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7 pages, 10330 KiB  
Proceeding Paper
Evaluation of the Corrosion Behavior of Low-Temperature Nitrided AISI 316L Austenitic Stainless Steel
by Francesca Borgioli
Eng. Proc. 2025, 105(1), 1; https://doi.org/10.3390/engproc2025105001 - 1 Aug 2025
Viewed by 75
Abstract
Nitriding of austenitic stainless steels at low temperatures hinders the precipitation of chromium nitrides and causes the formation of a supersaturated solid solution of nitrogen atoms in the austenite lattice, known as expanded austenite. In this study, the corrosion behavior of low-temperature nitrided [...] Read more.
Nitriding of austenitic stainless steels at low temperatures hinders the precipitation of chromium nitrides and causes the formation of a supersaturated solid solution of nitrogen atoms in the austenite lattice, known as expanded austenite. In this study, the corrosion behavior of low-temperature nitrided AISI 316L is investigated in a NaCl solution using different electrochemical techniques, electrochemical impedance spectroscopy, cyclic potentiodynamic polarization and galvanostatic tests, in order to assess the effect of test conditions. The nitrided layer has an enhanced resistance to localized corrosion, but its ability to repassivate depends on the damage extent caused by the different tests. Full article
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19 pages, 3737 KiB  
Article
Short-Term Morphological Response of Polypropylene Membranes to Hypersaline Lithium Fluoride Solutions: A Multiscale Modeling Approach
by Giuseppe Prenesti, Pierfrancesco Perri, Alessia Anoja, Agostino Lauria, Carmen Rizzuto, Alfredo Cassano, Elena Tocci and Alessio Caravella
Int. J. Mol. Sci. 2025, 26(15), 7380; https://doi.org/10.3390/ijms26157380 - 30 Jul 2025
Viewed by 195
Abstract
Understanding the early-stage physical interactions between polymeric membranes and supersaturated salt solutions is crucial for advancing membrane-assisted crystallization (MCr) processes. In this study, we employed molecular dynamics (MD) simulations to investigate the short-term morphological response of an isotactic polypropylene (PP) membrane in contact [...] Read more.
Understanding the early-stage physical interactions between polymeric membranes and supersaturated salt solutions is crucial for advancing membrane-assisted crystallization (MCr) processes. In this study, we employed molecular dynamics (MD) simulations to investigate the short-term morphological response of an isotactic polypropylene (PP) membrane in contact with LiF solutions at different concentrations (5.8 M and 8.9 M) and temperatures (300–353 K), across multiple time points (0, 150, and 300 ns). These data were used as input for computational fluid dynamics (CFD) analysis to evaluate structural descriptors of the membrane, including tortuosity, connectivity, void fraction, anisotropy, and deviatoric anisotropy, under varying thermodynamic conditions. The results show subtle but consistent rearrangements of polymer chains upon exposure to the hypersaline environment, with a marked reduction in anisotropy and connectivity, indicating a more compact and isotropic local structure. Surface charge density analyses further suggest a temperature- and concentration-dependent modulation of chain mobility and terminal group orientation at the membrane–solution interface. Despite localized rearrangements, the membrane consistently maintains a net negative surface charge. This electrostatic feature may influence ion–membrane interactions during the crystallization process. While these non-reactive, short-timescale simulations do not capture long-term degradation or fouling mechanisms, they provide mechanistic insight into the initial physical response of PP membranes under MCr-relevant conditions. This study lays a computational foundation for future investigations bridging atomistic modeling and membrane performance in real-world applications. Full article
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25 pages, 14812 KiB  
Article
The Effect of Yttrium Addition on the Solidification Microstructure and Sigma Phase Precipitation Behavior of S32654 Super Austenitic Stainless Steel
by Jun Xiao, Geng Tian, Di Wang, Shaoguang Yang, Kuo Cao, Jianhua Wei and Aimin Zhao
Metals 2025, 15(7), 798; https://doi.org/10.3390/met15070798 - 15 Jul 2025
Viewed by 262
Abstract
This study focuses on S32654 super austenitic stainless steel (SASS) and systematically characterizes the morphology of the sigma (σ) phase and the segregation behavior of alloying elements in its as-cast microstructure. High-temperature confocal scanning laser microscopy (HT-CSLM) was employed to investigate the effect [...] Read more.
This study focuses on S32654 super austenitic stainless steel (SASS) and systematically characterizes the morphology of the sigma (σ) phase and the segregation behavior of alloying elements in its as-cast microstructure. High-temperature confocal scanning laser microscopy (HT-CSLM) was employed to investigate the effect of the rare earth element yttrium (Y) on the solidification microstructure and σ phase precipitation behavior of SASS. The results show that the microstructure of SASS consists of austenite dendrites and interdendritic eutectoid structures. The eutectoid structures mainly comprise the σ phase and the γ2 phase, exhibiting lamellar or honeycomb-like morphologies. Regarding elemental distribution, molybdenum displays a “concave” distribution pattern within the dendrites, with lower concentrations at the center and higher concentrations at the sides; when Mo locally exceeds beyond a certain threshold, it easily induces the formation of eutectoid structures. Mo is the most significant segregating element, with a segregation ratio as high as 1.69. The formation mechanism of the σ phase is attributed to the solid-state phase transformation of austenite (γ → γ2 + σ). In the late stages of solidification, the concentration of chromium and Mo in the residual liquid phase increases, and due to insufficient diffusion, there are significant compositional differences between the interdendritic regions and the matrix. The enriched Cr and Mo cause the interdendritic austenite to become supersaturated, leading to solid-state phase transformation during subsequent cooling, thereby promoting σ phase precipitation. The overall phase transformation process can be summarized as L → L + γ → γ → γ + γ2 + σ. Y microalloying has a significant influence on the solidification process. The addition of Y increases the nucleation temperature of austenite, raises nucleation density, and refines the solidification microstructure. However, Y addition also leads to an increased amount of eutectoid structures. This is primarily because Y broadens the solidification temperature range of the alloy and prolongs grain growth perio, which aggravates the microsegregation of elements such as Cr and Mo. Moreover, Y raises the initial precipitation temperature of the σ phase and enhances atomic diffusion during solidification, further promoting σ phase precipitation during the subsequent eutectoid transformation. Full article
(This article belongs to the Special Issue Synthesis, Processing and Applications of New Forms of Metals)
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9 pages, 859 KiB  
Article
The Impact of Arginine Side Chains on the Mechanism of Polycondensation of Silicic Acid in Bioinspired Mineralization
by Jose Lanuza and Enrico Ravera
Inorganics 2025, 13(6), 206; https://doi.org/10.3390/inorganics13060206 - 19 Jun 2025
Viewed by 384
Abstract
The polycondensation of silica from soluble silicic acid is at the basis of several chemical processes. The usual industrial route requires harsh pH conditions and high concentrations of the precursor molecules, not to mention a thermal treatment for obtaining condensed structures. On the [...] Read more.
The polycondensation of silica from soluble silicic acid is at the basis of several chemical processes. The usual industrial route requires harsh pH conditions and high concentrations of the precursor molecules, not to mention a thermal treatment for obtaining condensed structures. On the other hand, biological organisms can promote the precipitation of silica under physiological conditions, including temperature and pH, and low concentrations of precursors. The key to this process is the use of polycationic molecules. Despite the relevance of these processes in modern industrial inorganic chemistry, this fascinating process is still not completely understood. Recent studies converge in pointing out that the role of the polycation is to create supersaturation of silicic acid in its immediate proximity, which would explain the impact of the polycation on the reaction rates. However, it remains unclear whether these polycations also directly influence the reaction mechanism at a molecular level. In this manuscript, we address this question by analyzing the reaction pathway of silicic acid dimerization in the presence of guanidinium as a mimic of the arginine side chain, through DFT calculations. We found that the impact on the reaction pathway is minimal, which strengthens the hypothesis of the local supersaturation driven by the polycationic molecules. Full article
(This article belongs to the Special Issue State-of-the-Art Inorganic Chemistry in Italy)
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17 pages, 2713 KiB  
Article
Mineral Deposition on the Rough Walls of a Fracture
by Nathann Teixeira Rodrigues, Ismael S. S. Carrasco, Vaughan R. Voller and Fábio D. A. Aarão Reis
Minerals 2024, 14(12), 1213; https://doi.org/10.3390/min14121213 - 28 Nov 2024
Viewed by 836
Abstract
Modeling carbonate growth in fractures and pores is important for understanding carbon sequestration in the environment or when supersaturated solutions are injected into rocks. Here, we study the simple but nontrivial problem of calcite growth on fractures with rough walls of the same [...] Read more.
Modeling carbonate growth in fractures and pores is important for understanding carbon sequestration in the environment or when supersaturated solutions are injected into rocks. Here, we study the simple but nontrivial problem of calcite growth on fractures with rough walls of the same mineral using kinetic Monte Carlo simulations of attachment and detachment of molecules and scaling approaches. First, we consider wedge-shaped fracture walls whose upper terraces are in the same low-energy planes and show that the valleys are slowly filled by the propagation of parallel monolayer steps in the wedge sides. The growth ceases when the walls reach these low-energy configurations so that a gap between the walls may not be filled. Second, we consider fracture walls with equally separated monolayer steps (vicinal surfaces with roughness below 1 nm) and show that growth by step propagation will eventually clog the fracture gap. In both cases, scaling approaches predict the times to attain the final configurations as a function of the initial geometry and the step-propagation velocity, which is set by the saturation index. The same reasoning applied to a random wall geometry shows that step propagation leads to lateral filling of surface valleys until the wall reaches the low-energy crystalline plane that has the smallest initial density of molecules. Thus, the final configurations of the fracture walls are much more sensitive to the crystallography than to the roughness or the local curvature. The framework developed here may be used to determine those configurations, the times to reach them, and the mass of deposited mineral. Effects of transport limitations are discussed when the fracture gap is significantly narrowed. Full article
(This article belongs to the Special Issue Mineral Dissolution and Precipitation in Geologic Porous Media)
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19 pages, 13789 KiB  
Article
Self-Organization of Micro- and Nanosystems in the Form of Patterns
by Vyacheslav Perekrestov, Anna Kornyushchenko, Yuliia Kosminska, Maksym Kubakh and Gerhard Wilde
Crystals 2024, 14(11), 953; https://doi.org/10.3390/cryst14110953 - 31 Oct 2024
Cited by 1 | Viewed by 830
Abstract
In this work, the peculiarities of self-organization of patterned micro- and nanosystems under near-equilibrium condensation conditions were consistently considered. The criteria for stationarity of near-equilibrium condensation were introduced, and interrelations between the condensate local growth kinetics and the corresponding local technological parameters were [...] Read more.
In this work, the peculiarities of self-organization of patterned micro- and nanosystems under near-equilibrium condensation conditions were consistently considered. The criteria for stationarity of near-equilibrium condensation were introduced, and interrelations between the condensate local growth kinetics and the corresponding local technological parameters were described. Dissipative self-organization of small supersaturations in physically and chemically active medium-condensate systems were compared. The effectiveness of the unification of dissipative self-organization of small supersaturations and conservative self-organization of patterned micro- and nanosystems formation was shown, which forms the basis of a new concept of complete self-organized systems. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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12 pages, 4097 KiB  
Article
The Effect of Template Reset Operation on the Number of Crystals Precipitated at the Air–Solution Template Interface
by Bolor-Uyanga Tumurbaatar, Shuntaro Amari and Hiroshi Takiyama
Crystals 2024, 14(7), 591; https://doi.org/10.3390/cryst14070591 - 27 Jun 2024
Viewed by 1634
Abstract
The application of template crystallization to developing novel crystalline materials has attracted attention. However, when the air–solution interface becomes the template interface and the target material crystallizes, new nucleation at the template interface is prevented, which is predicted to prevent the increase in [...] Read more.
The application of template crystallization to developing novel crystalline materials has attracted attention. However, when the air–solution interface becomes the template interface and the target material crystallizes, new nucleation at the template interface is prevented, which is predicted to prevent the increase in the total number of crystals. In this study, we investigated the effect of operations that change the driving force at the air–solution template interface on the number of crystals at the interface. The number of crystals precipitated by changing the local supersaturation was investigated by a novel “template reset” operation, in which the concentration driving force near the template interface is changed by dissolving the crystals at the interface, once precipitated. The results showed that the number of crystals increased significantly after the template reset operation, and the particle size distribution was also improved. The temperature of the solution near the interface after the template reset operation was higher than that of the solution at the bottom of the petri dish and the prepared saturated solution, suggesting that the driving force of crystallization was higher. Full article
(This article belongs to the Section Industrial Crystallization)
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17 pages, 2776 KiB  
Article
Homogeneous Organic Crystal Nucleation Rates in Solution from the Perspective of Chemical Reaction Kinetics
by Sven L. M. Schroeder
Crystals 2024, 14(4), 349; https://doi.org/10.3390/cryst14040349 - 6 Apr 2024
Cited by 4 | Viewed by 2266
Abstract
It is demonstrated for 11 different combinations of organic solutes and solvents that the supersaturation dependence of homogeneous organic crystal nucleation rates from solution can be predicted from the solubility, bar a single empirical rate constant, when it is assumed that nucleation takes [...] Read more.
It is demonstrated for 11 different combinations of organic solutes and solvents that the supersaturation dependence of homogeneous organic crystal nucleation rates from solution can be predicted from the solubility, bar a single empirical rate constant, when it is assumed that nucleation takes place in reversible aggregates of solvated solutes formed in supersaturated solutions. Reversible solute aggregation represents natural solute density fluctuations that take place in any solute/solvent system. For thermodynamically ideal solutions, the steady state size distribution, and thus the population of reversible aggregates in supersaturated solution, can be predicted quantitatively from the overall solute concentration by a simple mathematical expression. Supersaturation creates an excess of reversible aggregates with sizes exceeding that of the largest aggregate in saturated solution. It is shown that the number of these excess aggregates is proportional to experimental homogeneous nucleation rates, suggesting a rate equation for homogeneous nucleation that has only one empirical parameter, namely, a rate constant specific to the solute/solvent combination. This rate constant can be determined from standard nucleation rate data. The system-specificity of homogeneous nucleation rates thus appears to be encoded solely in a rate constant for the transformation of the large excess aggregates into crystal nuclei. The driving force for triggering nucleation events in these aggregates is likely the extremely high local supersaturation, which provides the conditions for spatiotemporally aligned bond-breaking (e.g., de-solvation) and bond-forming (e.g., solute–solute bonding) events that create stable crystal nuclei. The possible influence of heterogeneous nucleation by solid impurities is considered. Full article
(This article belongs to the Special Issue Feature Papers in Crystals 2023)
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21 pages, 5827 KiB  
Article
Nafion: A Flexible Template for Selective Structuring
by Nikolai F. Bunkin, Polina N. Bolotskova, Sergey V. Gudkov, Minh T. Khuong, Valeriy A. Kozlov, Svetlana L. Timchenko, Valeriy V. Voronov and Yulia V. Novakovskaya
Polymers 2024, 16(6), 744; https://doi.org/10.3390/polym16060744 - 8 Mar 2024
Cited by 3 | Viewed by 1452
Abstract
The peculiarities of crystal growth on a Nafion polymeric substrate from supersaturated aqueous solutions of initial substances were studied. The solutions were prepared based on deionized natural water and deuterium-depleted water. As was found earlier, in natural water (deuterium content 157 ± 1 [...] Read more.
The peculiarities of crystal growth on a Nafion polymeric substrate from supersaturated aqueous solutions of initial substances were studied. The solutions were prepared based on deionized natural water and deuterium-depleted water. As was found earlier, in natural water (deuterium content 157 ± 1 ppm) polymer fibers are capable of unwinding towards the bulk of the liquid, while in deuterium-depleted water (deuterium content ≤ 3 ppm) there is no such effect. Since the distance between the unwound fibers falls in a nanometer range (which is close to the size of the unit cell of the crystal lattice), and these fibers are directed normally to the polymeric substrate, the unwinding can affect crystal growth on the polymer substrate. As was obtained in experiments with X-ray diffractometry, the unwound polymer fibers predetermine syngony of crystals, for which the unit cell is either a rectangular parallelepiped (monoclinic system) or an oblique parallelepiped (triclinic system). A quantitative theoretical model that describes the local interaction of the polymer substrate with the crystalline complexes is presented. Within this model, the polymer substrate can be considered as a flexible matrix for growing crystals. Full article
(This article belongs to the Special Issue Status and Progress of Soluble Polymers II)
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15 pages, 2692 KiB  
Article
Prediction of the Secondary Arms Spacing Based on Dendrite Tip Kinetics and Cooling Rate
by Ibrahim Sari, Mahmoud Ahmadein, Sabbah Ataya, Lakhdar Hachani, Kader Zaidat, Nashmi Alrasheedi, Menghuai Wu and Abdellah Kharicha
Materials 2024, 17(4), 865; https://doi.org/10.3390/ma17040865 - 13 Feb 2024
Cited by 4 | Viewed by 2909
Abstract
Secondary dendrite arm spacing (SDAS) is one of the most important factors affecting macrosegregation and mechanical properties in solidification processes. Predicting SDAS is one of the major parameters in foundry technology. In order to predict the evolution of microstructures during the solidification process, [...] Read more.
Secondary dendrite arm spacing (SDAS) is one of the most important factors affecting macrosegregation and mechanical properties in solidification processes. Predicting SDAS is one of the major parameters in foundry technology. In order to predict the evolution of microstructures during the solidification process, we proposed a simple model which predicted the secondary dendrite arm spacing based solely on the tip velocity (related to the tip supersaturation) and cooling rate. The model consisted of a growing cylinder inside a liquid cylindrical envelope. Two important hypotheses were made: (1) Initially the cylinder radius was assumed to equal the dendrite tip radius and (2) the cylindrical envelope had a fixed radius in the order of the dendrite tip diffusion length. The numerical model was tested against experiments using various Pb–Sn alloys for a fixed temperature gradient. The results were found to be in excellent agreement with experimental measurements in terms of SDAS and dendrite tip velocity prediction. This simple model is naturally destined to be implemented as a sub-grid model in volume-averaging models to predict the local microstructure, which in turn directly controls the mushy zone permeability and macrosegregation phenomena. Full article
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14 pages, 4232 KiB  
Article
Microstructure Evolution during High-Pressure Torsion in a 7xxx AlZnMgZr Alloy
by Anwar Qasim Ahmed, Dániel Olasz, Elena V. Bobruk, Ruslan Z. Valiev and Nguyen Q. Chinh
Materials 2024, 17(3), 585; https://doi.org/10.3390/ma17030585 - 25 Jan 2024
Viewed by 1333
Abstract
A homogenized, supersaturated AlZnMgZr alloy was processed via severe plastic deformation (SPD) using a high-pressure torsion (HPT) technique for different revolutions at room temperature to obtain an ultrafine-grained (UFG) microstructure. The microstructure and mechanical properties of the UFG samples were then studied using [...] Read more.
A homogenized, supersaturated AlZnMgZr alloy was processed via severe plastic deformation (SPD) using a high-pressure torsion (HPT) technique for different revolutions at room temperature to obtain an ultrafine-grained (UFG) microstructure. The microstructure and mechanical properties of the UFG samples were then studied using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and tensile and hardness measurements. The main purpose was to study the effect of shear strain on the evolution of the microstructure of the investigated alloy. We found a very interesting evolution of the decomposed microstructure in a wide range of shear strains imposed by HPT. While the global properties, such as the average grain size (~200 nm) and hardness (~2200 MPa) appeared unchanged, the local microstructure was continuously transformed. After 1 turn of HPT, the decomposed UFG structure contained relatively large precipitates inside grains. In the sample processed by five turns in HPT, the segregation of Zn atoms into grain boundaries (GBs) was also observed. After 10 turns, more Zn atoms were segregated into GBs and only smaller-sized precipitates were observed inside grains. The intensive solute segregations into GBs may significantly affect the ductility of the material, leading to its ultralow-temperature superplasticity. Our findings pave the way for achieving advanced microstructural and mechanical properties in nanostructured metals and alloys by engineering their precipitation and segregation by means of applying different HPT regimes. Full article
(This article belongs to the Special Issue Plastic Deformation and Mechanical Behavior of Metallic Materials)
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24 pages, 7446 KiB  
Article
Controlling Crystal Growth of a Rare Earth Element Scandium Salt in Antisolvent Crystallization
by Josia Tonn, Andreas Roman Fuchs, Leon Libuda and Andreas Jupke
Crystals 2024, 14(1), 94; https://doi.org/10.3390/cryst14010094 - 19 Jan 2024
Cited by 2 | Viewed by 2174
Abstract
Recovering scandium from hydrometallurgical residue bears the potential of a better supply of an industry depending on imports from countries with more mineral resources than Europe. To recover scandium from unused metal production residue, strip liquors from a solvent extraction process are treated [...] Read more.
Recovering scandium from hydrometallurgical residue bears the potential of a better supply of an industry depending on imports from countries with more mineral resources than Europe. To recover scandium from unused metal production residue, strip liquors from a solvent extraction process are treated with an antisolvent to crystallize the ammonium scandium fluoride salt (NH4)3ScF6 with high product yields. However, high local supersaturation leads to strong nucleation, resulting in small crystals, which are difficult to handle in the subsequent solid-liquid separation. Reducing local supersaturation makes it possible to reduce nucleation and control crystal growth. Key operation parameters are the concentration of ethanol in the feed and its addition rate. The concentration of the antisolvent in the feed causes a shorter mixing time in the proximity of the antisolvent inlet, which leads to a smaller local supersaturation and therefore less nucleation and more crystal growth. Lowering the antisolvent addition rate enhances this effect. The crystal size distribution during and at the end of the fed-batch process is analyzed by SEM imagery of sampled and dried crystals. To produce reproducible crystal size distribution from SEM images the neural network Mask R-CNN has been trained for the automated crystal detection and size analysis. Full article
(This article belongs to the Special Issue Crystallization Process and Simulation Calculation, Second Edition)
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17 pages, 4674 KiB  
Article
Tyrosine Amino Acid as a Foulant for the Heterogeneous Anion Exchange Membrane
by Anastasiia Kharina and Tatiana Eliseeva
Membranes 2023, 13(10), 844; https://doi.org/10.3390/membranes13100844 - 22 Oct 2023
Cited by 2 | Viewed by 2433
Abstract
The features of organic fouling have been revealed for highly basic anion exchange membranes during prolonged electrodialysis in solutions containing the aromatic amino acid tyrosine. With increased operation time when using MA-41 heterogeneous membranes in tyrosine solution, an increase in hydrophobicity and roughness [...] Read more.
The features of organic fouling have been revealed for highly basic anion exchange membranes during prolonged electrodialysis in solutions containing the aromatic amino acid tyrosine. With increased operation time when using MA-41 heterogeneous membranes in tyrosine solution, an increase in hydrophobicity and roughness characteristics of the material surface is detected. A reduction in tyrosine flux through the membrane occurs which is caused by its pores plugging and deposition of the amino acid at the membrane surface induced by tyrosine adsorption and local supersaturation of the solution in the membrane phase. The long-term contact of the anion exchange membrane with a solution of tyrosine leads to some structural changes in the anion exchange material. An accumulation of the studied amino acid with phenolic fragment and tyrosine oxidation products (DOPA, DOPA-quinone) is found and confirmed by IR- and UV-spectroscopy techniques. The organic fouling is accompanied by an increase in density and a decrease in moisture content of the studied membrane. A comparative analysis of the chemical and electrochemical cleaning results for fouled samples of the MA-41 membrane demonstrates a partial restoration of the material transport characteristics using electrochemical cleaning in the intensive current mode of electrodialysis. The best efficiency of regeneration is reached when carrying out chemical cleaning with a solution of hydrochloric acid, providing almost complete restoration of the membrane characteristics. Full article
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20 pages, 4397 KiB  
Article
Predicting Silica Deposition from Superheated, Pressurized Steam Using Numerical Modeling of Nucleation, Agglomeration and Deposition
by Silje Bordvik, Titus S. van Erp, Seniz Ucar and Erling Næss
Energies 2023, 16(19), 6906; https://doi.org/10.3390/en16196906 - 30 Sep 2023
Cited by 3 | Viewed by 1760
Abstract
A model that can be used to quantify silica deposition from superheated depressurized steam is developed. Classical nucleation theory, agglomeration and deposition onto a wall are combined in a numerical model that calculates the concentration profile, the particle size distribution and the deposition [...] Read more.
A model that can be used to quantify silica deposition from superheated depressurized steam is developed. Classical nucleation theory, agglomeration and deposition onto a wall are combined in a numerical model that calculates the concentration profile, the particle size distribution and the deposition in a flow through a pipeline after a sudden increase in supersaturation. The work presented here is an important step in understanding the mechanisms governing precipitation from supercritical and superheated steam as produced by deep geothermal wells drilled in magmatic areas. The power potential in such systems can be significantly higher than for conventional systems if utilized efficiently. The presented results can be applied to improve industrial designs and decrease energy costs. The model predicts the amount of precipitation along a pipe at various supersaturations, and the resulting deposition velocity in a straight pipe correlates fairly well with recent experimental results. There is a high number of nanocolloids formed close to the pressure reduction position, where deposition is at its maximum. Downstream, larger agglomerates develop, and deposition decreases as the number of particles and the overall concentration decreases. The local maximum deposition rate increases with increasing supersaturation. The calculations show that deposition mechanisms are as important as the chemical process of solidification when estimating where and how most material will be deposited. The rapid formation and deposition of solids predicted indicate that depressurization along with solid capture could be used to rid fluid of silica. Full article
(This article belongs to the Section J: Thermal Management)
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13 pages, 5081 KiB  
Article
Fine Blanking of Austenitic Stainless Steel Gears Using Carbon-Supersaturated High-Speed Steel Tools
by Tatsuhiko Aizawa and Kenji Fuchiwaki
Machines 2023, 11(9), 896; https://doi.org/10.3390/machines11090896 - 9 Sep 2023
Cited by 1 | Viewed by 1779
Abstract
Austenitic stainless steel gears were fabricated via the fine blanking process that can be used for mass production. A carbon-supersaturated (CS)-matrix high-speed steel punch was prepared to minimize the adhesive and abrasive wear damage. Its edge profile was tailored and finished to control [...] Read more.
Austenitic stainless steel gears were fabricated via the fine blanking process that can be used for mass production. A carbon-supersaturated (CS)-matrix high-speed steel punch was prepared to minimize the adhesive and abrasive wear damage. Its edge profile was tailored and finished to control the local metal flow around the punch edges and edge corners. This CS punch was utilized in fine blanking the AISI304 austenitic stainless steel gears. Ball-on-disc (BOD) testing was first employed to describe the frictional behavior of the CS tool steel disc against the AISI304 stainless steel balls. SEM-EDX analysis on the wear track revealed that a free-carbon tribofilm was formed in situ in the wear track to prevent adhesive wear via galling on the tool steel disc. No significant adhesive or abrasive wear was detected on the punch edges and punch edge corners after continuously fine blanking with 50 strokes. AISI304 gears were produced to have fully burnished surfaces. Their pitches, widths and circles were measured to evaluate their gear-grade balancing during the fine blanking process. The stabilized gear-grade balancing in JIS-9 to JIS-10 grades was attained for these as-blanked AISI304 gears without finishing processes. Full article
(This article belongs to the Section Material Processing Technology)
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