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Metal powders are components with multidisciplinary usage as their application is very broad. Their consistent characterization across all disciplines is important for ensuring repeatable and trouble-free processes. Ten metal powders were tested in the study. In all cases, the particle size distribution and morphology (scanning electron microscope—...
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... particle size distributions of the first five metal powders are shown in Figure 3, another five in Figure 4 and the d 10 , d 50 and d 90 values are summarized in Table 1. Based on d 90 parameter, titanium powder contained the largest particles (452 µm), whereas, zinc powder contained the smallest particles (25 µm). For most metal powders, however, 90% of the particles ranged from about 60 to 90 µm. It can be concluded from the values that manganese powder has the widest span of particle distribution, which is also evident from the shape of the distribution curve (Figure 4) and from the SEM photograph shown as a part of Figure 5. The symmetrical distribution of the particle size is evident, e.g., by zinc powder (Figure 3). The SEM photographs suitably complement the characterization of metal powders ( Figure 5). The aforementioned manganese powder contains sharp-angled particles of various sizes. Smaller particles can fill the gap between the larger ones to ensure proper packing behavior. Stainless steel 316L and zinc powder contain separate spherical particles whose geometrical shape is close to the sphere. Aluminum powder contains, in addition to spherical particles, a minimum proportion of droplet-shaped particles whose exterior appearance is close to the ellipsoid. The photograph also proves that the smaller particles cover the surface of larger ones. Tin powder contains a considerable number of fine particles but also larger grains. The distribution span is wide. The particles are spherical or droplet-shaped and separated. Copper powder is composed of grains of irregular shape without geometric regularity. Bronze powder contains a mixture ranging from spherical particles to irregular shaped particles. Iron powder can be partly characterized by a sheet-like form of larger clumps. Titanium powder contains the largest particles, some with a dendritic shape. In the case of ferrite powder, there are agglomerates of fine, sharp-edged particles, either separate or packing coarser grains. The last two columns of Table 1 provide values for the preliminary assessment of the level of suitability of metal powder granulometry for the additive SLS and SLM production, according to Karapatis criteria (Equation (1)). The d 50 /d 10 > 10 criterion has not been fully met for any of the studied metal powders, although, for example, 316L stainless steel is used in additive production without problems. This ratio ranged from 1.5 to 5.3 when the highest value corresponds to the manganese powder. The value suggests that 50% of the particles are 5 times larger than 10% of finer particles. On the other hand, the d 90 /d 10 ≤ 19 criterion was met for all metal powders tested. As for metal powders examined by us, it applies that d 90 /d 10 ≤ 15. This requirement meets the condition of filling the free spaces between the coarse particles by fine grains to form the effective layer. Similar results regarding non-fulfilment/fulfilment of the criteria were also achieved in another study [12]. Therefore, another complementary criterion qualitatively specifying the suitability of metal powder granulometry for additive technology should be specified. To conclude from results, there is a certain balance between the stated ratios. Larger amounts of fine particles (up to about 6 µm) are agglomerated, while large amounts of larger particles often cause uneven (rough) surfaces. Both conditions are, therefore, marginal to create a suitable homogeneous powder layer for additive production. A further alternative of the addition is the determination of another characterization parameter, for instance the angle of internal ...
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... particle size distributions of the first five metal powders are shown in Figure 3, another five in Figure 4 and the d 10 , d 50 and d 90 values are summarized in Table 1. Based on d 90 parameter, titanium powder contained the largest particles (452 µm), whereas, zinc powder contained the smallest particles (25 µm). For most metal powders, however, 90% of the particles ranged from about 60 to 90 µm. It can be concluded from the values that manganese powder has the widest span of particle distribution, which is also evident from the shape of the distribution curve (Figure 4) and from the SEM photograph shown as a part of Figure 5. The symmetrical distribution of the particle size is evident, e.g., by zinc powder (Figure 3). The SEM photographs suitably complement the characterization of metal powders ( Figure 5). The aforementioned manganese powder contains sharp-angled particles of various sizes. Smaller particles can fill the gap between the larger ones to ensure proper packing behavior. Stainless steel 316L and zinc powder contain separate spherical particles whose geometrical shape is close to the sphere. Aluminum powder contains, in addition to spherical particles, a minimum proportion of droplet-shaped particles whose exterior appearance is close to the ellipsoid. The photograph also proves that the smaller particles cover the surface of larger ones. Tin powder contains a considerable number of fine particles but also larger grains. The distribution span is wide. The particles are spherical or droplet-shaped and separated. Copper powder is composed of grains of irregular shape without geometric regularity. Bronze powder contains a mixture ranging from spherical particles to irregular shaped particles. Iron powder can be partly characterized by a sheet-like form of larger clumps. Titanium powder contains the largest particles, some with a dendritic shape. In the case of ferrite powder, there are agglomerates of fine, sharp-edged particles, either separate or packing coarser grains. The last two columns of Table 1 provide values for the preliminary assessment of the level of suitability of metal powder granulometry for the additive SLS and SLM production, according to Karapatis criteria (Equation (1)). The d 50 /d 10 > 10 criterion has not been fully met for any of the studied metal powders, although, for example, 316L stainless steel is used in additive production without problems. This ratio ranged from 1.5 to 5.3 when the highest value corresponds to the manganese powder. The value suggests that 50% of the particles are 5 times larger than 10% of finer particles. On the other hand, the d 90 /d 10 ≤ 19 criterion was met for all metal powders tested. As for metal powders examined by us, it applies that d 90 /d 10 ≤ 15. This requirement meets the condition of filling the free spaces between the coarse particles by fine grains to form the effective layer. Similar results regarding non-fulfilment/fulfilment of the criteria were also achieved in another study [12]. Therefore, another complementary criterion qualitatively specifying the suitability of metal powder granulometry for additive technology should be specified. To conclude from results, there is a certain balance between the stated ratios. Larger amounts of fine particles (up to about 6 µm) are agglomerated, while large amounts of larger particles often cause uneven (rough) surfaces. Both conditions are, therefore, marginal to create a suitable homogeneous powder layer for additive production. A further alternative of the addition is the determination of another characterization parameter, for instance the angle of internal ...
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In the past decade, the sales of metal additive manufacturing systems have increased intensely. In particular, PBF-LB/M systems (powder bed fusion of metals using a laser-based system) represent a technology of great industrial interest, in which metallic powders are molten and solidified layer upon layer by a focused laser beam. This leads to a si...
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... The friction parameters (angle of internal friction and external friction) of the soils affect all processes where the soil is further manipulated. They are important indicators of possibilities for material use in a multitude of applications [13][14][15][16]. Friction parameters affect both the life of the tools in contact with the soil and the soil itself, in the form of possible intoxication by residues resulting from wear or degradative reactions in the soil. ...
Friction parameters such as the angle of internal friction and the external friction of soils (bulk materials) show the possibilities of further material use. These are, for example, possibilities for soil processing, handling, and storage. The determination of friction parameters is usually carried out under laboratory conditions. For the possibility of determining the properties of soils outside the laboratory in terms of immediate material response, a laboratory prototype was developed. The main objective for its development was to determine the effect of the shape of the friction surface when “sliding” on the soil. This was achieved with the help of validation equipment designed to measure, test, and validate the processes of raking, material piling, material transfer and removal, and tool movement or sliding on or in a material. It was found that by using an appropriate speed and normal load, the Jenike method can be applied to determine the angle of external friction over a shorter distance with an error of about 6–7.5% from the values measured on a calibrated shear machine. The results also showed that the method can be applied to detect the shear stresses that arise when a tool is plunged into a material, and thus predict the possible increase in energy loss during the process.
... The shear strength parameters of the IMS were also determined by the direct shear box test using a 0.05-mm/minute loading rate, where the cohesion was 69 kPa, and the angle of internal friction was 41.9° (or 55.3° when ignoring the cohesion) as shown in Table 3. The determined internal friction angle values are close to those reported in previous studies (Zegzulka et al. 2018). The direct shear box test charts are given in Fig. 5a for shear stress vs. normal stress, Fig. 5b for shear stress vs. horizontal displacement, Fig. 5c for vertical displacement vs. horizontal displacement, and Fig. 5d for the angle of internal friction vs. horizontal displacement. ...
The iron mill scale (IMS) is a by-product produced in the mills while rolling the hot iron. The IMS is a sustainable material that can be recycled and used again in a variety of applications, including concrete and asphalt mixes. The objective of this study was to analyze the IMS from a chemical, environmental, physical, and mechanical standpoint. Acceptable heavy metals limits were revealed by the environmental assessment. The material’s results for its chemical and physical properties were comparable to those of other materials that had previously been studied in previous works. Additionally, basic geotechnical and strength assessments were carried out on the IMS material, which revealed that it functions as a dense, dilative, non-plastic, and environmentally friendly sandy soil. The utilization of IMS into soil improvement was then numerically examined using three-dimensional finite element modeling, taking into account the aspects of soil-structure interaction. A typical medium-dense sandy soil, which supports various shallow foundations, was improved by mixing different IMS percentiles (ranging from 0 to 100%). Typical soil-slag’s parameters were considered for this analysis based on correlations collected from the literature. The improvement was quantified by the settlement improvement factor (SIF) determined from the numerical analysis (ranging from 1 to 3.5), and a dimensionless design chart was provided. Finally, a case study in Bahrain, where cavities are located based on site and geophysical observations, is presented utilizing the IMS in the cavity filling process. This study demonstrates the potential of IMS as a sustainable and affordable material for use in a variety of civil engineering applications.
... They found that for θ R < 30 very free flowing, 30-38 free flowing, 38-45 fair flowing, 45-55 Cohesive, and θ R > 55, very cohesive [15]. The angle of internal friction (δ): Zegzulka J et al. concluded in a study that the decrease in particle size and deviations from a spherical surface increase the angle of internal friction [16]. Further, literature has been reviewed to know the standard design parameters for chute design, such as chute inclination, minimum crosssectional area, width, existing opening, and hood height required. ...
... Both particle size and shape may impact θ if . [16] The determined value, i.e., 38.66 degrees, indicates higher value of θ if and higher value of internal friction, which creates more resistance for flow. ...
The Indian Cement Industry is on its path to achieve net-zero CO2 emission by 2070, for which alternative fuels have been identified as one of the levers. Refused Derived Fuel (RDF) has emerged as a potential alternative fuel; however, its use comes with technical challenges like transfer chute jamming. The study investigated the causes of chute jamming while handling RDF in an Indian cement plant and proclaimed the methods to overcome the same. The chute designing issues in handling RDF have not been addressed in the available literature, and this study provides parameters to design transfer chute satisfying the RDF handling challenges. Application of Discrete Element Modelling is suitable to simulate and analyze the current design issues and their improvement. It is observed that the physical & flow properties of RDF and its variation should be taken into consideration while designing the chute and the guidelines of available literature related to chute design parameters like chute cross-sectional area, width, inclination, exit opening, etc. are suitable for conventional bulk materials, but these need to be optimized for RDF.
... Therefore, the assessment of particle shapes presented in this paper is only illustrative based on scanning electron microscope (SEM) photographs. 39,40 . The measurements of AIF (δ, ϕ), ff c , and c had pre-shear normal stress of 10 000 Pa, shear points with normal stresses values of 250 Pa, 500 Pa, 1 000 Pa, 2 500 Pa, 5 000 Pa and 7 500 Pa. ...
The development of 3D printing methods and of printing materials enabled users to print 3D parts on demand, which is crucial in fast prototyping of new equipment or resolving problems with laboratory equipment both on Erath and in the universe. Due to relatively new solutions in the field of 3D printing, there are few studies on the possibility of using printed elements in measuring devices. In order to fill the gap in this area, the aim of this study was to investigate the possibility of using instruments made by material extrusion 3D printing method for measurement of selected mechanical-physical properties of bulk materials. We explore the feasibility of measuring bulk material mechanical-physical properties when there are obstacles for printing original or modified measuring instruments in common practice, such as the lower weight of the measuring instruments, the ability to pre-print a set of laboratory measuring instruments or to print the set on the spot, to replace a damaged part with a new 3D printed part on-demand, the logistical unavailability, customization of the standardized tests for better understanding of the behaviour of the particulate materials, and cheaper manufacturing cost. To achieve the goals a series of experiments such as Schulze’s ring shear tests, Freeman’s FT4 shear tests, compressibility tests, and Flow Rate and Stability tests were performed with use of original aluminium or steel made instruments and 3D printed instruments from polylactic acid and acrylic styrene acrylonitrile materials, using lunar regolith simulants LHS-1 and LMS-1 produced by CLASS Exolith Lab as a sample material. The results obtained from tests with original and printed instruments were then compared. The compared values of the effective angle of internal friction, linearized angle of internal friction, flow function, cohesion, compressibility, basic flowability energy, flow rate index, and stability index showed applicability of the 3D printed measuring instruments.
... Journal Pre-proof and then to determine for simulation of the movement along the vibratory conveyor the properties of these materials C1 to C8, Fig. 3 [42,43]. ...
Hard gelatine capsules remain a relevant dosage form for today's pharmaceutical manufacturing. A wide range of colour and print options supports marketing, brand image and patient loyalty. However, the filling of these capsules with various modern dosage forms and combinations thereof may affect their further processing. Therefore, a detailed study was carried out to assess the effect of mechanical-physical properties on the behaviour of differently filled hard gelatine capsules. Capsules filled with powder, free or fixed particles presenting drug microforms and also hard gelatine capsules themselves were evaluated. Basic mechanical-physical characterisation was performed on all samples. Furthermore, their transport on the vibrating conveyor was assessed and simulated using DEM. The results showed a significant influence mainly by the degree of capsule imbalance, i.e., the arrangement of particles in the capsule. It was found that the hard gelatine capsules showed an average of 15.6° lower values for the effective angle of internal friction compared to the powdered vitamin mixture, and in parallel, an average of 14.7° lower values for the static angle of repose were also recorded. The results of the experiments on the vibrating conveyor at a frequency setting of 15 Hz showed three times longer transport time for the vitamin mixture compared to the capsules. Increasing the frequency evened out these differences.
... The value of internal friction angle depends on soil properties and material preparation. In lack of such information in reactor scenarios, we chose = 35° as an average for metallic powders [Zegzulka et al., 2018]. ...
In recent years, a new 4th generation of nuclear reactors is under development. The most promising candidate to fulfil the requirement in terms of sustainability, safety, economic competitiveness, reduced nuclear waste production and proliferation resistance is the Sodium-cooled Fast Reactor concept. In this context, the ASTRID project is launched at CEA since 2009. The ASTRID project involves large R&D investment aiming to demonstrate on an industrial scale the relevance and performance of innovative technological breakthroughs. One of these breakthroughs is an innovative severe accident mitigation strategy developed for the ASTRID reactor CFV-V3 core design. The mitigation is achieved by implementing special design mitigation transfer tubes into the core and an in-vessel core catcher. The transfer tubes are envisaged to evacuate the mixture of reactive molten materials from the core region and thus decrease the probability and amplitude of further energetic power excursions.For the pre-conceptual phase of French Generation IV SFR program, it is necessary to have a robust demonstration of the performance of the mitigation devices in order to reduce uncertainties influencing the safety assessment. The theoretical demonstration is currently based on best-estimate calculations with code SIMMER. Previous reactor calculations for the ASTRID design on severe accident scenarios with mitigation strategy have demonstrated that the discharge of degraded core inventory via transfer tubes may be efficient. On the other hand, SIMMER simulations highlighted uncertainties linked to the degraded core motion, in particular solid debris components inside the transfer tubes. The consideration of solid particles is of high importance in CFV concept where the low energetic natural behavior of the core prevents massive fuel melting and enhances the production of fuel debris from pellet fragmentation.In this context, the thesis focuses on the relocation mechanism of the degraded core inventory via transfer tubes in the frame of the SIMMER code. The objective is to improve SIMMER modelling of particle-size solid debris dynamics, in order to predict the scenario of molten/degraded core discharge with a higher confidence and to contribute therefore to the safety evaluation of future generation SFRs.The thesis work constitutes the development and validation of a comprehensive modelling set for the dynamics of dense particulate flows in the SIMMER-V code. Firstly, the general context in which the thesis work has been defined is exposed. Secondly, we focus on the localized physical phenomena taking place during the discharge process via the transfer tube and its current state-of-the-art numerical modelling by SIMMER code. In contrast to the state-of-the-art approach, the main outcomes of the bibliographic review around solid particle dynamics are presented. Concluding on this, the developed models (inspired by granular flow theory correlations) and their numerical implementation into the SIMMER code environment are introduced. The impact of such models is demonstrated through comparison with the original SIMMER particle approach through simplified test cases for which analytical or empirical solutions exist. After, the performances of the new models are studied for an integral effect test together with a sensitivity study highlighting the influence of uncertain modelling parameters. Then we return to the initial motivation of the thesis work about the simulation of the whole reactor in case of a reference accidental scenario. Following the entire transient evolution, the mitigation performance applying the newly developed particle dynamics models is assessed. Lastly, the conclusions are summarized, and perspectives for future research on the continuation of this work are outlined in the seventh chapter.
... Only few studies have discussed that the friction angle can widely vary depending on 1) particle size, 2) distribution of size in filler mixture, and 3) distribution of shape in filler mixture [19,20]. Therefore, based on the fact metallic powder has an internal friction angle ranging from 27.8° to 40° [21] and the alumina beads being considered in the TEDS have different sizes (friction-lowering effect) and relatively large diameters (either friction-lowering or elevating effect), we set a conservative estimate for the friction angle at 60°. ...
The growing uncertainties of non-dispatchable renewable generation have increased the need for flexible and reliable thermal load management. Integrated nuclear-renewable energy system (IES) is a clean energy technology that combines renewable energy resources with carbon-free baseload generators such as nuclear power plants, to enable low-cost supplies of carbon-free heat and electricity on demand. A key task to future IES deployment is to ensure the flexible and reliable delivery of nuclear thermal energy to its subsystems. Idaho National Laboratory has recently built a Thermal Energy Delivery System (TEDS) to demonstrate the integration of intermittent energy resources (i.e., renewables) with the main carbon-free baseload plant within an IES configuration, where a granular packed-bed thermal energy storage (TES) tank is installed. The packed-bed TES is a key component of TEDS that enables dynamic charge and discharge of the heat as required to meet the varying energy demand. This paper discusses the potential thermo-mechanical concern of the packed-bed TES tank of the TEDS, (i.e., thermal ratcheting). To reasonably reduce a problem size, a one-way coupled computational model was established on the Abaqus platform to evaluate the design parameters influencing thermo-mechanical deformation of the TES tank, within the operation scope of the TEDS. The evolution of hoop stress was investigated with the coupled Eulerian-Lagrangian method and the Drucker-Prager model. Significant effort was devoted to determining the effects of the bed and tank-material properties, temperature profiles, and tank-wall/beds friction on the stress analysis. This study shows the maximum hoop stress predicted under the TEDS operating conditions falls within 11% of the TES tank-material limit (i.e., yield strength). However, efforts are still needed to improve the model by utilizing temperature-dependent tank-material and realistic bed properties measured in the TEDS.
... The particles with such morphology do not resist flow due to very little friction between them at the microscopic level. This reduction in friction is due to the absence of surface asperities (Zegzulka et al., 2018). The low flowability of the 1S-6H and 2S-12H powders is due to the angular, sharp-edged morphology of the particles (Fig. 9) as oppose to the more rounded particles in 3S-16H. ...
This paper addresses the imperative need to develop sustainable recycle technologies for high value machining swarf generated during the processing of Ti6Al4V alloy. A novel recycling process based on multi-stage ball milling is proposed. The process converts Ti6Al4V swarf into a powder feedstock suitable for additive manufacturing (AM). The powders produced from the cleaned swarf using an in-house designed and fabricated tumbler ball mill were characterised in terms of their morphology, particle size, flowability and spreadability. It was found that the dominant effect of milling with Ø 25 mm balls was particle size reduction (up to ∼ 40%) and the primary effect with smaller balls of Ø 6.25 mm was modification of particle morphology from irregular to rounded shape; thus, necessitating adoption of a multi-stage milling approach to achieve required size and morphology. Ti6Al4V powder having particle size in the range of 40–200 μm and near-spherical morphology was obtained after multi-stage ball milling up to 18 h. The powder characteristics were comparable or superior to the powder produced by generally used gas atomisation (GA) process. The suitability of the powders for AM was established through direct metal laser sintering (DMLS). The proper melting of the optimally prepared powder occurs at 1000 mm/s scanning speed and 310 W of laser power. The developed multi-stage ball milling process was assessed vis-à-vis gas atomisation using life cycle assessment (LCA). LCA revealed that the proposed ball milling method consumed lower energy (∼59%), had lower eco-cost (∼82%), and lesser global warming potential (GWP) (∼68%).
... It creates a shear area in which the particles move and resist each other (shear stress). This shear stress, depending on the adjusted normal load, is then converted using software (Schulze-RST CONTROL 95) (11) to the internal friction efficient (AIFE), linearised (AIFLIN) and steady-state flow (AIFSF) 33 . Each sample was measured 10 times at a normal load of 20,000 Pa, 10 times at 10,000 Pa and 10 times at 5000 Pa. ...
This work presents a comprehensive overview of the mechanical-physical parameters of the transport material affecting the vibratory transport. For this purpose, spruce pellets of different lengths, oak rods and spruce crush were tested. The determined parameters were particle size distribution and shape, internal friction, static and dynamic angle of repose. The samples were transported by a patented validation vibrating conveyor. Various settings were used. The results show that by changing the shape, it is possible to reduce friction or resistance as well as energy intensity during transport. It was observed that perfect shapes and lighter particles have lower friction, but a more pronounced bounce. Therefore, it does not form a typical pattern during transport, as in the case of an imperfectly shaped one. There is also included a simulation of the discrete element method. The study shows the possibility of the vibration machine where the material can be conveyed either directionally or sorted.
... Carney Funnel measurements of irregular Ti6Al4V powder showed a decrease in the value of angle of repose by ~15 • after BM of 18 h (Gökelma et al., 2018). This decrease is primarily due to the reduction of inter-particle friction during the flow of near-spherical particles (Zegzulka et al., 2018). Usually, in AM systems, the spherical powder is desired due to its enhanced bulk properties which assure the perfect flow or layer spread in comparison to non-spherical CP (Mehrabi et al., 2021). ...
The dependence on conventional metal cutting technologies to satisfy consumer demands for more customised products and services is contributing to the generation of ever-increasing metallic waste in the form of machining chips (MCs). Metallic MCs are of high value if recycled by sustainable techniques. Conventional recycling by melting the MCs for industrious use is neither economical nor environment friendly. Thus, the advanced technologies for clean recycling of MCs for industrious use are the need of the hour. In this paper, consideration is given to the role of one such advanced recycling technology: ball milling (BM). The efficacy of BM for recycling MCs by converting them into chip powder (CP) is evaluated. The produced chip powder (CP) can be utilized as feedstock powder in various powder bed fusion (PBF) additive manufacturing processes like laser engineered net shaping (LENS) and electron beam melting (EBM) for the manufacturing of near-net shaped products. The consequences of adopting this novel recycling technology on industrial sustainability are not well understood and this exploratory study draws on publicly available data to provide insights into the impacts of BM on sustainability. Benefits of BM are found to exist which include promising results in obtaining 70–90% sphericity with the utilization of 20–30% less energy in comparison to conventional powder production techniques. As an immature technology, there are substantial challenges to these benefits being realised. This paper summarises these advantages, challenges, and discusses the implications of BM as sustainable recycling technology in terms of process parameters on the mechanical, physical, and morphological properties of the CP produced. In addition, a framework is presented which suggests the plausible methodology for recycling MCs into CP from the generation stage to the final utilization stage.
