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In the electrochemical process, Pt nanoparticles (NPs) in Pt-based catalysts usually agglomerate due to Oswald ripening or lack of restraint, ultimately resulting in reduction of the active sites and catalytic efficiency. How to uniformly disperse and firmly fix Pt NPs on carbon matrix with suitable particle size for catalysis is still a big challenge. Herein, to prevent the agglomeration and shedding of Pt NPs, Ni species is introduced and are evenly dispersed in the surface of carbon matrix in the form of Ni-N-C active sites (Ni ZIF-NC). The Ni sites can be used to anchor Pt NPs, and then effectively limit the further growth and agglomeration of Pt NPs during the reaction process. Compared with commercial Pt/C catalyst, Pt@Ni ZIF-NC, with ultralow Pt loading (7 wt%) and ideal particle size (2.3 nm), not only increases the active center, but also promotes the catalysis kinetics, greatly improving the ORR and HER catalytic activity. Under acidic conditions, its half-wave potential (0.902 V) is superior to commercial Pt/C (0.861 V), and the mass activity (0.38 A per mg Pt) at 0.9 V is 4.7 times that of Pt/C (0.08 A per mg Pt). Besides, it also shows outstanding HER performance. At 20 and 30 mV, its mass activity is even 2 and 6 times that of Pt/C, respectively. Whether it is under ORR or HER conditions, it still shows excellent durability. These undoubtedly indicate the realization of dual-functional catalysts with low-Pt and high-efficiency properties.

During twin screw granulation (TSG), small particles, which generally have irregular shapes, agglomerate together to form larger granules with improved properties. However, how particle shape impacts the conveying characteristics during TSG is not explored nor well understood. In this study, a graphic processor units (GPUs) enhanced discrete element method (DEM) is adopted to examine the effect of particle shape on the conveying characteristics in a full scale twin screw granulator for the first time. It is found that TSG with spherical particles has the smallest particle retention number, mean residence time, and power consumption; while for TSG with hexagonal prism (Hexp) shaped particles the largest particle retention number is obtained, and TSG with cubic particles requires the highest power consumption. Furthermore, spherical particles exhibit a flow pattern closer to an ideal plug flow, while cubic particles present a flow pattern approaching a perfect mixing. It is demonstrated that the GPU-enhanced DEM is capable of simulating the complex TSG process in a full-scale twin screw granulator with non-spherical particles.

The two stage technology of porous carbonaceous material obtaining via pyrolysis in inert medium with subsequent activation by steam is well-known. While steam could be a suitable substance for pyrolysis as well, the single-staged technology for waste tires recycling is yet to be developed. A comparative analysis of the characteristics of the carbonaceous materials obtained by the single-staged steam pyrolysis of waste tires was carried out, which could provide theoretical background for development of such technology. The steam pyrolysis was performed in a tubular reactor in an overheated steam medium (500 °C with 5 kg/h mass flow rate). The technical characteristics of the obtained samples were evaluated in context of their potential for further application as absorbent and raw material for the rubber production according to Chemical Abstracts Service No. 1333-86-4. The composition and physical-chemical properties of the obtained samples were studied using BET and thermogravimetric analysis, atomic emission, transmission and scanning electron microscopies, Raman, X-ray diffraction and photoelectron spectroscopies. The results revealed that the structure and properties of all obtained carbonaceous material samples were similar. The samples consisted of amorphous carbon (with a disordered graphite lattice) and contained a significant amount of metal oxides. According to experimental data, zinc was present in the form of ZnO with a binding energy of 1022.4 eV, while sulfur was observed in the form of sulfide and oxysulfide with binding energies of 161.8 and 163.2 eV, respectively. According to electron microscopy, the morphology of samples was represented by a set of spherical agglomerates comprising nanosized particles. According to the BET analysis of the samples, the specific surface area was varieb in range between 52.0 and 66.0 m2/g, the pore volume values were within a range of 0.53-0.87 cm3/g while the average pore size was varied from 412 to 527 A.

Float polishing (FP) is a non-contact polishing method in which a thin layer of fluid is maintained between the workpiece and precision lap by hydrodynamic pressure effect. While it is known to consistently produce atomically flat surfaces with little or no sub-surface damage, the characteristics of polishing fluid flow and material removal have not been studied in-depth. In this research, the underlying mechanism in FP is investigated by means of computational fluid dynamics (CFD) and molecular dynamics (MD) simulation. It is revealed that a fluid gap few microns in height is generated by the wedge effect of slurry. The near wall flow condition is further investigated by direct observation and tracing of cavitation bubbles. Abrasive particle trajectory tracing is carried out with a well calibrated CFD model, and suggests that single abrasive particles move almost parallel to the workpiece surface at a relative speed of around 0.5 mm/s. Next, single abrasive particle interactions with the surface of a Ni crystal are simulated by MD to predict the required conditions in terms of kinetic energy for effective smoothing of the surface. Finally, it is concluded that the material removal mechanism in FP is dependent on a minimum size of nano-abrasive agglomerates of several 100 nm, and the existence of two types of smoothing phenomena: atomic removal and atomic transfer.

In this paper, equilibrium molecular dynamic simulations were used to calculate the thermal conductivity of Cu-Ar nanofluid with various initial aggregation structures at different volume fractions. The microscopic mechanism of the effect of nanoparticle agglomerate aggregation mode on the thermal conductivity of nanofluids was analyzed. Results showed that the particle size is the key factor to determine the aggregation structure of nanoparticles. The enhancement efficiency of diffusion-limited aggregation on the thermal conductivity of nanofluids was found to be greater than that of reaction-limited aggregation, and the effect of different aggregation structures on the diffusion coefficient of nanofluidic systems may be one of the potential mechanisms affecting the thermal conductivity of nanofluids.

Objective: To morphologically analyze, by means of scanning electron microscopy (SEM), agglomerated boards made from rice husk and Hidropul 400, as well as boards made from wood fibers and glue. Methodology: For each 7,3 x 3,6 x 1,5 cm test piece, two samples were taken from the external and internal sections of each one of the boards to be analyzed. Thin-layer graphite coatings were made to each one of them, and, by means of SEM, micrographic shots were obtained in the range from 50x to 2000x. Results: It was evidenced that the panel made from rice husk had damage to its internal structure due to its porosity, the waxy layers of its coating, the high presence of silica, and the presence of water inside the adhesive, showing irregularities in adhesion between particles and low mechanical properties. Conclusions: Although the studied rice husk panel did not achieve the adequate structural properties, it has great applications for interior design. Additionally, due to its porous structure, its potential as a sound-absorbing material is considered. In the same way, the material can be improved by pre-treating the husk or combining it with other, more woody plant fibers such as wood waste, bamboo, coconut fiber, among others. RESUMEN Objetivo: Analizar morfológicamente, por medio microscopía electrónica de barrido (SEM), tableros aglomerados elaborados con cascarilla de arroz e Hidropul 400, así como tableros elaborados a partir de las virutas de madera y pegamento. Metodología: Para cada cada probeta de 7,3 x 3,6 x 1,5 cm, se tomaron dos muestras en las secciones externas e internas de cada uno de los paneles a analizar. Se realizaron recubrimientos de capa fina de grafito a cada una de ellas y, mediante SEM, se realizaron tomas micrográficas en rangos de 50x a 2000x. Resultados: Se evidenció que el panel fabricado con cascarilla de arroz presentaba afectaciones en su estructura interna debido a la porosidad, las capas cerosas de su recubrimiento, la alta presencia de sílice y la presencia de agua dentro del adhesivo, mostrando irregularidades en adherencia entre partículas y bajas propiedades mecánicas. Conclusiones: Aunque el panel a base de cascarilla de arroz estudiado no obtuvo las propiedades estructurales adecuadas, tiene grandes aplicaciones para el diseño de interiores. Además, por su estructura porosa, se considera su potencial como material absorbente del sonido. De igual forma, se puede mejorar el material al hacer un pretratamiento de la cascarilla o combinarla con diferentes fibras vegetales más leñosas como desperdicios de madera, bambú, fibra de coco, entre otros.

ZnO nanoparticles were synthesized from C. sativum adopting green synthesis. Optical property of ZnO particles thus obtained was studied by UV spectral data, size of the particles was determined from XRD studies and morphology established from SEM micrographs. XRD data revealed the hexagonal wurtzite structure of the ZnO sample, size of the particles was about 74 nm obtained from Scherrer equation. ZnO particles appear as an agglomerate of nanoflakes. Investigation of gas sensing property establishes that the material exhibits excellent sensing performances including high gas response, good selectivity, fast response/recovery time.

Gas bubble distribution is considered one of the most critical factors affecting the Industrial Fluid Coking™ process since it influences the formation of wet agglomerates that causes fouling in the stripper section. A multi-phase Eulerian–Eulerian two-fluid method (TFM) coupled with the kinetic theory of the granular flow (KTGF) was used to investigate the hydrodynamics of a bubbling fluidized bed; the goal is to increase the flow of gas bubbles into the first half of the jet cavity formed when liquid is sprayed into the fluidized bed, thus reducing the formation of wet agglomerates. The numerical simulations under different superficial gas velocities, different gas distributor geometries, and different gas distributor inclined angles were carried out. The results showed that the predicted bubble distributions at the injection level under the lab and commercial operating conditions are similar although the particles and gases are different under those two operating conditions. More gas bubbles can be directed to the first half of the jet cavity by either increasing the gas superficial velocity (directing around 20% more gas to the specified area) or using the proposed new gas distributor (directing around 30% more gas to the specified area). The effect of the inlet gas distributor configuration on the bubble distribution is much more substantial when the inclined angle of the gas distributor is large.

In this paper, Al2O3–TiC/ZL101 composites were fabricated via in-situ reaction process with TiO2, Al, graphite and ZL101 powders. Microstructure characteristics, formation mechanism of reinforcements, thermodynamic calculation of reaction, hardness and tribological behavior of the composites were investigated in detail. The distribution of Al2O3 and TiC precipitates changes from agglomerate to relative uniform with the content rise of strengthening phases. Al2O3 precipitates are irregular spherical with the average size of 3–5 μm. The shape of TiC particles is cube or polygon and the size is about 2–4 μm. The thermodynamic calculation of reactants further proves the reinforcements formation, which is consistent with the microstructure observation and X-ray diffraction result. The formation mechanism of TiC and Al2O3 mainly is by diffusion and precipitation. The microhardness and wear performance of composites remarkably improve, friction coefficient and wear weitgh loss decrease with the content rise of TiC and Al2O3 phases. The microhardness of C3 composite increases from 93HV to 162HV, the friction coefficient (FC) and weight loss decrease from 1.15 and 0.128g to 0.43 and 0.066g compared with the ZL101 alloy. C3 composite has the best wear property for the highest hardness, the lowest FC and weight loss. Microstructure refinement, uniform dispersion of TiC and Al2O3 precipitates and the strong interfacial adhesion between reinforcements and matrix are attributed to the better wear performance of composites. The wear surface morphology shows that the wear mechanism of ZL101 alloy is mainly adhesive wear while the wear style of the composites is abrasive wear.

A CFD-DEM coupled with a cohesive contact model is developed for simulation of a Wurster fluidized bed with heat and mass transfer. First, the water evaporation and cohesive contact sub-models are tested, respectively. Second, a Wurster fluidized bed with heating, drying, and wet particle fluidization is simulated. Results show that the particle temperature in the bottom and draft tube rises faster than that in the annular region, which leads to the probability density distribution of the particle temperature presents two peaks. The circulation pattern also has a significant effect on particle drying. Under conditions with a small amount of liquid injection, the water evaporates immediately and the particles are fluidized normally. Increasing the liquid injection rate, the stability of the particle circulation decreases. Under conditions with significant particle cohesion, large agglomerates are formed and the fluidization breaks down. The current study provides an effective method for studying hydrodynamics of Wurster fluidized beds with simultaneous processes of heating, drying, and wet particle fluidization.

The article is devoted to the analysis of the normative indicators of the operation of hopper semi-wagons by time during the transportation of agglomerate from the sinter factory to the blast furnace. For the first time, questions were raised about the irrationality of intra-factory transportation of agglomerate by rail over long distances. Graphs of the transport and technological cycle are constructed. The results of calculations of the operation of mobile warehouses with agglomerate according to the normative and actual schedule of their implementation are given., Стаття присвячена аналізу нормативних показників роботи напіввагонів-хоперів за часом при виконанні перевезень агломерату з аглофабрики до доменного цеху. Вперше порушені питання про нераціональність внутрішньозаводських перевезень агломерату залізничним транспортом на великі відстані. Побудовані графіки транспортно-технологічного циклу. Наведені результати розрахунків роботи рухомих складів з агломератом за нормативним та фактичним графіком їх виконання.

The present study evaluates elastic and inelastic contact forces in predicting the fluidization characteristics of irregularly shaped Titania nanoparticle agglomerates in a bench-scale conical fluidized bed. At first, experiments were performed to identify the mutual effects of gas velocity and agglomerate size on the instantaneous pressure, bed pressure drop and bed expansion ratio. Rigid complex-agglomerates (∼100−200 μm) were mainly formed in the partially fluidized regime, while soft simple-agglomerates (∼20−70 μm) were primarily formed in the spouting regime. The simulations were performed through the CFD-DEM approach. The error analysis of results in the partially fluidized regime revealed that the combination of Hertz-Mindlin and Johnson-Kendall-Roberts (HM + JKR) model led to a better prediction of the bed pressure drop and bed expansion ratio than the spring-dashpot (LSD) model. In the transition flow regime, the Hysteretic model led to better results of the instantaneous pressure values than those proposed for other flow regimes. In the spouting flow regime, the HM and Thornton models led to over-estimation of bed pressure drop when compared to the LSD model. The comparative results of this study provide promising new insights into the collision mechanism of polydisperse agglomerates in different flow regimes for industrial aspects.

The chemical agglomeration technology can effectively remove fine particles during coking coal loading and unloading. Aiming at the traditional agglomerator has the high price and secondary pollution problems, the new method of viscosifying fine particles was established. The fine particles were contacted with the soap solution through the cyclone circumfluence to increase viscosifying and agglomerate. The regulation and control of uniform humidification of whole particles were studied, and the relations among humidification, agglomeration, dust suppression and agglomeration conditions of fine particles were discussed. By establishing the agglomeration model and mechanical model, the influence of agglomeration on the force and velocity distribution of particles was analyzed based on CFD. The results showed that the soap solution has a strong effect on agglomeration of particle size less than 0.5 mm. The adsorption and flocculation of the polymer chain in the soap can promote the agglomeration of the fine particles. In the area of vortex formed by swirling air, with the mass addition ratio of soap powder increases from 5% to 15%, the coating efficiency of fine particles increases from 82% to 96%. The agglomeration results show that the average concentration of the fine particles decreases by nearly 20% finally.

A survey of cadmium plated field return hardware showed ubiquitous cadmium whisker growth. The most worn and debris-covered hardware showed the densest whisker growth. Whiskers were often found growing in agglomerates of nodules and whiskers. The hardware was rinsed with alcohol to transfer whiskers and debris from the hardware to a flat stub. Fifty whiskers were studied individually by scanning electron microscopy (SEM), including energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). Most of the whiskers were single crystal, though three were found to contain grain boundaries at kinks. The whiskers ranged from 5 to 600 μm in length and 80 pct showed a < $$\overline{1 }$$ 2 $$\overline{1 }$$ 0> type growth direction. This growth direction facilitates the development of low energy side faces of the whisker, (0001) and {1010}.

High-resolution transmission electron microscopy (HRTEM) was used to observe the soot particles emitted from gasoline direct injection (GDI) engine equipped with metallic particulate filter (GPF). The changes of microscopic morphology and structure of the soot particles at pre-GPF and post-GPF were studied at a fixed speed of 1500 r/min and 25 %, 50 % 75 % and 100 % load, respectively. Furthermore, the micro-parameters of the primary particles that make up the soot particles were analyzed. The results show that the primary particles are approximately spherical, and agglomerate to form irregular shapes such as chains, branches and rings. The load and GPF have no significant influence on the microscopic morphology of the soot particles, the fractal dimension of soot particles at both ends of the GPF increases with the increase of load. Under the experimental conditions of the engine, most primary particles consisting of the soot particles are “shell-core” structure; The fringe length, tortuosity and interlayer spacing of the primary particles at pre- and post-GPF are monomodal. Among them, the average fringe length increases with the increase of load, while both the average tortuosity and average interlayer spacing change the opposite. These indicated that the degree of graphitization of the soot particle increases with the increasing load. Load and GPF only affect the micro-structure parameters of the primary particles and have no effect on its distribution.

We describe an in situ facile synthetic approach to prepare carbon quantum dot (CQD) fluorescent markers (FMs) for polyethylene (PE) in the presence of agglomerated silica nanoparticles (SiO2 NPs) under mild reaction conditions. First SiO2 NPs, prepared by the Stöber method, were dispersed in toluene. This dispersion was added to a PE solution in toluene. After heating (either in air or under Ar) a fluorescent mixture was obtained. After drying, PE films were obtained by compression molding, which showed strong blue fluorescence, attributed to CQDs. SiO2 NPs loading values varied between 0.5 and 4 wt %. Subsequent to isolation, the fluorescent CQDs were characterized by TEM, UV-vis, and fluorescence spectroscopy. TEM imaging unveiled a lattice spacing value of 0.21 nm of the isolated fluorescent particles which is typical for (100) graphite plane lattice spacing in CQDs. UV spectroscopy and fluorescence measurements show characteristic absorption and excitation spectra for the aromatic core and oxidized surface defects typically observed for CQDs. The emission maximum for PE/CQD samples increased from 394 to 408 nm when the reaction temperature was decreased from 110 to 90 °C, which is attributed to increasing oxygen content in the reaction mixture upon decreasing the reaction temperature. When the reaction was performed under Ar, the PE/CQD samples emitted in the ultraviolet region (286 nm). Finally, we demonstrated that PE samples marked with CQDs can be easily visually identified upon irradiating with 367 nm light. Thus, the marked PE can be used, for example, as a labeling ingredient in master batches for component identification and in recycling.

As a kind of frequent bad weather, Agglomerate fog is a serious danger to people's safe driving, especially on the highway. Therefore, the research on the detection of fog is of great practical significance to ensure the safety of pedestrians. This paper proposes a shallow convolutional neural network for agglomerate fog detection in images, including the framework of the network and the detailed design of each component. Firstly, the image is divided into several sub-images; and then a shallow convolutional neural network is constructed and employed to identify the existence of fog for each of the sub-area images; lastly, the decision results of each sub-area images were integrated to determine whether the whole image contained agglomerate fog. A large quantity of simulation data and real data were used to test the performance of the proposed method, the experimental results show that the presented method can achieve more than 90% detection accuracy, which demonstrated that the advantage of the proposed method comparing with several existed methods.

Aluminum powder can increase the specific impulse and improve the combustion performance of a solid propellant; however, agglomeration can result in the loss of two-phase flow, a decrease in specific impulse of the propellant, and an increase in the thermal protection pressure of the motor structure. This study employs digital inline holography, which offers the advantage of non-contact three-dimensional measurements, to investigate the agglomeration particle size near the burning surface. This study aims to quantitatively analyze these particle size data to determine the effects of pressure, ammonium perchlorate particle size, coarse and fine ammonium perchlorate content ratio, and aluminum particle size on the agglomeration particle size distribution. The experimental results indicate that increasing the pressure from 0.1 MPa to 0.8 MPa reduces the average particle diameter of agglomeration by at least 9.6%, results in a more concentrated agglomeration particle size distribution, and decreases the volume and number proportion of agglomeration by approximately 7% and 17%, respectively. Furthermore, when the particle size of ammonium perchlorate decreases from 250 μm to 90 μm, the agglomeration particle size distribution becomes more concentrated, the average diameter of agglomeration decreases by at least 37.4%, and the number and volume proportion of agglomeration decrease by approximately 13% and 44%, respectively. The ratio of coarse and fine ammonium perchlorate content has a nonlinear effect on agglomeration. When this ratio is 0.6, the average agglomerate diameter decreases by at least 16%, the agglomeration particle size distribution is more concentrated than that the ratio is 0.39 and 1.29, and the agglomeration number and volume fraction decrease by more than 6% and 32%, respectively. Moreover, decreasing the initial aluminum particle size from 30 μm to 15 μm reduces the average agglomeration particle diameter by more than 21.6%, results in a more concentrated agglomeration particle size distribution, however, increases the number and volume proportion of agglomeration by approximately 17% and 8%, respectively. The conclusions of this study are expected to be significantly helpful in optimizing propellant formulation, reducing the particle size of aluminum agglomeration, and improving the combustion performance of propellants.

The size distribution and morphology evolution of the initial agglomerates on the burning surface of aluminized composite propellants have a strong influence on the agglomeration mechanism and size of condensed products. However, most previous research has focused on the establishment of size prediction models, and research on other characteristics of initial agglomerates is still lacking. The characteristics of the size distribution and evolution of the morphology of the initial agglomerates are investigated in this study. Analysis of the size distribution of the initial agglomerates shows that the distribution is regular in the stable combustion stage, and the agglomerates in this stage show weak agglomeration. The morphologies of the initial agglomerates are found to comprise coral-like structures composed of small alumina particles with strong fluidity in Stage (a), in which the effect of accumulation is dominant. In Stage (b), the initial agglomerates exhibit a relatively stable form of a ‘spherical structure + coral-like bond’, and the effects of accumulation and combustion are in dynamic equilibrium. In Stage (c), the initial agglomerates are spherical with an oxidation cap, and this stage is dominated by combustion. Through analysis of the characteristics of the size distribution and morphology evolution of the initial agglomerates, the agglomeration mechanism of aluminum particles on the burning surface is further clarified, which provides the foundation for further research.

Актуальность исследования обусловлена отсутствием эффективных методов и средств борьбы с загрязнением атмосферы субмикронными частицами размером менее 2,5 мкм. Применяемое для этих целей ультразвуковое воздействие не позволяет обеспечить степень укрупнения дисперсных частиц, достаточную для их осаждения или улавливания существующим газоочистным оборудованием. Как показывают экспериментальные исследования, даже при максимальном уровне звукового давления (при превышении которого инициируется обратный процесс - диспергирование капель или разрушении агломератов частиц) эффективность ультразвуковой коагуляции оказывается недостаточной, особенно при малой счетной концентрации частиц. Это обуславливает необходимость выявление новых физических эффектов и разработки новых способов воздействия, повышающих эффективность коагуляции тонкодисперсных частиц. Цель: разработка способа для повышения эффективности ультразвуковой коагуляции частиц размером менее 2,5 мкм за счет формирования вихревых акустических течений в тонком воздушном промежутке между излучателем и отражателем и создание устройства для его практической реализации. Результаты. Предложен новый способ и устройство для очистки газов от дисперсных частиц размером менее 2,5 мкм за счет увеличения времени ультразвукового воздействия на каждую частичку и создания зон локального увеличения концентрации субмикронных частиц. Это обеспечивается за счет формирования вихревых потоков между излучающей (в виде изгибно-колеблющегося диска) и отражающей поверхностями. Локальная зона повышенной концентрации частиц формируется в периферийной области вихря за счет дрейфа частиц под действием центробежных сил из центральной области вихря к его периферии. Предложенный способ обеспечивает повышение эффективности с 13 до 50 %, в зависимости от исходной концентрации дисперсных частиц. The relevance of the research is caused by the lack of effective methods and means of combating atmospheric pollution with particles less than 2,5 microns in size. The ultrasonic effect used for these purposes does not allow ensuring the degree of coarsening of dispersed particles sufficient for their sedimentation or capture by the existing gas cleaning equipment. Experimental studies show that even at the maximum sound pressure level (above which the reverse process - the dispersion of drops or the destruction of particle agglomerates - is initiated), the efficiency of ultrasonic coagulation is insufficient, especially at a low counting concentration of particles. This necessitates the identification of new physical effects and the development of new methods of ultrasonic exposure, providing an increase in the efficiency of coagulation of fine particles. The main aim: development of a method for increasing the efficiency of ultrasonic coagulation of particles less than 2,5 microns in size due to emerging vortex acoustic flows in a thin air gap between the emitter and the reflector and a device for its implementation. Results. The authors have proposed a new method and device for cleaning gases from dispersed particles less than 2,5 microns in size by increasing the time of ultrasonic action on each particle and creating zones of local increase in the concentration of fine and submicron particles. This is provided by the formation of vortex flows between the emitting (in the form of a flexural-vibrating disk) and the reflecting surfaces. A local zone of increased concentration of particles is formed in the peripheral region of the vortex, due to the drift of particles under the action of centrifugal particles from the central region of the vortex to its periphery. The proposed method provides the increase in efficiency from 13 to 50 %, depending on the initial concentration of dispersed particles.

The effect of iron carbon agglomerates (ICA) on the reduction of pellet (or sinter) is very important to the smelting efficiency of BF. In this paper, the effect of addition amount of ICA on the re...

Nickel (Ni) nanoparticles (NPs) prepared through vapor-phase synthesis (VPS) are preferred for multilayer ceramic capacitor electrodes due to their high purity and crystallinity advantages. Agglomerated Ni NPs are usually generated using VPS but are undesirable because they cause various problems such as low packing density and electrical shorts. This study proposes the use of coating-assisted chemical vapor synthesis (CVS) for agglomerate inhibition using NaCl or KCl as a coating agent. We have found that the agglomeration ratio, 34.40%, for conventional CVS, can be reduced to 4.80% in the proposed method by in-flight coating with KCl at 900 °C by image analysis using field-emission scanning electron microscopy. Furthermore, the X-ray diffraction and X-ray fluorescence analyses confirm that the NaCl and KCl coating agent can be removed by washing with distilled water. We believe that this coating process can be used to inhibit the formation of agglomerates during the CVS of Ni NPs.

Effective transport coefficient (ETC) of particulate composites is a crucial parameter in many industrial applications. ETC is subject to many microstructural parameters of the system at different scales. In this work, stochastic reconstruction is applied to study possible microstructure configurations between two selected systems. The initial system is configured to a microstructure with overlapping discs agglomerates of monodisperse diameter D = 12 pixels; the final system is configured to a particulate system of monodisperse diameter D = 1 pixel. Easy but powerful diagrams are presented as a quick design tool. The diagram user only requires the determination of two statistical magnitudes: probability of the neighbor connectivity, and infinite cluster, both statistical functions are detailed in the manuscript. This particulate composite information is defined from microstructure images. Proposed diagrams allow the user to get a position in a “map” that describes how ETC magnitude change according to: 1) size of the agglomerate diameter, 2) phase surface fraction, 3) mono-distributed and poly-distributed configuration, and 4) matrix phase or dispersed phase condition as the conductive phase. The diagram user can immediately obtain a full panorama without solving complex equations, which would let to make decisions about the modification of the geometric structure of the particulate composite. The microstructures studied are delimited to biphasic, isotropic particulate composites. The experimental validation of the diagram's effectiveness with particulate composites from the literature is accomplished.

Objective of this work was to develop a novel method for characterizing real 3D shapes of particles smaller than 20 μm by X-ray microtomography (X-RMT). Multidimensional separation of heterogenous solids through agglomeration in suspension will improve recycling processes as the particle shape and the agglomerate size are used for shape-selective separation. In the present paper we discuss the fundamentals of X-ray tomography and the experimental setup for selective spherical agglomeration in suspension. A specific preparation method of the particulate sample for X-RMT followed by 3D image processing, are essential for the shape analysis expressed as sphericity. We also discuss the limitation of this method due to the so-called Partial Volume Effect and particle clusters in the order of magnitude of X-RMT resolution. As proof of concept, we used a mixture of graphite platelets and spheronized graphite particles for a shape selective-agglomeration in suspension. The remaining fines were analyzed and showed more platelets than in the mixture. This indicates that spheronized particles are preferably bound in the agglomerates. These findings show that, based on the discussed sample preparation and a 3D image analysis in connection with X-RMT, particle shapes of micronized particles can be discriminated.

Hydrodynamics of fluidization of hydrophilic titanium nanoparticles with vibration was investigated through pressure fluctuations using recurrence quantification analysis. The bed expansion revealed that the bed operates in the ABF regime. The standard deviation of the pressure fluctuations indicated that vibration reduces the minimum fluidization velocity. Hydrodynamic structures were defined using the wavelet transform analysis of pressure fluctuations and the effect of vibration was investigated through the energy of the pressure signal and the recurrence analysis. It was shown that the agglomerates have the most impact on the fluidization of the nanoparticles and vibration has a significant effect on this structure. Using the energy of the signal and recurrence analysis, characteristics of the vibration on the fluidization were defined. The energy of finer structures is higher in the vibrated bed, indicating a more stochastic pattern in this case. The recurrence rate showed the dynamic behavior of formation and breakage of agglomerates in the bed.