HOFs) with Permanent Porosity." Angewandte Chemie 131, no. 42 (October 7, 2019): 14938. http://dx.doi.org/10.1002/ange.201909732.

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