Morphology Of Deposits Research Articles

Ash deposition characteristics of flue gas across a tube using the Eulerian multiphase model with dynamic mesh technique

The ash deposition problem majorly affects the stability, safety, and economy of industrial production processes. To investigate the transient ash deposition characteristics of the flue gas flowing across a tube, the Eulerian multiphase model combined with a dynamic mesh technique is first used in this work. The deposition and the removal processes are both taken into account. Four deposition mechanisms are considered in the deposition process, including Brownian and eddy diffusion, gravity, thermophoretic, and turbophoretic forces. Based on the experimental verification results, it is found that the Eulerian multiphase model combined with a dynamic mesh technique can more accurately predict the ash deposition behavior. The overall fouling characteristics are analyzed by the changes in net deposition mass and deposition morphology under seven different working conditions. The results showed that the ash deposits are mainly formed in two regions: β = 165° ∼ 195° and β = 305° ∼ 55°. In addition, one peak is observed in the deposition region on the windward side, and three peaks exist in the deposition region on the leeward side. The periodic shedding regularity of vortices, the separation process of the boundary layer, and the flow patterns of each feature point on the tube surface are studied to investigate the influence of the flow field characteristics on the deposition characteristics. In addition, the causes of the ash deposition in various locations are discussed in detail from the perspective of the deposition mechanism. The findings of this study are beneficial for understanding the ash deposition process and provide an improved approach for ash deposition simulation.

The Effect of Pulse Current on Electrolytically Plating Nickel as a Catalyst for Grafting Carbon Nanotubes onto Carbon Fibers via the Chemical Vapor Deposition Method

Carbon nanotubes (CNTs) can be directly grafted onto the surface of carbon fibers using the chemical vapor deposition method, in which nanometer-order nickel (Ni) particles, serving as catalysts, are plated onto the surface of carbon fibers via electrolytic plating. In our previous studies, in which a direct current (DC) was used to electrolytically plate Ni onto carbon fibers as a catalyst, the site densities and diameters of Ni particles increased simultaneously with the plating time, making it difficult to independently control the site densities and diameters of the particles. On the other hand, pulse current (PC) plating is attracting attention as a plating technique that can control the deposition morphology of nuclei. In this study, we clarify the effect of the parameters of the PC on the particle number per unit area (site density) and the particle diameters of Ni particles plated onto the surface of carbon fibers, using the PC to electrolytically plate Ni. Electrolytically plating Ni onto carbon fibers (via PC) after the removal of the sizing agent enable Ni particles with sparser site densities and larger diameters to be plated than those plated via DC. Using Ni particles with sparse site densities, it is shown that CNTs with sparse site densities can be grafted.

Comparative Study of Lithium Halide-Based Electrolytes for Application in Lithium-Sulfur Batteries

Among the next-generation energy storage technologies, lithium-sulfur batteries are considered one of the most appealing solutions owing to their remarkable theoretical capacity. However, to become commercially competitive, there is a strong need to address some issues still characterizing this technology. One of the explored strategies is the optimization of the electrolyte formulation. To this aim, we compared 1,3-dioxolane/1,2-dimethoxyethane-based electrolytes containing two lithium halides, i.e., lithium bromide (LiBr) and lithium iodide (LiI), with lithium bis (trifluoromethane)sulfonylimide (LiTFSI) as a reference electrolyte. The obtained results show how the donicity of the lithium-salt anions might affect the solid electrolyte interphase stability and the lithium sulfide deposition morphology, therefore influencing the electrochemical performance of the cells. Among the tested electrolytes, the sulfur cell containing LiBr salt exhibited the best electrochemical performance maintaining a specific capacity of 900 mAh g−1 at C/4 and a stable trend along cycling at 1C with a specific capacity of about 770 mAh g−1 for 200 cycles.

Polypropylene pyrolysis and steam reforming over Fe-based catalyst supported on activated carbon for the production of hydrogen-rich syngas

The purpose of this study is to explore a method for the high-yield production of hydrogen by pyrolysis and steam reforming of polymer plastics. The developed Fe-based catalyst supported on activated carbon was applied to reactions with polypropylene for hydrogen production. The effects of iron loading (%) in the catalyst, the total catalyst amount, and the water content in the reaction atmosphere on the performance of hydrogen and gas production were investigated. Under the optimal conditions, the hydrogen yield without water added reached 38.73 mmol/gPP, and this yield was significantly improved by adding water into the reaction atmosphere. By optimizing the amount of water added, the hydrogen yield reached 112.71 mmol/gPP. The surface morphology and structural components of the fresh and used catalysts were characterized, and the morphology and quantity of carbon deposition on the catalyst were analysed. The catalytic stability of the 15Fe/AC catalyst was determined by repeating the test 10 times under the optimal reaction conditions. As the reaction time increased, the selectivity of the catalyst for hydrogen decreased and that for hydrocarbons increased. Moreover, the experimental method used in this study had excellent hydrogen production capacity. Thus, this study provided a novel method for the high-efficiency production of hydrogen by pyrolysis and steam reforming of polymer plastics.

Oriented growth of cobalt electrodeposits assisted by an interfacial flow of bubbles

High-quality Co products are desirable for a variety of applications due to its unique properties. Herein, an interfacial field of flowing bubbles was used to modify the microstructure of Co deposits in the electrowinning process. The effect of flowing bubbles on morphology, crystallographic structure and impurities of Co deposits were investigated. The nucleation and growth of Co deposits were discussed based on chronoamperometric experiments and sampling experiments. The results indicated that the microstructure of Co deposits was effectively modified by an external field of flowing bubbles. The Co deposits prepared in a quiescent electrolyte were porous and inhomogeneous, while the deposits prepared by using the flowing bubbles were compact and uniform. The nucleation and growth modes of Co deposits were also altered by the flowing bubbles. Preferentially oriented grains in the (110) direction were formed by instantaneous nucleation and screw dislocation growth of the deposits. Improvements in microstructure and crystallographic orientation were able to enhance the purity of Co deposits.

Incorporation of Embedded Protective Layers to Circumvent the Low LiNO3Solubility Problem and Enhance Li Metal Anode Cycling Performance

Lithium nitrate (LiNO3) is attracting attention as a promising additive for dendrite suppression owing to its formation of Li3N during electrochemical decomposition and the formation of a spherical-like Li deposition morphology. However, LiNO3 has very low solubility in carbonate electrolytes, and it is continuously decomposed during cycling; thus, we infuse it into a ceramic composite protective layer coated on a thin Li metal surface (thickness: 20 μm) to act as a reservoir during battery cycling. This allows for a slow release of LiNO3 into the electrolyte during cycling, the formation of a Li3N-infused solid electrolyte interface layer, and dendrite suppression. Here, this results in enhanced Li/Li symmetric cell cycling performance for ∼345 h at 0.5 mA cm–2 (0.25 mAh cm–2) and ∼250 cycles, with ∼96% initial discharge capacity retention and ∼99% Coulombic efficiency for Li/LMO cells. Because of the facile nature and effectiveness of the process, the LiNO3 embedded protective layer has the potential to enhance the performance of thin Li metal anodes in Li metal batteries.

Morphological peculiarities of the lithium electrode from the perspective of the Marcus-Hush-Chidsey model

This study employs the kinetics framework of Marcus-Hush-Chidsey (MHC) to investigate the charge transfer at the interface of lithium electrode and electrolyte in lithium(ion)-batteries. The charge-transfer rate constant is evaluated for different facets of lithium, namely (1 0 0), (1 1 0), (1 0 1), and (1 1 1) as a function of surface charge density with the aid of density functional theory (DFT) calculations. The results highlight and quantify the sensitivity of the rate of lithium plating and stripping to the surface orientation, surface charge density, and charge-transfer over-potential. An intrinsic kinetics competition among the different surface orientations is identified together with an asymmetry between the lithium plating and stripping and showcased to influence the deposit morphology and surface protrusions and indentations.

Quaternary lacustrine carbonate deposits of the Great Basin, USA: Impact of climate, tectonics and substrate

ABSTRACTThe Great Basin included several lacustrine systems that accommodated extensive carbonate buildups: the Lahontan on the western side (dating back to 48 kyr cal bp), and the Bonneville (from 30 to 11.5 kyr cal bp) and Great Salt Lake (starting 11.5 kyr cal bp) on the eastern side of the basin. The eastern lakes show a transition from freshwater to hypersaline conditions. In contrast, the western lakes do not show any significant change from the originally prevailing freshwater conditions. Mapping of the carbonate buildups in the different lakes settings enables a comparison of a biotic versus an abiotic composition of the carbonate buildups, their morphologies and their specific spatial distributions. The morphology, size and distribution of the carbonate deposits are predominantly governed by seasonal to long‐term water level fluctuations, particular geomorphological heritage, fault‐induced processes, groundwater seepage and substrates. All of the lakes show a palaeoshoreline distribution with some buildups containing crusts, hemispheroid domes, and parts of complex domes resulting from climate‐induced lake level variations. However, the presence of columns and complex domes made up of mixed biotic/abiotic carbonates in the western Great Basin is related to the influx of groundwater. Winnemucca Lake and Pyramid Lake contain bigger buildups than the ones observed in the eastern Great Basin lakes. The presence of these large size buildups and thinolites in the Lahontan lacustrine system are a consequence of local hydrological processes associated with influenced groundwater flows through specific sedimentary structures (for example, from springs and delta fronts) and faults. This contrast in the distribution, composition and size of the buildups between the two sides of the Great Basin suggests local changes in water chemistry (for example, [Ca2+]) and groundwater influxes. This work provides a novel conceptual model for the formation of abiotic and/or biotic carbonate buildups in lacustrine settings.

Spontaneous Lithiophilic and Lithium-Ion Conductive Functional Layer Formation Enabled by Solution-Casted Zinc Nitride for Highly Stable Lithium Metal Electrode in Carbonate Electrolyte

To improve the reversibility of the Li metal negative electrodes, the simultaneous formation of individually functionalized zinc metal and lithium nitride during the spontaneous conversion reaction of zinc nitride particle is conducted by casting of zinc nitride particles on the lithium electrode. Lithiophilic zinc metal reduces the nucleation polarization of the lithium electrode, whereas the highly ionic conductive and electronically insulating Li3N decreases the concentration polarization from the facile ion conduction and suppression of further electrolyte decomposition during Li plating and stripping. Both these sophisticated characteristics resulted in an improvement in the deposition morphology of lithium electrode, thereby enhancing the reversibility of lithium electrode. Consequently, the cycleability improvement of Li/LiNi0.8Co0.1Mn0.1O2 is achieved through the application of zinc nitride surface-treated lithium electrode.

Re-appearance of precipitated aragonite crystal fans as evidence for expansion of oceanic dissolved inorganic carbon reservoir in the aftermath of the Lomagundi-Jatuli Event

The initial accumulation of atmospheric oxygen is marked by the unprecedented positive δ13Ccarb excursions of the Lomagundi-Jatuli Event (LJE) and records an interval of abnormal O2 production through elevated rates of organic carbon burial. Emerging evidence suggests that the post-LJE atmosphere-ocean system might have suffered a significant deoxygenation. These dynamic perturbations in the oceanic redox state and biogeochemical cycles would have led to fundamental changes in carbonate precipitation dynamics. Here, we report the discovery of centimeter-sized crystal fans in the post-LJE Huaiyincun Formation, Hutuo Supergroup in the North China Craton. The hexagonal cross-sections and square terminations suggest that these fan-like dolomitic structures were originally aragonite crystal fans (ACF). Variations of stromatolite morphology and frequent occurrences of storm-related deposits in the Huaiyincun Formation point to repeated cycles of sea level changes. The bedding-parallel distribution of the ACF and the homogeneous δ13C values of the ACF-bearing dolostones are consistent with a primary depositional origin for the ACF. An updated compilation of published records of ACF throughout geological history highlights a clear absence of ACF from the initiation of the Paleoproterozoic Great Oxidation Event until the end of the LJE, and a global reappearance of ACF in the post-LJE late Paleoproterozoic. We propose that the reappearance of ACF is in agreement with the expansion of the oceanic dissolved inorganic carbon reservoir. At the same time, consumption of dissolved oxygen during the oxidation of organic matter might have been stimulated by ferruginous deep seawater, facilitating the formation of Huiayincun ACF.

Silicon electrowinning by molten salts electrolysis.

Electrochemically produced Si in molten salts can be used to fabricate electronic and photovoltaic devices. The major factors influencing the structure and morphology of Si deposits are electrolyte composition, applied current densities and overpotentials, type of precursors, operating temperature, and electrodeposition duration. For Si electrodeposition, a less corrosive electrolyte with the ability to dissolve Si species and easily soluble in water should be used. This review provides a brief analysis of the Si production by electrolysis in molten salts.

Geomorphometric and Geophysical Constraints on Outlining Drained Shallow Mountain Mires

Long-term draining of peatlands results in transformation of vegetation and obliteration of their morphological features. In many areas, efforts are made to restore the original ecosystems and increase their water retention potential. Using combined analyses of a LiDAR-based digital terrain model (DTM), colour-infrared (CIR) imagery data, ground-penetrating radar (GPR) data and electrical resistivity tomography (ERT) data, we tested the applicability of these methods in outlining the extent and subsurface structure of drained mires located in the Stolowe Mountains National Park area, Poland. The LiDAR-DTMs enabled parameterisation of physiographic features of the mires and determination of their extent, runoff directions and potential waterlogging areas. CIR analysis enabled classification of vegetation types. GPR prospecting revealed the bedrock morphology, thickness and internal structure of the peat deposits, showing that this technique can also provide data on variability in the decomposition of phytogenic deposits. The obtained ERT sections indicate both the thickness of peat deposits and variability in the bedrock internal structure. The results show that integrated analyses of data obtained with different methods can be an effective tool in outlining the original extent of peatlands, with potential application in the planning of peatland ecosystem restitution.

Sensitivity and Calibration of Three‐Dimensional SPH Formulations in Large‐Scale Landslide Modeling

AbstractNumerical prediction of landslide runout and deposition is important for estimating landslide risk and developing mitigation plans. The choice of a suitable model and its parameters and a confident calibration strategy are crucial for numerical simulations. Here, we evaluated two constitutive models with a three‐dimensional smoothed particle hydrodynamics (SPH) method by simulating the catastrophic 11 October 2018 Baige landslide. The results indicate that both the soil mechanic and fluid models can capture the dynamic runout and deposition morphology while using different values of input parameters. A point‐wise comparison of deposit elevation can minimize the calibration error. Numerical models were constrained accurately by utilizing both the static observation data and dynamic seismic signals. The effects of friction on deep‐seated landslides motion and deposition are more significant than cohesion. The 3D model includes the effects of shear stresses and velocities inside the material body, resulting in a reduced friction coefficient compared to the 2D model (e.g., depth‐averaged model). Our study highlights the potential of the 3D SPH method for modeling large‐scale complex landslides.

Effectiveness of different additives on slagging and fouling tendencies of blended coal

Indonesian coal reserves are dominated by medium and low-rank coals. Despite being economically profitable, low-quality coals can trigger ash-related problems in a boiler, such as slagging and fouling. Suitable additives can be useful to overcome the issue of high-alkali coals. The main objective of this study is to determine the effectiveness of the three additives in reducing slagging and fouling risks using a drop tube furnace. Aluminum silicate-based, aluminum-based, and magnesium-based additives were used in coal combustion to comprehensively evaluate ash fusion temperature, thermal properties, ash deposit, emission, and ash mineral morphology. The results showed that additives in high-risk coal/blended coal could reduce ash sintering during the combustion. It can lower the ash fusion temperature yet reduce slagging ash deposits and flue gas emissions. Si–Al, Al, and Mg minerals play a role in increasing the ash melting point. Among three additives, the aluminum-based additive can increase the Rmax value, resulting in more stable conditions during the combustion.

Propagation Modeling of Rainfall-Induced Landslides: A Case Study of the Shaziba Landslide in Enshi, China

Geological disasters, especially landslides, frequently occur in Enshi County, Hubei Province, China. On 21 July 2020, a large-scale landslide occurred in Enshi due to continuous rainfall. The landslide mass blocked the Qingjiang River, formed a dammed lake and caused great damage to surrounding roads and village buildings. In this study, the geomechanical properties of the landslide mass were obtained through field surveys. A three-dimensional topography model of the slope was established using the particle flow code (PFC) and the numerical parameters of the model were calibrated. A 3D discrete element model (DEM) was used to simulate the propagation of Shaziba landslide, and the dynamic behavior of the landslide was divided into five stages. The simulation results show that the landslide movement lasted approximately 1000 s. The maximum average velocity of the landslide reached up to 7.5 m/s and the average runout distance was about 1000 m. The simulated morphology of the landslide deposits was in good agreement with the field data. In addition, the influence of effective modulus on the calculation results was analyzed. The results indicate that the propagation behavior of a landslide and the morphology of landslide deposits are closely related to the effective modulus in the contact model of the PFC3D.

Unraveling the Influence of Li+‐cation and TFSI−‐anion in Poly(ionic liquid) Binders for Lithium‐Metal Batteries

AbstractIon transport in composite electrodes plays a key role in the electrochemical performance of lithium‐metal batteries (LMBs), particularly at high current densities, and hence, some works have suggested the use of ionic conducting polymers as binders. Herein, in order to assess the importance of the type of ion conduction in binders, two poly(ionic liquid) polymers were analyzed as binders in LiFePO4 (LFP) cathodes: poly(lithium 1‐[3‐(methacryloyloxy)propylsulfonyl]‐1‐(trifluoromethane sulfonyl) imide) (PMTFSI−Li), and poly(diallyldimethylammonium bis(trifluoromethane sulfonyl)imide) (PDADMA−TFSI). Their functionalities allow modulating the individual transport of their counter‐ions, Li+ and TFSI−, respectively; in comparison with conventional PVDF binder. Thus, LFP−C‐Binder cathodes, namely C−PVDF, C−PDADMA−TFSI and C−PMTFSI−Li, were evaluated in LMBs. C−PMTFSI−Li exhibited the best performance reaching the theoretical specific capacity (170.3±0.8 mAh g−1) at C/10, an outstanding capacity at 10 C (100.6±0.5 mAh g−1), and long lifespan (>500 cycles at 1 C). C−PDADMA−TFSI showed good long‐term cycling and high performance at high C‐rate, while C−PVDF ended up fading before reaching 500 cycles. Surprisingly, it was observed that the presence of ionic binders into the cathode formulation influenced on Li0 metal deposition morphology, leading to a more homogeneous plating (specially PMTFSI−Li) in comparison with PVDF; and therefore, exhibiting a mitigation of mossy lithium growth.

Crystal facet correlated Zn growth on Cu for aqueous Zn metal batteries

Aqueous Zn metal batteries are one of the most attractive systems for large-scale energy storage applications. Planar Cu substrates are widely utilized as current collectors for Zn anodes. Although different approaches have been applied to improve performance of Zn anodes, the nature of native Cu current collector for Zn growth has not been fully understood. In this work, we explore native planar Cu foils and find that the Zn anode exhibits distinct electrochemical properties on the Cu current collectors with different dominant crystal facets. Specifically, in asymmetric Cu-Zn cell tests, the Zn anodes using Cu foils with Cu-100 or Cu-110 dominant crystal planes exhibit the first-cycle CE of 95% with plate-like deposition morphology and long cycle life of 1000 h, which is a significant improvement compared to that with Cu-111 dominant crystal facet. In addition, activated carbon-Zn/Cu hybrid capacitors based on Cu-100 or Cu-110 for Zn anodes exhibit higher specific capacity and longer cycle life than that of Cu-111. Further, DFT calculations show that the adsorption energies of Cu-100 and Cu-110 crystal facets during Zn deposition are much higher than that of the Cu-111 crystal facet, validating the significant crystal facet selectivity on the Zn anode chemistry. This work reveals the crystal facet correlation with the Zn anode electrochemical performance, providing opportunities for the future development of high-energy and long-life Zn metal batteries.

Asphaltene Precipitation and the Influence of Dispersants and Inhibitors on Morphology Probed by AFM

Bridging the gap between laboratory-scale experiments and actual oilfield operations is a complex task that requires a compromise between real (authentic) fluids and model systems. Commercial products (i.e., asphaltene inhibitors and dispersants) are often designed to target a wide range of operating conditions and compositions of crude oils, which means that the performance becomes almost case-specific. Through Atomic Force Microscopy (AFM) imaging and Transmission/Backscattering signals (T/BS), the morphology of asphaltene deposits and the mechanisms that eventually lead to precipitated material were evaluated. Two different models (starting solutions) with four different n-alkanes were used to induce variability in asphaltene agglomeration and subsequent precipitation paths. It was found that increasing the carbon number shifted the observed precipitation detection time (T/BS data suggested a shift in the order of ~1000 s when comparing low and high carbon numbers) and influences the density of the precipitated material under static and a sufficiently high concentration of solvent conditions. Further analysis on the morphology of the resulting material after the addition of commonly used chemicals showed that asphaltene stability through inhibition (i.e., blockage or crowding of potential active sites) led to smaller complexes. One of the additives (PIBSA) reduced the average height in ~33% and the mean square roughness in ~72%. On the other hand, stability through dispersion (i.e., hindering agglomeration) leads to a polymer-like network bigger in size, noting that in both cases the system remains soluble. The use of APR resulted in an increase of ~41% and ~54% for the same parameters. This insight sheds light on how to devise efficient chemical strategies to prevent flow assurance issues.

Understanding Li creep in Li-metal pouch cells and the role of separator integrity

To realize the advantages of high energy density lithium-metal batteries, their cycle life and safety need to be improved to meet practical and commercial demands. External compression has been shown to improve the performance of lithium-metal batteries through suppressing dendrite growth, densifying the lithium deposit, and improving the lithium deposition morphology. Here, we report the behavior of high-capacity Li||LFP pouch cells in pyrrolidinium-based ionic liquid electrolytes at elevated temperature (50 °C) under various levels of compression and discuss the compression-related mechanisms that affect the performance and failure of the cells. Using scanning electron microscopy, we observed more uniform and less dendritic Li deposition at high levels of compression. However, cell pressure evolution data shows significant lithium metal creep above 800 kPa, effectively limiting the maximum applicable compression. Reducing the testing temperature to 25 °C and maintaining high compression led to suppressed Li creep and extended the cell cycle life by 40%. The adverse effect of lithium creep on the separator is identified as an important mechanism on the pouch cell cycling behavior and is further discussed herein.

Controllable CF4 Plasma In Situ Modification Strategy Enables Durable Zinc Metal Anode.

Zn metal with high specific capacity and low redox potential is deemed to be an ideal anode material for aqueous zinc-ion batteries (ZIBs). However, the serious dendrite problems induced by the uneven deposition of zinc shorten the service life and hinder the development of ZIBs. According to the nucleation and growth mechanism, the charge distribution at the anode interface is the critical factor affecting the deposition morphology. Herein, CF4 plasma technology is applied for the first time to in situ modification of the Zn anode, and then, the uniform nanoscale ZnF2 particles are formed. Due to the excellent ionic conductivity and poor electronic conductivity of ZnF2, the ion and electron distribution at the anode interface is orderly regulated, thus guiding uniform and reversible deposition behavior and restraining the dendrite growth. As a result, the Zn@ZnF2-5 anode exhibits low nucleation overpotential (16 mV), long cycle life (2500 h at 1 mA cm-2 and 1 mA h cm-2), and excellent resistance to high current density (20 mA cm-2) and high discharge depth (16%). Meanwhile, the Zn@ZnF2-5|I2@AC full battery shows remarkable cycle stability (1000 cycles) with ∼10% discharge depth of the anode. The novel and practical CF4 plasma in situ modification strategy provides a new idea for the interface modification of zinc anode.