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Ensuring temporal and spatial uniformity in the chamber of a capsule filling machine with vacuum drum is crucial for consistent dosing to in-row capsules. A stirrer must induce axial mixing to maintain a homogeneous powder bed and prevent accumulation in specific regions, primarily caused by the feeding system above the chamber. To achieve satisfactory filling, the performance of different stirrers was analysed using a tracer particle strategy. This contribution introduces a lactose dyeing process, preventing agglomerate formation and yielding minimal differences in powder properties. Four lactose grades, exhibiting diverse particle sizes and flow behaviours, were dyed with methylene blue. A comprehensive analysis of lactose properties, such as particle size, density, and flow behaviour, confirms minimal alterations post-dyeing. Tracers obtained through this process reveal that a spike-type stirrer induces more axial mixing compared to a wire-type stirrer. The dyed lactose tracers effectively contribute to understanding and optimising the capsule filling process. [Display omitted] • Dyeing process for lactose tracers, ensuring minimal property deviation. • In-depth pre/post-dyeing analysis including material characterization and flow properties. • Tracer powder concentration was accurately quantified with UV–Vis spectroscopy. • Study of axial mixing in capsule filling machine using different stirrers. • Dyed lactose obtained can be used to further analyse the capsule filling process. [ABSTRACT FROM AUTHOR]

The average sizes of copper and nickel nano- and microparticles formed at exploding wires in the range of inhomogeneous and homogeneous heating have been established. The average size of nanoparticles grows, and that of microparticles decreases when the value of energy input into wires reaching E ≈ 0,5Es (Es - sublimation energy). While E > 0.5Es the dependence of the average sizes of nano- and microparticles is weakly expressed. The viscosity of feedstocks increases as the proportion of nanoparticles in the powder increases and their size decreases. At equal dispersity and mass content of particles in the polymer, the feedstock viscosity has been found to depend on the adsorption behavior of metals. The analysis of temperature dependence of the feedstock viscosity based on copper and nickel powders has shown that the optimum values of E/Es for one-stage production of micro-nanoparticle powders by the exploding wires lie in the range of 0.4 ... 0.7. [Display omitted] • Оptimum values of E/Es for production of powders lie in the range of 0.4 ... 0.7 • In the region E/Es < 0.5 observed decrease size nanoparticles • Viscosity of feedstock containing 50 vol% copper and nickel at 130 °C equal to 1000–1500 Pa*s. [ABSTRACT FROM AUTHOR]

The Laser Powder Bed Fusion (LPBF) manufacturing of dense Cu parts with near infrared conventional systems is still challenging due to the high reflectivity and thermal conductivity of the powder. In this paper, we investigate a novel approach to improve LPBF processability of Cu through the modification of particle surface properties. Pure Cu powders were coated with a thin layer of high-conductivity Ag by electrodeposition. The coated powder was also heat-treated at 500 °C and 600 °C to promote diffusion at the coating interface, producing different powder particle configurations. LPBF equipped with 200 W laser was used to produce bulk samples using pure Cu and Cu/Ag powder, which were comprehensively characterized by electron microscopy and X-ray diffraction. The Ag coating improved the material processability and density, forming a eutectic phase mixture able to heal pores and defects at the end of the solidification process. [Display omitted] • Cu powder processability enhanced via Ag-coating in low-power near-IR LPBF system • Heat treatment studies on powder to promotes diffusion and heterostructure formation • Notable improvement in material density observed with Ag-coated powders • Healing capability of Ag during last stages of solidification [ABSTRACT FROM AUTHOR]

The study successfully demonstrated an eco-friendly approach for synthesizing mesoporous alumina and mesoporous silica from coal gangue, in line with green chemistry rules. By employing natural breakdown and increased dissolution of coal gangue through specific chemical treatments, along with optimal leaching conditions, this study achieved a dissolution efficiency of over 98% for aluminum. This process, which includes leaching, separation, simultaneous precipitation, selective dissolution, gel formation, and calcination, produced mesoporous alumina and mesoporous silica without the need for templates. The results presented that the synthesized mesoporous alumina and silica had purities of 98.81% and 99.08%, respectively. Additionally, the synthesized mesoporous alumina and silica had specific surface areas of 340.15 and 392.85 m 2 /g, and average pore sizes of 7.27 and 3.25 nm, confirming the desirable physical properties of the synthesized γ-Al 2 O 3 and SiO 2. These products offer a sustainable solution to environmental issues caused by coal accumulation, with promising applications across various industries. [Display omitted] • Eco-friendly production of meso- γ-Al 2 O 3 and meso-SiO 2 powders from coal gangue. • Chemical activation led to the efficient separation of aluminum from silica. • γ-Al 2 O 3 with a purity of 98.81% and a SSA of 340.15 m2/g was obtained. • SiO 2 with a purity of 99.08% and a SSA of 392.85 m2/g was extracted. [ABSTRACT FROM AUTHOR]

Well-defined particle size distributions are required for good flowability and powder packing properties of additive manufacturing powders. Mounting powders within a polymer and using standard metallurgical preparation techniques to cross-section and prepare powder particles for optical analysis allows for simple characterisation processes. However, measured diameters of cross-sectioned particles are typically underestimates of actual particle diameters and hence require stereological correction. The effectiveness of three stereological corrections are investigated in this work, namely the Scheil-Schwartz-Saltykov method, the Goldsmith-Cruz-Orive method and a Finite Difference Method. These methods are investigated against plasma-atomised, gas-atomised and ultrasonically processed Ti-6Al-4V powders. The corrected outputs are compared to laser size diffraction, benchmark data for each powder. Although all three stereological corrections produce improved estimations of the particle size distributions, the Finite Difference Method is recommended producing cumulative mean absolute error values of 2.4%, 3.1% and 7.5% for the plasma-atomised, gas-atomised and ultrasonically processed powders respectively. [Display omitted] • Feedstock particle sizes impact properties of additively manufactured parts. • Polymer-mounted powders result in significant errors for particle size estimation. • Three stereological corrections identified for improved particle size estimation. • A finite difference method of stereological correction is recommended. [ABSTRACT FROM AUTHOR]

The presence of powder agglomerates results in product with poor content uniformity and intermittent high potency in the processing of pharmaceutical powders. We developed a novel and easy-to-implement methodology, applying image analysis, to quantify the size of powder agglomerates when a powder passes through a screw feeder. Subsequently, agglomeration tendencies of twenty-one pharmaceutical powders were examined and classified. Notably, both the size and endurance of agglomerates were quantified, and our study revealed that the agglomeration tendency of powders can be explained by particle size and compressibility: Powders with small particle size (D50 < 30 μm), and large compressibility (> 35% at 15 kPa normal stress) tend to form large and enduring agglomerates, which can be difficult to eliminate in downstream processes. The study also illustrates how two materials, one that produces enduring and the other unenduring agglomerates, display substantially different content uniformity in the final product after being processed semi-continuously. [Display omitted] • A novel methodology to assess powder agglomeration tendency by measuring agglomerates size and endurance after feeder. • Powder agglomeration tendency can be explained by particle size and compressibility. • The large and enduring agglomeration may exist in final product and causing poor content uniformity. [ABSTRACT FROM AUTHOR]

This study focuses on the 316L stainless steel powder produced by using an innovative ultrasonic atomization (UA) method. The production process was optimized at electrical currents with 120 A and vibration amplitude with 80% proving the most effective for maximizing productivity. The study extensively evaluated particle size and shape, bulk and tapped densities, Hausner's ratio, and Carr index, finding the UA steel powder to possess high sphericity, minimal satellite particles, and excellent flowability, qualities crucial for additive manufacturing (AM). A new approach for calculating the additive manufacturing suitability factor was developed, incorporating custom weighting factors for rheological parameters to reduce the influence of parameters with high uncertainty or statistical insignificance, thus improving accuracy. When compared using this method, the UA powder demonstrated superiority over its commercial counterparts by approximately 1% and 10%, underscoring its promise for AM applications. [Display omitted] • A novel method for calculating the additive manufacturing suitability factor was introduced. • Ultrasonically atomized powder outperformed its analogs by approximately 1% and 10%, respectively. • The optimal condition is achieved with a current setting of 120 A. [ABSTRACT FROM AUTHOR]

The die-wall friction is one of the influential mechanical factors in the metal nano-powder compaction process that can noticeably impress the densification behavior of nanoparticles. In this study, the uniaxial cold compaction process of aluminum nano-powders, which are initially loaded into the nickel die-walls, is analyzed using the molecular dynamics (MD) method. The influence of die-wall friction is studied on the nano-powder compaction process. The results illustrate the effect of frictional die-walls on the characteristics of relative density–pressure and stress–strain curves, the pressure distribution of nano-powders, and the final green product. The evolution of the die-wall friction coefficient on the compaction velocity and temperature is determined during the compaction process. Applying the nonlinear regression method, an empirical relation is derived to estimate the frictional behavior of die-walls at different relative densities. It is demonstrated that the proposed computational model has acceptable accuracy to evaluate the die-wall friction during the nano-powder compaction process. [Display omitted] • Influence of die-wall friction on the compaction process of aluminum nano-powders, • Dependence of die-wall friction on the density–pressure and stress–strain curves, • Evolution of friction coefficient at various compaction velocities and temperatures, • An empirical relation for die-wall friction during nano-powder compaction process. [ABSTRACT FROM AUTHOR]

Seed pelletizing can effectively increase the seed size. However, observing the microscopic process of seed pelletizing using physical tests is challenging. This study used the discrete element method (DEM) to simulate the process. Discrete elemental simulation models and contact parameters of seed and powder had been determined by particle scaling theory and parameter calibration tests, respectively. The contact model (modified model) between the seed and powder was established, which could effectively characterize the effect of the water addition on the viscosity. The seed pelletizing numerical simulation test was carried out with the average number of contact particles as the main evaluation index. The results showed that the amount of powder adhering to the surface of individual seeds was 43. Bench test results show that the quality of pelletized seeds met relevant criteria. Discrete element method (DEM) Numerical simulation Seed pelletizing Contact model Repose angle [Display omitted] • Contact parameters of seed and powder were calibrated. • Construct a modified model to characterize the water addition impact. • The process of increasing single seed size by powder adhesion was observed. • Use a new method to evaluate the seed pelletizing simulation test effect. [ABSTRACT FROM AUTHOR]

The Fe6.5Si soft magnetic alloy exhibits promising magnetic properties for energy applications, including near-zero magnetostriction, low magnetocrystalline anisotropy, and higher electrical resistivity than conventional electrical steels. However, its brittleness impedes industrial use. Recent advances in powder-based additive manufacturing show potential for processing high‑silicon electrical steels. This study focuses on the production cycle and properties of feedstock powder, which are crucial for such applications. Fe6.5Si alloy powders were produced via closed-coupled gas atomization. Comprehensive analysis covered mass balance, particle size distribution, powder flow, morphology, density, rheological properties, and thermal and magnetic behavior. Results suggest the feasibility of producing suitable Fe6.5Si alloy powder via gas atomization, enabling additive manufacturing of the next generation of medium/high-frequency electrical motors. The powder exhibited desirable characteristics within the size ranges applicable to laser powder bed fusion (20–75 μm) and direct energy deposition (75–106 μm), showing excellent flow behavior and morphological suitability for additive manufacturing. [Display omitted] • A complete characterization of Fe6.5Si gas-atomized powder was carried out. • Rheological tests demonstrated good flowability and rheological behavior. • The high cooling rates hindered the solid-state ordering of the B2 and D03 phases. • Powder samples did not reach the saturation polarization of bulk Fe6.5Si. • Finer particles possess less favorable magnetic properties compared to larger ones. [ABSTRACT FROM AUTHOR]

Increasing the overall performance of Si-based anodes is still challenging because of the influence of various parameters involved in the preparation processes. This study addresses this challenge by employing the design of experiment technique to assess the impact of ball milling parameters such as milling speed, time, ball to powder and medium to powder ratio on the properties of silicon/graphite (Si/Gr) powders, with a focus on their electrochemical performance. Si/Gr powders in 20:80 weight ratio and 4 factor - 2 level full factorial design were used to find the main effects and interactions. Crystallite sizes were calculated using the Scherrer equation, and span values were obtained from the particle size distribution (PSD) analysis. SEM analyses were carried out to check the microstructure of powders. Ultimately, regression equations were created with high adjusted R 2 values for crystallite size (93%), contamination (92%), and span (91%), respectively. Optimization experiments were carried out using the created regression equations, and the models were verified. It was found that crystallite size obtained by XRD data is more reliable to assess powder properties on the performance instead of PSD because of the agglomeration at the particle level throughout the milling. Further milling experiments were performed to elaborate the role of oxygen content and crystallite size. Results showed that while initial capacity is strongly related to total oxygen content, decay in the first cycles is correlated to the crystallite size of the silicon powder. [Display omitted] • Design of experiment is an effective way to investigate the milling parameters. • Equations were created with high adjusted R 2 values for crystallite size, span and contamination. • Total oxygen content of Si/Gr anode determines initial discharge capacity. • Smaller Si crystallite size provides better stability. [ABSTRACT FROM AUTHOR]

This study presents a methodology for determining powder systems' Critical Binder Volume Concentration (CBVC), a key parameter in optimizing paste properties for various shaping processes. Leveraging both press and pycnometer density measurements, our approach precisely identifies the CBVC by analysing the pressure-dependency of powder compaction within a confined cavity, reflecting the interplay between internal friction and packing capacity. Through comparative analysis with established techniques, we validate our method using a nano-sized WC-Co powder system combined with two distinct organic binders, linseed oil and a proprietary binder. The method finds the maximum packing fraction more efficiently and utilizes less material than conventional CBVC determination techniques. A zero-pressure density is introduced and its applicability to other powder types, including ceramics and metals, is anticipated. [Display omitted] • New Methodology for Critical Binder Volume Content (CBVC) determination of powders. • The proposed method yields the lowest CBVC values compared to existing techniques. • Introduction of a quantity called the zero-pressure density (ρ P 0) and CBVC P 0. • The method is validated for nano-sized WC-Co hard metal powders. • Results suggest the applicability to other powder systems like ceramics and metals. [ABSTRACT FROM AUTHOR]

Spreading of fine (D50 ≤ 20 μ m) powders into thin layers, such as required by layer-wise additive manufacturing (AM) processes, typically requires a mechanism such as a roller that provides adequate shear and compression to overcome the cohesive forces between particles. We explore improved, roller-based spreading strategies for highly cohesive powders using an integrated discrete element-finite element (DEM-FEM) framework. We find that optimal roller-based spreading, quantified by maximum packing density and uniformity of layer thickness, relies on a combination of surface friction of the roller and roller kinematics, e.g. , counter-rotation or angular oscillation, that impart sufficient kinetic energy to break cohesive bonds between powder particles. However, excess rotation speed (or shear stress) can impart excessive kinetic energy to the powder causing ejection of particles and a non-uniform layer, suggesting the existence of a process window of optimal spreading parameters. Interestingly, the identified optimal parameters for both investigated roller kinematics, i.e. , angular velocity for counter-rotation as well as angular frequency and amplitude for rotational oscillation, result in a very similar range of roller surface velocities, suggesting roller surface velocity as the critical kinematic parameter. When these conditions are chosen appropriately, layers with packing fractions beyond 50% are predicted for layer thicknesses as small as ∼ 2 times D90 of the exemplary cohesive powder, and the layer quality is robust with respect to substrate adhesion over a 10-fold range. The latter is an important consideration given the spatially varying substrate conditions in AM due to the combination of fused/bound and bare powder regions. As compared to counter-rotation, the proposed rotational oscillation kinematics are particularly attractive because they can overcome practical issues with mechanical runout of roller mechanisms (which limit their precision). [Display omitted] • DEM-FEM framework is used to model powder spreading incl. with rubber-coated rollers. • Dense, consistent, and thin powder layers are achieved with highly cohesive powders. • Optimal counter-rotation and angular oscillation yields similar surface velocities. • Amount of shear needs to balance breaking cohesive bonds with not ejecting particles. • Optimal spreading parameters robust to changing substrate conditions. [ABSTRACT FROM AUTHOR]

Laser Powder Bed Fusion (L-PBF) is an important route for processing aluminum alloys, nevertheless, the high laser reflectivity and thermal conductivity and lower powder flowability of the aluminum alloys remain a challenge for their processing. Aiming to overcome these issues, AA2017 powders were surface-functionalized using chemical etchings. The powders' physical and rheological characterization revealed a decrease in the laser reflectance and an improvement in the flowability of the surface-functionalized powders, when compared to the gas-atomized powder. The higher amount of keyhole porosity in the as-printed L-PBF samples using the surface-functionalized powders also suggests an improvement in the laser absorption of these powders. However, the formation of a thick oxide layer on the surface-functionalized powders led to oxidation porosity in the as-printed samples. Therefore, the chemical etching should be improved to avoid the formation of a thick oxide layer on the powder surface and oxidation porosity in the as-printed L-PBF samples. [Display omitted] • Surface functionalization of aluminum powders for L-PBF using chemical etchings. • Improved flowability and laser absorption of the surface-functionalized powders. • Better L-PBF suitability of the surface-functionalized powders. • Formation of keyhole and oxidation porosities in the as-printed L-PBF samples. [ABSTRACT FROM AUTHOR]

The rational movement and distribution of the powder phase play a significant role in promoting energy efficiency and low carbon emissions in blast furnace (BF) ironmaking. Precise description of the shape of ore is vital for simulating the solid phase motion in a BF. In this study, the shapes of actual particles were captured using a highly accurate 3D scanner, followed by a comparison of the geometric shape characterization of the regular and real particles. A detailed analysis was conducted on the characteristics of the packed bed formed by particles of various shapes and the movement process of the powder phase within the packed bed by using discrete element method (DEM). The distribution and hold-up of the powder phase in the polyhedral and spherical-polyhedral packed beds closely resembles that in the real packed bed. Given the computational time and simulation accuracy, polyhedral or spherical-polyhedral particles could potentially replace the spherical particles typically used in packed beds. This substitution is particularly relevant for applying the DEM to large-scale BF simulations. [Display omitted] • The shape of the particle was obtained through high-precision 3D scanning. • Polyhedral-based particle are suitable for simulating the motion of real particle. • The motion of powder phases in regular and real particle-filled beds studied. • Polyhedron-based particles could be used instead of real particles to generate coke beds. [ABSTRACT FROM AUTHOR]

The growing demand for a reliable supply of minerals has pushed the European Union toward seeking novel mineral sources. In the present work, the recovery of magnesium, in the form of magnesium hydroxide, Mg(OH) 2 , from saltworks bitterns was investigated at a pilot scale. The natural bittern collected from Margi saltworks (Trapani, Italy) was treated with synthetic sodium hydroxide (NaOH) solutions. The influence of different reactant concentrations, flow rates and pH environments, on Mg(OH) 2 particle sizes, filtration characteristics, Mg2+ extraction performance and the Mg(OH) 2 solid purity was thoroughly assessed. The presence of additional dissolved salts in NaOH solutions was also analyzed. The pH environment was found to be the most crucial parameter. On the one hand, high pH values ensured high Mg2+ recovery and powder purities, i.e. > 98%, with boron content complying with market requirements. On the other hand, filtration characteristics considerably worsened due to the lyosorption phenomenon. [Display omitted] • Mg(OH) 2 powders produced by using a pilot scale reactor were characterized. • Real saltworks bitterns, by-products of sea salt production, were exploited. • The reaction pH was the crucial parameter for powder purity and filtration. • High pH ensured high Mg2+ recovery and purities, but long filtration times. [ABSTRACT FROM AUTHOR]

The surface quality issue of the laser powder bed fused (LPBF-ed) parts deteriorates the mechanical properties. Laser beam defocusing (LBD) can effectively improve the surface quality. To reveal the effect mechanism of LBD on the surface quality of the LPBF-ed parts, a laser powder bed fusion (LPBF) numerical model is established. Based on the calculated results, the formation process of the surface defects such as bulges, depressions, partially melted powders and spatters and the corresponding melt pool dynamic behaviors are investigated. The effects of LBD on the melt pool dynamic behaviors during the surface defects formation and the track width are discussed. The results show that LBD can improve the surface quality by reducing Marangoni force and recoil pressure to reduce bulge height and depression depth, increasing track width to decrease partially melted powders, and increasing surface tension and reducing kinetic energy to decrease spatters. [Display omitted] • A LPBF numerical model is established for investigating the effect of laser beam defocusing. • The laser's beam divergence is considered in the heat source. • The effect of laser beam defocusing on the melt pool dynamic behaviors is discussed. • The effect mechanism of laser beam defocusing on the surface quality of the LPBF-ed parts is revealed. [ABSTRACT FROM AUTHOR]

The dynamics of cohesive particles and their tendency to adhere to surfaces present significant challenges in various industrial processes. A profound understanding of adhesive and cohesive forces is crucial for the optimized design of continuous manufacturing systems, aiming to effectively mitigate flow-related issues such as blockages, segregation, irregular flow patterns, and flooding. In this study, the adhesive forces of eight excipients using four distinct methodologies were systematically evaluated, i.e., colloidal atomic force microscopy, contact angle measurement, drop tester, and centrifugation for comparative analysis. Qualitative assessments of cohesion, including the angle of repose, rotating drum, Carr index, and Hausner ratio were additionally implemented to corroborate the findings. By evaluating these methodologies in conjunction, the strengths and limitations of each approach can be explored. This comparison paves the way for a more nuanced understanding of particle adhesion dynamics and can aid in selecting the most suitable technique for specific applications. [Display omitted] • Four distinct particle-scale adhesion measurement techniques were quantitatively compared. • Particle-scale adhesion measurement were assessed against bulk scale cohesion characterization of eight excipients. • The strengths and limitations of each technique were evaluated, which aids in process design. • Colloid-AFM offers detailed insights into particle-scale adhesion, cohesion, surface roughness, and mechanical properties. [ABSTRACT FROM AUTHOR]

This work investigates the impact of changes in the moisture content of bulk materials. The regularity of moisture change in bulk materials was evaluated for three different particle size classes of clay powders. The research measures the angle of internal friction and flowability under four different normal loads, reflecting the varying pressures during bulk material storage. The influence of moisture change in bulk materials was most pronounced for the smallest particle size fraction, where even a very small moisture change in the order of tenths of a percent steeply affected flowability due to internal friction. After increasing the moisture content by a few percent, a steady state of flow occurred. Critical value was determined when water in the bulk material caused liquefaction. For larger particle size fractions, the impact of moisture change was evident only at higher values (12.5%), with no liquefaction occurring even at 30% moisture. The change in normal load, on the other hand, affected particles of larger size fractions, resulting in improved flow properties. [Display omitted] • The fine clay fraction 0–0.5 mm is extremely sensitive to changes in moisture • The change in fine clay moisture content showed an AIFE variance of up to 20° • The liquefaction and effect on clay internal friction and flowability were determined • Internal friction of fine clay is explained using regression model • As clay powders moisture increases the effect of normal load on AIFE [ABSTRACT FROM AUTHOR]

We report the improved soft magnetic properties of FeSi powder core (PC) by doping an appropriate amount of fine FeSiCrBC amorphous powder into the air gaps between the triple-junction structures of coarse FeSi powder. Resultantly, the addition of FeSiCrBC powder, which has a lower permeability (μ e) and higher hardness relative to FeSi powder, does not lead to a decrease in the μ e of the FeSi/FeSiCrBC compound PC (CPC) with the reduced porosity but rather yields an increase. Rationally, this is attributed to the enhanced magnetic coupling in the CPC, which is compared with the corresponding ones with FeSi or FeSiAl PCs. Meanwhile, the core loss of the CPC reduces significantly. This is due to the decreased non-uniform magnetization regions in the CPC with proper content FeSiCrBC addition. The results herein can provide a novel strategy for fabricating PCs used in new-generation high-properties and miniaturized inductors. [Display omitted] • Fine FeSiCrBC powder easily fills gaps within FeSi powder core. • Adding FeSiCrBC can increase the permeability in FeSi powder core. • Adding FeSiCrBC can reduced the core losses of FeSi powder core. • The FeSiCrBC enhances the triple-junction structure magnetic coupling. [ABSTRACT FROM AUTHOR]

Magnesium hydroxide silicate (MSH), as an antiwear additive for lubricating oil, effectively solves the problem that conventional additives contain chlorine, phosphorus and sulfur, which are harmful to environment. However, it is ineffective to prepare MSH powder by traditional drying combined with mechanical ball milling. So the purpose of this study is to prepare smooth MSH microspheres with controllable particle size and moisture content by adjusting spray drying parameters based on hydrothermal synthetic MSH suspension. Results showed that the particle size of MSH microsphere was reduced from 5.5 ± 2.9 μm to 2.78 ± 1.37 μm, and the moisture content was reduced from 7.3% to 4.43% by decreasing solid-liquid ratios and rotating speed of peristaltic pump, or raising inlet temperature of hot air, flow rate of compressed gas and inlet air. In addition, due to the surface energy difference at the interface between liquid-gas and solid-gas during the drying process, nano flaky MSH continuously moved to the center of the droplet, and the capillary force generated by gaps between MSH nanosheets discharges the moisture in the wet core, so that the MSH nanosheets gather and finally form dense and smooth MSH microspheres. [Display omitted] • The magnesium silicate hydroxide suspension was dried by spray drying technique. • Particle shape and size can be effectively controlled by adjusting drying parameters. • MSH microspheres with dense structures were created by nano flake MSH. • The key factor affecting moisture content is the match of inlet temperature and flow rate. [ABSTRACT FROM AUTHOR]

The freze-dried colostrum powders were agglomerated with different binders (distilled water, lactose, maltodextrin and sucrose) and the highest agglomeration efficiency (62.65%) belonged to the process in which the sucrose binder was used. The agglomeration process significantly increased the particle size of all powders, and the highest particle size (365.67 μm) belonged to the agglomerated powder with lactose binder. The agglomeration process improved the fluidity properties of colostrum powder (by reducing CI, HR and AOR values), especially in colostrum powders agglomerated with distilled water. As a result of the agglomeration process in which maltodextrin and sucrose were used as binders, the reconstitution properties of the samples improved significantly with 83.23% and 82.7% solubility ratio, respectively compared to the freeze-dried control colostrum powder. According to DSC thermogram, the thermal resistance of agglomerated colostrum powders increased. As a result agglomerated colostrum powder with improved instant properties was obtained. [Display omitted] • Colostrum milk was transformed into powder form using spray dryer and freze dryer. • Freeze-dried colostrum powder was agglomerated with different binders. • The spray-dried powder could not be agglomerated because not forming a fluid bed. • The fluidity and reconstitution properties of colostrum powder were improved. • Instant colostrum powder was obtained thanks to the agglomeration process. [ABSTRACT FROM AUTHOR]

Exploring the application of slag in methane explosion suppression can contribute to its waste resource utilization. In this study, waste slag was subjected to high-temperature scorching and modified using the sol-gel method. Subsequently, a mechanochemical technology was employed to create a composite powder consisting of KHCO 3 and modified slag. A 20 L explosion ball was also used to assess the features of explosion suppression, and pyrolysis characteristics and explosion products were analyzed to clarify the underlying mechanism. The best explosion suppression was shown by adding 0.1 g/L 40 wt% of KHCO 3 /modified slag composite powder. It reduced P max and (d P /d t) max by 42.35% and 89.47%, respectively, while extending the time for the flame to reach the edge of the transparent window by a factor of 7.1 in 9.5% methane explosion. The KHCO 3 /modified slag composite powder efficiently suppresses explosions by absorbing heat, creating barriers, and adsorbing and consuming free radicals. [Display omitted] • Waste slag, possesses great potential for resourcing transformed into explosion suppressant. • Superfine KHCO 3 /modified slag composite explosion suppressant is prepared by a mechanochemical technology. • Modified slag improves the dispersion of KHCO 3. • KHCO 3 /modified slag composite powder has a significant effect on reducing the relevant explosion parameters. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), epitomized by powder bed fusion (PBF), has emerged as one of the fastest-growing, most dynamic, and highly focused techniques within the advanced manufacturing sector. Nevertheless, as the primary factor determining cost and quality of PBF-produced parts, amounts of metal powder feedstock remains unused and requires recycling after each PBF build. Due to the unique thermal history experienced by individual particles during manufacturing, recycled powders exhibit variations in chemical composition, particle morphology, size, size distribution, microstructure, and even thermal-physical properties. Moreover, these alterations are influenced by the inherent properties of the metal powder, machine setup, and manufacturing process. Consequently, the repeatability and reproducibility of the recycled powders cannot be defined uniformly. Using Ti6Al4V, Inconel 718, AlSi10Mg, and stainless steel metal powders as examples, this paper reviews recent literature specifically addressing recyclability and reusability of the recycled powders, in particular the subsequent effects of the reused powder on powder beds, process operation, and product properties in PBF builds. By exploring the interaction between energy beam, powder and melt pool, we discuss the formation mechanism and composition of the recycled powders, and analyze the impact of powder building cycles and varying powder characteristics on powder bed properties, manufacturing processes, part microstructures, and mechanical properties. Additionally, we discuss the solutions for identifying end-of-life powder and introduce strategies to enhance powder reusability. In doing so, we seek to provide a comprehensive understanding of powder feedstock for building an optimized processing window, with a view to contributing to extending the service life of metal powders. Recycled powders exhibit variations in chemical composition, particle morphology, size, size distribution, microstructure, etc. By exploring the interaction between the energy beam, powder and melt pool, this paper discuss the formation mechanism and composition of the recycled powders. Furthermore, the impact of reused powder on powder bed properties, manufacturing processes, part microstructures, and mechanical properties are analyzed. Additionally, the solutions for identifying end-of-life powder and strategies to enhance powder reusability are introduced. [Display omitted] • The stronger interaction results in the characteristics changes of recycled powder. • Understanding thermal history of the powder is helpful for powder characterization. • Timely tuning of process parameters is useful to powder recycling and part quality. [ABSTRACT FROM AUTHOR]

The National Institute of Standards and Technology (NIST) organized an interlaboratory study to assess the repeatability and reproducibility of the data generated by two commercially available rotating drum powder rheometers namely, Granudrum and Revolution Powder Analyzer. Part 1 of this interlaboratory study focuses on the Granudrum rheometer. In total, thirteen laboratories comprised of industry, academia, and a national laboratory participated in this study. A nickel-based alloy, a titanium alloy, and a stainless-steel alloy in powder forms were tested, and an analysis of variance (ANOVA) model was used to rank the contributions of the study factors to the observed variability in the data. First, a maximum of five study factors were considered: material, sample, rotation speed, test, and participant (lab), which provides the ability to assess interactions, such as between lab and rotation speed and lab and material. The ANOVA results indicate that the 'Flow Angle' data showed 6% of its variation attributable to repeatability and 5% to reproducibility, whereas the 'Cohesive Index' data showed 21% of its variation attributable to repeatability and 17% to reproducibility. Next, because using the different rotation speeds and materials can add significant variability to the overall data, we also present separate ANOVA results for each combination of rotation speed and material. These results provide further insight into the repeatability and reproducibility of the Granudrum-generated data. [Display omitted] • NIST organized an interlaboratory study to assess rotating drum powder rheometers. • Part 1 of this interlaboratory study focuses on the Granudrum powder rheometer. • Thirteen laboratories, comprised of industry, academia, and NIST were involved. • Three alloys (nickel, titanium, and stainless steel) in powder forms were tested. • Repeatability and reproducibility of the measurements were analyzed. [ABSTRACT FROM AUTHOR]

Low retention of bioactive compounds caused by high stickiness associated with sugar-rich fluids are of concern in the industrial production of spray-dried fruit powders. An alternative is spray-freeze-drying SFD, which operates under low temperatures but subsequent handling can be impacted by high hygroscopicity. This study explores the use of bulking (maltose and maltodextrin) and wall materials (hydroxypropyl methylcellulose HPMC and whey protein) to encapsulate strawberry, mango, and orange juices. SFD showed the highest spraying yields, on average 85%. Stickiness showed significant changes (p < 0.05) among encapsulated and non-encapsulated powders. HPMC encapsulation improved SFD fruit powder by lower moisture uptake (on average 2%). Encapsulation obtained by whey protein and by HPMC resulted in the lowest adhesion forces between powders, around 40 g, and in the lowest mold spore count, 25 per area, in powders exposed at room temperature for two months. [Display omitted] • Spray freeze dried powders has at least 20% higher yield. • Whey as coating agent produces the lowest adhesion forces (40 ± 5 g). • Highest total phenolic content are obtained when maltose is the bulking agent. • HPMC as coating agent produces the lowest mold counts per area (12 ± 4). [ABSTRACT FROM AUTHOR]

The mechanical pretreatment of a powder mixture of niobium and silicon was studied experimentally and theoretically using the new macrokinetic theory of mechanochemical synthesis. The method of organizing the operation mode of the ball mill affects the degree of grinding and activation of the powder composition, as well as the rate of formation of intermediate phases. The effect of cycling on the temperature inside the mill drum, particle size of the powder mixture, formation of mechanically synthesized niobium silicides, and structure of the initial components has been studied. Varying the cycling can lead to safe and emergency operation of the mill. The final mixtures' characteristics may vary significantly depending on the number of cycles of discontinuous mechanical treatment, even if the total operating time of the ball mill remains the same. The safe conditions for cyclic operation of the mill were determined. The effects of different mechanical treatment modes on the grinding, activation, and phase formation of a powder mixture were investigated. Various parameters were analyzed, including thermophysical, physico-chemical, and kinetic characteristics of the cyclic operation of the AGO-3 ball mill, the kinetics of grinding and activation of Nb and Si particles, and the rate of mechanochemical reaction in the mechanically activated mixture of Nb + 2Si. [Display omitted] • Safe or emergency mode depends on the cycle of ball milling. • Different ball milling cycles lead to different characteristics of the Nb + 2Si mixture. • Thermophysical, kinetic constants determined for the mixture of Nb + 2Si ball milling. [ABSTRACT FROM AUTHOR]

Reactive powder concrete (RPC) stands as an ultra-high-performance concrete (UHPC), widely acknowledged for its exceptional strength and durability. However, the high carbon footprint of RPC is a concern due to its substantial reliance on Portland cement. The development of alkali-activated binder reactive powder concrete (AAB-RPC) offers a potential alternative, seeking not only to enhance durability but also to promote sustainability. Despite this, a comprehensive solution to the optimized design of AAB-RPC is currently unavailable. While the packing density method, a physics-based mix design approach, has been proven effective in Portland cement-based RPC, its applicability and extensibility to AAB-RPC system remain unexplored. This study aims to optimize the strength design of AAB-RPC by using the packing density method. It employs modified continuous packing particle models to design various AAB-RPC mixtures, utilizing distribution modulus q and liquid-to-solid volume ratio as design variables. The selection of optimal mix proportions is based on packing density and workability, followed by the analysis of compressive strength at different ages. The results show that the maximum strength of AAB-RPC occurs when q value ranges from 0.25 to 0.30. Furthermore, a positive correlation is observed between wet packing density and compressive strength. Additionally, a strength formula for AAB-RPC, grounded in q value, maximum packing density, and age, achieved an impressive coefficient of determination (R2) of 0.938. The results demonstrate the efficacy and reliability of the wet packing density method in AAB-RPC mixture design. [Display omitted] • Strength of AAB-RPC is optimized based on concept of wet packing density. • Strength of AAB-RPC is influenced by wet packing density and distribution modulus. • A formula is proposed to estimate the time-dependent strength of AAB-RPC. [ABSTRACT FROM AUTHOR]

The incorporation of natural ingredients to food products as a source of bioactive compounds is currently an increasing trend for food companies. The purposes of this work were to study the physicochemical properties of microencapsulated propolis powder, and to research the potential beneficial effect of it on texture and sensory quality of sugar-free chewing gums. Propolis ethanolic extract was microencapsulated by spray-drying technology, using maltodextrin as carrier, protecting conceivable bioactivity. Morphology of propolis microparticles was evaluated using Scanning Electron Microscope (SEM) and showed homogeneous microparticles with different sizes and no cracks. Propolis powder showed low water activity, moisture and hygroscopicity, high amounts of Ca, P, and high values for antioxidant-related parameters. Propolis powder phenolics were analysed by HPLC-UV and HPLC-ESI-MS. Apigenin, gallic acid, CAPE, and galangin demonstrated the highest degree of encapsulation, providing antiradical activities. Propolis powder was incorporated in chewing gums at 5%, improving their texture and sensory properties. [Display omitted] • Spray drying encapsulation shows good retention of bioactive compounds. • Phenolics of microencapsulated propolis powder are identified. • Microencapsulated propolis powder has homogeneous surface without cracked walls. • Propolis powder improves texture and sensory properties of chewing gum. • Microencapsulated propolis powder can be used as functional food ingredient. [ABSTRACT FROM AUTHOR]

Properties of explosion suppression material have a significant impact on controlling the explosion propagations. Bentonite, with a large surface area and abundant pore structure, can adsorb free radicals during the explosion reactions. It is a kind of ideal explosion suppression materials. However, bentonite can easily absorb moisture and solidify into cakes in a humid environment, which lacks the possibilities of reactions with radicals in explosions and results in a poor suppression effect. To enhance the space suspension property of bentonite, in this paper, three surface modification methods are proposed to prepare the modified bentonite-based powder by using a silane coupling agent modification, silica encapsulation modification, and quaternary ammonium salt insertion modification. Then, changes in the characteristics of modified bentonite are analyzed and characterized using FTIR, SEM, et al. The results show that the pore structures fundamentally changed and surface is poor combination with water, which greatly solves the "Caking" problem. [Display omitted] • Modified powders maintain excellent explosion suppression in wet environments. • Surface modification, encapsulation modification, insertion modification. • Characterization: particle size, infrared, morphology, DSC-TGA, etc. • Mechanism: inhibition of explosion in the free radical evolution characterization. [ABSTRACT FROM AUTHOR]

This study employs the DEM to simulate powder flow in the Fette-1200i tablet press three-chambered feed-frame system under varying operating conditions. It examines the influence of operational speeds on parameters like residence time, particle travel distance, shear work, paddle torque, tablet weight, and API concentration. Utilizing continuous spatial surface maps, the research comprehensively analyzes powder flow behavior. Results indicate that particle residence time increases with paddle speed but decreases with turret speed. Similar trends are observed for particle travel distance and shear work. Larger particle residence time can lead to overlubrication. The torque of the paddles is related to the volume of material in each chamber, with the distributing chamber having the largest volume. Tablet weight rises with paddle speed but drops with turret speed. The smallest particle (API) tends to collect near the paddle hub due to limited centrifugal force and on the chamber floor due to percolation. However, the tablet's API content eventually stabilizes at the target concentration. [Display omitted] • DEM simulations of a three-chambered feed frame were performed. • Spatial maps of residence time, API distribution, etc. provide a comprehensive understanding. • Powder flows preferentially at the hopper-feeder interface. • Residence time plays a major role in API distribution and particle attrition. • Tablet quality was evaluated based on weight variability and API content uniformity. [ABSTRACT FROM AUTHOR]

The particle size distribution (PSD) significantly influences the flow and fluidization behaviors of powders, with the left section of PSD, indicating the portion of smaller particles, exerting dominant effects. Limited research has focused on exploring the impact of the left section of PSD on powder characteristics. Therefore, three types of Group C cohesive powders with the same diameter (20 μm) but different PSDs are derived from the same material. Results demonstrate that more abundant superfine components lead to diminished flow and fluidization quality. Finer particles exhibit greater potential for retaining gas within the bed, while realizing this potential requires specific auxiliary techniques (nanoparticle modulation), to reduce powder cohesiveness. A new parameter, termed "Left Span", is proposed to depict the left portion of PSD. Sensitivity analysis reveals that flow and fluidization properties are more responsive to "Left Span" compared to span, which encompasses both the left and right sections of PSD. [Display omitted] • The left section of PSD strongly impacts cohesive particle flow and fluidization. • More superfine components lead to reduced flow and fluidization quality of powders. • A new parameter, "Left Span", can be used to depict the left portion of PSD. • Powder properties are more responsive to "Left Span" compared to span. [ABSTRACT FROM AUTHOR]

Manipulation of the pore defects, adjustments of α/β phases fractions, optimization of the mechanical properties are helpful for sintered Ti6Al4V alloys fabricated Metal injection molding (MIM) powders. A pseudo quasi in-situ method with vacuum encapsulation and quenching has been proposed to control dynamical characteristics of pores, grain sizes and phase fractions of MIMed Ti6Al4V powders during sintering process. The dependency of pores annihilation and grains growth on sintering time and temperature has been established. Higher sintering temperature shortens the transition period of pore morphology from connected irregular to enclosed spherical characteristics. The annihilation of pores satisfies the exponential function as well as the power law with temperature and time, respectively. The activation energy has been calculated to be 252.2 kJ/mol comparable to self-diffusion activation energy of Ti according to Arrhenius fitting of the changes of grain size with sintering temperature. Additionally, the diffusional kinetic coefficient was 28.57 at 1200 °C, about five times larger than that at 1100 °C. The fraction of α/α′ phase decreases with increasing of sintering temperature and time. The existence of impurity elements (O, C) may result increasing the stability of α phases and morphology transforming of α phases from lamellar to equiaxed. Finally, sintered MIM-ed Ti6Al4V alloys with lowest porosity sintered at 1200 °C for 4 h have the tensile strength of 922 ± 5 MPa, the yield stress of 833 ± 4 MPa and the elongation of 12.8 ± 0.5%. [Display omitted] • Microstructure evolution of MIM-TC4 in real-time sintering process was studied. • A novel pseudo quasi in-situ method was proposed. • Relation was established between sintering parameters and microstructure features. • The microstructure was identified that was in favor of mechanical behavior. [ABSTRACT FROM AUTHOR]

We find some mistakes in the operating conditions or the parameter units of Table 1 and some figures of our article published in Powder Technology. (Wang Shuai, Li Xiang, Lu Huilin⁎, Liu Guodong, Wang Jiaxing, Xu Pengfei. Simulation of cohesive particle motion in a sound-assisted fluidized bed, Powder Technology 207 (2011) 65–77). Thus, we send a corrigendum for correction. If need more requirements, please let me know as soon as possible. • Some mistakes in our article published in Powder Technology 207 (2011) 65–77. [ABSTRACT FROM AUTHOR]

The adoption of the Laser Powder Bed Fusion (LPBF) process faces challenges due to a low productivity and high powder costs. Improvements in productivity can be achieved by increasing the laser power and the layer thickness. The present work explores an alternative approach by investigating the use of coarser particle size distributions in conjunction with thick powder layers. This approach potentially allows the valorisation of currently unexploited powder fractions in the LPBF process. In this work, blends of AISI 420 stainless steel powders are characterised in terms of their compaction dynamics and flow properties. The results obtained show that different levels of cohesion and compaction rate are found depending on the size ratio, the absolute size of the fine powder and its fraction. This work provides guidance for the selection of powder blends and opens up the possibility of their use in the LPBF process. [Display omitted] • Powder blends with coarse powder do not significantly degrade flowability. • Flow properties of the powder blends can be adjusted with the fine powder fraction. • Powder blends composed of coarse powders improve the compaction rate. [ABSTRACT FROM AUTHOR]

This work investigates the link between the single particle and bulk flow properties of stainless steel (SS316L) powders and their spreading behaviour for additive manufacturing (AM) application. Two different batches of SS316L powders, noted to have significantly different spreading behaviour in AM machines, were investigated. The two batches had almost identical particle size, morphology and bulk flow properties as quantified by angle of repose, Hausner ratio, Carr index and basic flow energy; however one of the batches did not consistently flow during Hall and Carney flow tests and also had very poor spreadability when evaluated using an in-house spreading rig. The flow and spreading behaviours of the poorly spreading batch significantly improved and became almost identical to the good batch when tested following drying, either in a vacuum oven or a freeze dryer. Elemental analysis revealed that batches had some small but significant differences in chemical composition. This study revealed the complexity of defining a correlation between powder properties and spreading behaviour, and the importance of considering the environmental conditions. [Display omitted] • Flowability and spreadability of two grades of SS316L powders were characterised. • The powders have vastly different spreadability despite very similar particle characteristics. • The poorly spreading powder had less carbon but higher Cr contents than the other batch. • Humidity negatively affected the spreading behaviour of SS316L powders with less carbon. • The spreading behaviour could only be related to Hall and Carney flow measurements. [ABSTRACT FROM AUTHOR]

Accurate prediction of flow mode in pneumatic conveying can be beneficial for design of a reliable pneumatic conveying system. The existing popular powder classification diagrams use particle or loose poured bulk density and average particle diameter. An evaluation carried out with powder characterization and conveying data of 58 powders reveals that all the existing classification diagrams have some overlapping zones between fluidized dense- and dilute-phase. Such uncertainty significantly limits the use of existing classification diagrams. A new classification diagram has been developed using the powder characterization and conveying data of 58 powders for fluidized dense to dilute-phase regime using a modified particle Froude number term (based on loose poured bulk density) and particle size distribution. The novelty of this classification diagram is that it uses coarse to fine ratio (instead of average particle size) and a loose poured bulk density based Froude number term which uses both loose poured bulk density and median size. Hence, the classification diagram considers larger number of particle and bulk properties: loose poured bulk density and different particle size terms (such as d 10 , d 50 , d 90 , instead of only d 50). The new characterization diagram quantitatively marks an uncertain zone in the classification diagram, which in the zone the powders can be transported in either dense-phase or dilute-phase, as there is no certainty on the expected nature of flow for powders falling in these zones and hence these powders must be tested in a pilot plant for conveyability. [Display omitted] • A new characterization diagram for mode of flow is developed. • The characterization diagram was updated to include new dimensionless parameters. • Dimensionless parameters used coarse to fine ratio and modified particle froude no. • Included is a thorough examination of well-known characterization diagrams. • For defining precise boundaries in the diagram data from other studies was included. [ABSTRACT FROM AUTHOR]

Dense and uniform initial packing structures of powders are of key significance in powder metallurgy process, which can provide the precondition for the fabrication of high-performance components with low cost and high efficiency. In this paper, the packing densification of indium tin oxide (ITO) granulated micro powders with continuous size distributions and internal porosity under three-dimensional vibrations was numerically investigated by discrete element method (DEM). Firstly, the DEM model was validated by physical experiments, and the contact parameters between particles and the porosity therein were determined. Then the effects of operating parameters on the macro/micro properties (e.g., packing density, coordination number (CN), pores, and forces) of the packing structures were analyzed. Results show that the mean CN cannot intuitively reflect the packing structure due to the complex and varied inter-particle contacts caused by the inhomogeneity of the particle size in a multi-sized granular system. Additionally, the excellent packing structure of porous ITO particles is always obtained from low amplitude when the vibration intensity is the same. Corresponding mechanism analyses reveal that higher amplitude normally causes strong convective diffusion, leading to more pores in the packing. This increases the probability of wedging effect occurring during settling, thereby reducing the packing density. However, optimal packing quality with low amplitude can only be achieved when coupled with high frequency. Therefore, applying vibration is an effective way to achieve dense packing of porous spherical particles, especially at low amplitude and high-frequency operating conditions. [Display omitted] • Vibrated packing densification of granulated ITO powders is numerically studied. • A revised method to calculate the packing density of porous powder is developed. • Various macro−/microscopic properties of packings are quantitatively characterized. • A new strategy for process optimization and design is proposed. • Densification mechanisms are analyzed through convective diffusion/local clusters. [ABSTRACT FROM AUTHOR]

In this work, the effect of powder ball milling pretreatment on the microstructure and properties of the Mo-30W-20Cu (mass fraction) refractory functional alloys sintered in normal-pressure H 2 is investigated systematically. The results indicate that a moderate milling can obviously refine the particle size of the Mo-30W-20Cu composite powder, largely contributing to the sintering densification and thermo-physical property improvement. In contrast, an excess milling instead causes reaggregation of plastic Cu particles, negatively influencing the following compact densification and the property improvement. The composition analysis shows that there is a strong compositional inheritance correlation between the pretreated powders and the corresponding bulk alloys. Besides, the experimental and the calculated results of the thermal and electrical conductivities of the sintered alloys are compared, and they show a similar trend with milling time varying. This work can provide valuable theoretical and technological insights for preparation of high-performance Mo-W-Cu refractory functional alloys. [Display omitted] • The effective refinement of powder particles requires a moderate ball milling. • A solution inheritance exists in the pretreated powders and the sintered alloys. • When the milling time is 10 h, the optimum comprehensive properties are obtained. • The calculated and the measured values of Mo-W-Cu properties show a similar change trend. [ABSTRACT FROM AUTHOR]

The aim of the paper is to propose the development of a MEX feedstock composed of a bio-sourced binder and a tool steel powder to be printed with a pellet printer. A bio-based feedstock with the highest powder load is made using different powder sizes. It is shaped into test samples with Fused Granulate Fabrication process, from where the polymer binder is then eliminated by thermal degradation. The resulting powder skeleton is densified by conventional sintering, to achieve a maximal density. The densified samples are examined by X-ray tomography for the evaluation of their internal porosity. The developed method permits to get, from optimised stages, final components with a high density of 97%, equivalent to that obtained using conventional PIM processes, with a dimensional shrinkage of 13%. The physicochemical composition of the densified components obtained is in line with the literature. [Display omitted] • Development of bio-based feedstock pellets for Material Extrusion. • Influence of binder composition and metallic powder size on the process. • Influence and control of the porosity along the whole process. • Low porosity and flawless net shape parts with optimised post-treatment stages. [ABSTRACT FROM AUTHOR]

Resonance Acoustic Mixing® (RAM) technology applies an external low-frequency vertical harmonic vibration to mix and deagglomerate fine and ultrafine granular materials. However, although this system is used for various applications, its mechanism is yet not well understood. To address this gap in the knowledge, in this study, a continuum model of powder in a low-frequency vertical harmonic vibration container was established, and spectral proper orthogonal decomposition was used to analyse the slip velocity. The mechanism of fine particle deagglomeration with vertical harmonic vibration is proposed. The slip velocity at the interface between the particles and air has a significant periodic character and produces a persistent drag force on the particles. As the vibrational excitation frequency increases, the bandwidth of the slip velocity becomes narrower and the peak frequency becomes equal to the vibrational frequency. The drag force produced by the periodic slip velocity is the main contribution to the deagglomeration force, which needs to overcome aggregation forces (e.g., van der Waals force). The strength of the deagglomeration force determines the overall deagglomeration performance and the particle size distribution of the agglomerates. [Display omitted] • The possible mechanism of deagglomeration of fine powder in RAM is proposed. • The proportion change model of different size agglomeration in RAM is established. • The spectral characteristics of slip velocity are studied by SPOD. [ABSTRACT FROM AUTHOR]

The particle size distribution (PSD) and particle morphology of metal powders undoubtedly affects the quality of parts produced by additive manufacturing (AM). It is, therefore, crucial to accurately know the PSD and morphology of these powders. There exist several measurement techniques for these quantities, but since each method is based on different physical phenomena, which are sensitive to different aspects of a particle's shape and size, it is unclear how the measured PSDs and morphology compare to one another. In this study, five different techniques are used: sieve analysis, dynamic imaging analysis, laser diffraction analysis, X-ray computed tomography (XCT), and scanning electron microscopy. The first three are commonly used in the powder metallurgy field while the last two are laboratory-based tools capable of providing robust size and shape data. Nominally identical samples of stainless-steel powders were produced via riffling, and each technique was employed to measure effectively the same PSD and in some cases the morphology. In this paper, the differences among these measurement techniques are explored by a comparison of the measured results. Besides the random variations of the various measurement processes, the difference in the results is partly due to the fact that the particles are not perfectly spherical and that there are many multi-particles present. Each of these affect the principle of each method differently. Three-dimensional particle morphology and size data collected via XCT is used to provide insight regarding the discrepancies among other sizing and morphology measurement techniques. (Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.) [Display omitted] • Common sizing techniques are compared to more robust laboratory-based methods • Each sizing method quantifies different physical properties • Appropriate metrics are carefully chosen when comparing different techniques • 3D XCT data provide insight into the discrepancies among other techniques • Complex morphologies present in gas atomized powders affect the measurement of size [ABSTRACT FROM AUTHOR]

Flowability parameters of powders measured by a shear cell is expected to depend on shear cell size, but details of that effect are lacking. In this work, we have systematically evaluated this using a number of powders under three preshear normal stresses using a ring shear tester. The flowability index (ff c) of a limestone powder (BCR 116) exhibited relatively small differences when measured on three shear cells of different sizes, S (~9.5 cm3) < M (~30 cm3) < L (~70 cm3). However, significant differences in measured ff c of common pharmaceutical powders were observed, where ff c of powders with a median particle size >22 μm was more than 15% higher using S than M. Large differences between data from M and L were found for powders with a median particle size >125 μm. Therefore, one must exercise caution when comparing flow properties of powders characterized using different shear cells. [Display omitted] • Powder flow parameters measured by shear cell testing depend on shear cell size. • Differences in measure flowability parameters tend to be larger for larger particles. • Certifying shear cell with a fine BCR 116 limestone powder does not eliminate the shear cell size effect. • Comparison of flowability parameters determined by different shear cells requires caution. [ABSTRACT FROM AUTHOR]

Room-temperature brittleness of pressureless sintered (PLS) titanium matrix composites is always a bottleneck for their engineering application. Herein, we report a novel powder metallurgy strategy to overcome this challenge by evading Kirkendall's pores. Specifically, the strategy mainly involves the coating of nanosized TiB 2 powder with stearic acid and subsequent reactive sintering with micron-sized TiH 2 powder. Interestingly, the TiB w /Ti composites prepared by PLS attain a nearly full density, whose porosity is as low as ~1.22%. Resultantly, the PLS composites exhibit large tensile plasticity as well as high strength, comparable or even superior to corresponding one of some ceramic phase-reinforced pure Ti matrix composites fabricated by pressure-assisted sintering or thermomechanical post-treatments. [Display omitted] • A novel powder metallurgy strategy was developed to prepared the TiB w /Ti composite. • Kirkendall's pore was significantly reduced by coating of nanosized TiB2 powder with stearic acid. • The pressureless-sintered composites exhibit improvement in tensile plasticity. • The results provides some guidelines for fabricating cost-effective titanium matrix composites. [ABSTRACT FROM AUTHOR]

Banana peels (Cavendish and Nay poovan) in ripe and raw form were dried using tray drying (T), microwave (M), microwave-convection (MC) and freeze drying (F) with ultrasonication (U) and combined treatment of carbonation and ultrasonication (CU) as pretreatments. SEM analysis showed microscopic channels in samples after U treatment, which were more ravine after CU. Based on bulk density, tapped density, porosity, angle of repose, colour parameters, viscosity, CU + F was found best drying combination followed by CU + MC. For selected samples, relative water sorption changes induced by U and CU were positive as the sorption surface area increased after given pre-treatments. Peleg model fitted best to experimental data for sorption studies. The water plasticizing effect of U and CU treatments on glass transition temperature (Tg) was predicted using Gordon-Taylor model. State diagram predicted critical moisture content (X c), 0.106 kg H 2 O/kg dry matter and critical water activity (a wc), 0.525 at 16 °C. [Display omitted] • Studied effect of hybrid drying techniques on physical properties of powders. • U and CU combined with selected drying techniques resulted in ameliorated results. • Sorption isotherms exhibited type III behaviour. • Plasticizing effect of water was adequately predicted by different models. • Constructed state diagram for prediction of X c and a wc [ABSTRACT FROM AUTHOR]

Metal powders used in directed energy deposition additive manufacturing are subjected to particle-particle and particle-gas interactions not captured through traditional powder characterization. Variations in powder performance were identified through mass flow rate measurements of lean (UNS S32101), standard (UNS S32205), and super (UNS S32750) duplex stainless steel powders specified for directed energy deposition on three commercial powder feeders. Across these different systems, the lean grade consistently displayed the lowest mass flow rates. Differences between the three powders were only identified with advanced powder and rheological characterization tools, which linked particle characteristics and rheological properties to powder flow and performance. A slight shift to a larger size distribution in the lean grade produced a higher percentage of larger particles with higher masses that resisted motion and increased flow resistance. Higher flow resistance was captured through higher cohesion strength and fluidization measurements during rheological testing. [Display omitted] • Powder particle size impacted the directed energy deposition (DED) process. • DED powder feeding is impacted by particle-particle and particle-gas interactions. • Larger particle sizes increased particle-particle and particle-gas flow resistance. • Increased flow resistance led to decreased mass flow rates during DED processing. [ABSTRACT FROM AUTHOR]

The influence of powder characteristics on the moldability of metal injection molding feedstock is relatively well understood, but remains difficult to quantify other than by real-scale injections. This study aims to correlate feedstock moldability performances with melt viscosity and dry powder rheology. Four stainless steel powders exhibiting different particle sizes and shapes were tested in dry conditions using an FT4 powder rheometer to obtain thirteen different powder rheology-related metrics. These powders were subsequently mixed with a wax-based binder to formulate four feedstocks that were tested in melt conditions using a rotational rheometer to characterize the injection-related rheology of the feedstock formulations. The moldability of the feedstocks was finally quantified using real-scale injections performed into a spiral mold cavity to measure the injected lengths, and the correlation between the dry and melt rheology metrics and the real-scale injection moldability was evaluated. Results showed that the feedstock melt viscosities and the injected lengths were almost perfectly correlated. Furthermore, two dry powder rheology metrics, namely, the normalized basic flow energy and the conditioned powder bulk density, showed the correlation with the feedstock moldability which is comparable to that obtained with the melt rheology. The results of this study indicate that although the feedstock melt viscosity and the dry powder rheology take fewer variables into account as compared to real-scale injections, these simplified tests (especially dry powder rheology) could be considered as rapid and reliable approaches to assessing the impact of powder characteristics on the moldability of powder-binder feedstocks used in metal injection molding. [Display omitted] • MIM powders were characterized for the first time by a powder rheometer in this paper. • The effect of size and shape of the powders on their rheology was clearly observable. • The powders were mixed with binders to create LPIM feedstocks. • The feedstocks were characterized by viscosity and moldabilty measurements. • Strong correlation was found between moldability, viscosity, and dry rheology. [ABSTRACT FROM AUTHOR]