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Item Embargo Stakeholder perspectives on the costs and benefits of circular construction(Nature, 2024) Ferhat Karaca, Aidana Tleuken, Hamad Hassan Awan, Rand Askar, Mustafa Selçuk Çıdık, Anel Iskakova, Ali Turkyilmaz, Thomas Laudal, Serdar Durdyev, Huseyin Atakan Varol, Adriana Salles, Diāna Bajāre, Tatjana Tambovceva, Gabriel Zsembinszki, Genesis Camila Cervantes Puma, Zhanna Kapsalyamova, Dorina Kripa, Dina Azhgaliyeva, Xhesila Nano, Luisa F. Cabeza & Luís BragançaThe construction industry significantly impacts the environment through natural resource depletion and energy consumption, leading to environmental degradation. Circular Economy (CE) material efficiency strategies—such as material reuse, design for disassembly, prefabrication, and recycling—offer promising solutions for reducing resource consumption and waste. This paper explores stakeholders’ perspectives on the costs and benefits of implementing CE material efficiency strategies in the construction industry, using the 3-R (Reduce, Reuse, Recycle) framework. By analyzing data from 382 participants, it assesses perceptions of costs and benefits, uncovering regional differences. The findings highlight that studied European stakeholders prioritize reuse and design for disassembly, while studied non-European countries focus on offsite production and material reuse optimization. Despite these differences, both groups view waste reduction as a key benefit, due to the cost savings it provides. By highlighting regional drivers and barriers to CE adoption, this research establishes a foundation for developing targeted policies and collaborative strategies to advance CE implementation in construction worldwide.Item Embargo A GIS-Based emergency response and management support framework for Earthquake crisis: A case study of Antakya and Kahramanmaras earthquake in Turkey(Elsevier, 2024) Hamad Hassan Awan, Marzhan Kabdrakhmanova, Huseyin Atakan Varol, Ferhat KaracaEarthquakes can cause significant damage, including loss of lives, collapsed buildings, and blocked roads. However, the severity and frequency of earthquakes cannot be accurately predicted. To mitigate these effects, successful disaster management, particularly in improving post-earthquake road network connectivity, is crucial. Therefore, this study presents a novel satellite imagery-based approach for identifying post-earthquake road blockage and to assess its impact on urban infrastructure and emergency response management. This study utilised real-world pre- and post-earthquake satellite images of the earthquake that struck Turkey on February 6, 2023 using ArcGIS Pro. The results demonstrated that in the scenario when people in affected areas (incidents) tried to escape to emergency gathering zones, out of the initial 126 incident locations in Antakya, 101 of them experienced alterations in the selected routes after the earthquake. In Kahramanmaras, out of 35 incidents, 28 experienced changes in the selected routes. In the case of emergency vehicles (firefighting, medical aid, etc.) traveling to affected areas, some emergency vehicles were assigned a great number of incidents, whereas some vehicles had no incidents assigned to them. The findings of this study suggest that the developed framework can identify road blockage and inefficiencies in an emergency response framework with high accuracy. Therefore, the approach presented in this paper can be implemented to develop a practical geographic information system (GIS) based model to enhance the emergency response management for potential future earthquakes. Thereby, this study can facilitate the level of resilience of urban environments to withstand and adapt to future crises.Item Open Access INVESTIGATING THE SYNTHESIS OF NMC AND LCO THIN-FILM CATHODES FOR ENHANCED PERFORMANCE IN LITHIUM-ION BATTERIES(School of Engineering and Digital Sciences, 2023-04) Kabashev, ZhaksylykThin-film lithium batteries are designed to improve the longevity, storage capacity, energy density, and safety level of lithium batteries. The materials of the thin-film of electrodes should fit several criteria, such as ionic conductivity, electrochemical stability, and optimized solid electrolyte characteristics. This study investigated the electrochemical performance of an NMC-based lithiumion battery, with a focus on understanding the voltage-capacity relationship and cycling performance. The obtained experimental results showed a peak voltage of 3.1 V, which is considerably lower than the expected value of 4.2 V for NMC-based cells. Additionally, the specific capacity was found to be 2.09 μAh/g, which is significantly lower than the reported capacities in the literature for similar battery chemistries. The deviation from the expected performance suggests potential issues in the materials, cell design, or experimental conditions. Despite the suboptimal performance, this study provides valuable insights into the challenges associated with NMC-based lithium-ion batteries and serves as a foundation for further investigations and optimizations. Future work should focus on identifying the factors contributing to the observed performance and exploring strategies to enhance the electrochemical behavior of NMC-based cells to make them suitable for various applications, such as electric vehicles and energy storage systems.Item Open Access INFLUENCE OF MIXING ORDER ON THE SYNTHESIS OF GEOPOLYMER CONCRETE(Polymers, 2022) Mukhametkaliyev, Timur; Ali, Md. Hazrat; Kutugin, Viktor; Savinova, Olesya; Vereschagin, VladimirGeopolymers are high-performance, cost-effective materials made from industrial waste that ideally fit the needs of 3D printing technology used in construction. The novelty of the present work lies in the investigation of methods to mix geopolymer concrete from fly ash (FA) class F, ground granulated blast furnace slag (GGBS), and raw calcined kaolin clay (RCKC) to determine the mixing procedure which provides the best mechanical strength and structural integrity. The experimental results show that aluminosilicates with different reaction parameters when mixed one after another provide the optimal results while the geopolymer concrete possesses the highest compressive strength and the denser structure. The results demonstrated that the reactivity of GGBS, FA, and RCKC increased for different depolymerization speeds of the selected aluminosilicates. This research will provide results on how to improve the mixing order for geopolymer synthesis for 3D printing demands. The highest compressive strength and denser structure of geopolymer concrete is achieved when each type of aluminosilicate is mixed with an alkaline medium separately.Item Open Access PHASE BEHAVIOR OF ION-CONTAINING POLYMERS IN POLAR SOLVENTS: PREDICTIONS FROM A LIQUID-STATE THEORY WITH LOCAL SHORT-RANGE INTERACTIONS(Polymers, 2022) Wang, Yanwei; Qiu, Qiyuan; Yedilbayeva, Arailym; Kairula, Diana; Dai, LiangThe thermodynamic phase behavior of charged polymers is a crucial property underlying their role in biology and various industrial applications. A complete understanding of the phase behaviors of such polymer solutions remains challenging due to the multi-component nature of the system and the delicate interplay among various factors, including the translational entropy of each component, excluded volume interactions, chain connectivity, electrostatic interactions, and other specific interactions. In this work, the phase behavior of partially charged ion-containing polymers in polar solvents is studied by further developing a liquid-state (LS) theory with local shortrange interactions. This work is based on the LS theory developed for fully-charged polyelectrolyte solutions. Specific interactions between charged groups of the polymer and counterions, between neutral segments of the polymer, and between charged segments of the polymer are incorporated into the LS theory by an extra Helmholtz free energy from the perturbed-chain statistical associating fluid theory (PC-SAFT). The influence of the sequence structure of the partially charged polymer is modeled by the number of connections between bonded segments. The effects of chain length, charge fraction, counterion valency, and specific short-range interactions are explored. A computational App for salt-free polymer solutions is developed and presented, which allows easy computation of the binodal curve and critical point by specifying values for the relevant model parameters.Item Unknown RECYCLING NANOARCHITECTONICS OF GRAPHENE OXIDE FROM CARBON FIBER REINFORCED POLYMER BY THE ELECTROCHEMICAL METHOD(Nanomaterials, 2022) Ling, Li; Wu, Chao; Xing, Feng; Memon, Shazim Ali; Sun, HongfangIn this paper, an electrochemical method was proposed to recycle nanoarchitectonics of graphene oxide (GO) from carbon fiber reinforced polymer (CFRP). In the recycling process, NaCl solution with varied concentrations (3% and 10%) and tap water were used as electrolyte, while the impressed current density varied from 2.67 A/m2 to 20.63 A/m2. The results indicated that in NaCl electrolyte, the obtained nanoarchitectonics of GO contained a large amount of nano-carbon onions (NCO) produced by etching CFRP, while high purity GO was produced when tap water was used as electrolyte. The higher current density improved the production efficiency and resulted in a finer GO particle size. The proposed recycling method of GO is economical and simple to operate. It also provides an alternate approach to handle discarded CFRP.Item Unknown APPLICATION OF RESPONSE SURFACE METHODOLOGY FOR OPTIMIZATION OF NANOSIZED ZINC OXIDE SYNTHESIS CONDITIONS BY ELECTROSPINNING TECHNIQUE(Nanomaterials, 2022) Rakhmanova, Aizhan; Kalybekkyzy, Sandugash; Soltabayev, Baktiyar; Bissenbay, Aiman; Kassenova, Nazym; Bakenov, Zhumabay; Mentbayeva, AlmagulZinc oxide (ZnO) is a well-known semiconductor material due to its excellent electrical, mechanical, and unique optical properties. ZnO nanoparticles are widely used for the industrial-scale manufacture of microelectronic and optoelectronic devices, including metal oxide semiconductor (MOS) gas sensors, light-emitting diodes, transistors, capacitors, and solar cells. This study proposes optimization of synthesis parameters of nanosized ZnO by the electrospinning technique. A Box– Behnken design (BB) has been applied using response surface methodology (RSM) to optimize the selected electrospinning and sintering conditions. The effects of the applied voltage, tip-to-collector distance, and annealing temperature on the size of ZnO particles were successfully investigated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm the formation of polyvinylpyrrolidone-zinc acetate (PVP-ZnAc) fibers and nanostructured ZnO after annealing. X-ray diffraction (XRD) patterns indicate a pure phase of the hexagonal structure of ZnO with high crystallinity. Minimal-sized ZnO nanoparticles were synthesized at a constant applied potential of 16 kV, with a distance between collector and nozzle of 12 cm, flow rate of 1 mL/h, and calcination temperature of 600 C. The results suggest that nanosized ZnO with precise control of size and morphology can be fabricated by varying electrospinning conditions, precursor solution concentration, and sintering temperature.Item Unknown NANO GEOCHEMISTRY(Nanomaterials, 2022) Schäfer, Thorsten; Lee, Woojin; Darbha, Gopala KrishnaIt is our great pleasure to briefly introduce our motivation to collect scientific contributions for this Special Issue, entitled “Nano Geochemistry”. The geophysical and chemical dynamics at the solid–water interface, ultimately, control the transport properties of natural and engineered colloids/nanoparticles via, e.g., mineral dissolution/precipitation reactions and the variation in nano- to microscale surface roughness [1,2]. The nanoparticles present can significantly influence the mobility of strongly sorbing organic and/or inorganic contaminants in groundwater systems, frequently used as a drinking-water resource [3]. In addition, wetting/drying cycles in the vadose zone have attracted interest, concerning the mobility of organic nanoparticles/colloids [4], and the nanoparticle composition and element redox state can significantly change, especially in karst systems, due to seasonal variations [5]. More pronounced changes, due to extreme weather events, potentially triggered by climate change, have been observed [6]. The generation of these nanoparticles based on the nucleation and growth theory (classical or non-classical crystallization pathway) for the formation of nanoparticles in natural systems is still a matter of debate. It could be shown, e.g., for magnetite, that the nanoparticle formation in natural systems proceeds through rapid agglomeration of nanometric primary particles. In contrast to the nucleation of other minerals, no intermediate bulk phase is involved [7]. Nucleation and nanoparticle formation, associated with surfaces, are also key aspects of the formation of, e.g., Au ore deposits and hydrothermal vents [2,8], also referred to as the field of nanogeologyItem Unknown SELF-POWERED ORGANOMETAL HALIDE PEROVSKITE PHOTODETECTOR WITH EMBEDDED SILVER NANOWIRES(Nanomaterials, 2022) Beisenbayev, Almaz R.; Sadirkhanov, Zhandos T.; Yerlanuly, Yerassyl; Kaikanov, Marat I.; Jumabekov, Askhat N.Metal–semiconductor–metal (MSM) configuration of perovskite photodetectors (PPDs) suggests easy and low-cost manufacturing. However, the basic structures of MSM PPDs include vertical and lateral configurations, which require the use of expensive materials such as transparent conductive oxides or/and sophisticated fabrication techniques such as lithography. Integrating metallic nanowire-based electrodes into the perovskite photo-absorber layer to form one-half of the MSM PPD structure could potentially resolve the key issues of both configurations. Here, a manufacturing of solution-processed and self-powered MSM PPDs with embedded silver nanowire electrodes is demonstrated. The embedding of silver nanowire electrode into the perovskite layer is achieved by treating the silver nanowire/perovskite double layer with a methylamine gas vapor. The evaporated gold layer is used as the second electrode to form MSM PPDs. The prepared MSM PPDs show a photoresponsivity of 4 105 AW1 in the UV region and 2 105 AW1 in the visible region. On average, the devices exhibit a photocurrent of 1.1 106 A under white light (75 mW cm2) illumination with an ON/OFF ratio of 83.4. The results presented in this work open up a new method for development and fabrication of simple, solution-processable MSM self-powered PPDs.Item Unknown THE QUANTITATIVE CASE-BY-CASE ANALYSES OF THE SOCIO-EMOTIONAL OUTCOMES OF CHILDREN WITH ASD IN ROBOT-ASSISTED AUTISM THERAPY(Multimodal Technologies and Interaction, 2022) Telisheva, Zhansaule; Amirova, Aida; Rakhymbayeva, Nazerke; Zhanatkyzy, Aida; Sandygulova, AnaraWith its focus on robot-assisted autism therapy, this paper presents case-by-case analyses of socio-emotional outcomes of 34 children aged 3–12 years old, with different cases of Autism Spectrum Disorder (ASD) and Attention Deficit Hyperactivity Disorder (ADHD).We grouped children by the following characteristics: ASD alone (n = 22), ASD+ADHD (n = 12), verbal (n = 11), non-verbal (n = 23), low-functioning autism (n = 24), and high-functioning autism (n = 10). This paper provides a series of separate quantitative analyses across the first and last sessions, adaptive and non-adaptive sessions, and parent and no-parent sessions, to present child experiences with the NAO robot, during play-based activities. The results suggest that robots are able to interact with children in social ways and influence their social behaviors over time. Each child with ASD is a unique case and needs an individualized approach to practice and learn social skills with the robot. We, finally, present specific child–robot intricacies that affect how children engage and learn over time as well as across different sessions.Item Unknown ELECTROCHEMICAL CHARACTERISTICS OF SHEWANELLA LOIHICA PV-4 ON RETICULATED VITREOUS CARBON (RVC) WITH DIFFERENT POTENTIALS APPLIED(Molecules, 2022) Wang, Shixin; Zhang, Xiaoming; Marsili, EnricoThe current output of an anodic bioelectrochemical system (BES) depends upon the extracellular electron transfer (EET) rate from electricigens to the electrodes. Thus, investigation of EET mechanisms between electricigens and solid electrodes is essential. Here, reticulated vitreous carbon (RVC) electrodes are used to increase the surface available for biofilm formation of the known electricigen Shewanella loihica PV-4, which is limited in conventional flat electrodes. S. loihica PV- 4 utilizes flavin-mediated EET at potential lower than the outer membrane cytochromes (OMC), while at higher potential, both direct electron transfer (DET) and mediated electron transfer (MET) contribute to the current output. Results show that high electrode potential favors cell attachment on RVC, which enhances the current output. DET is the prevailing mechanism in early biofilm, while the contribution of MET to current output increased as the biofilm matured. Electrochemical analysis under starvation shows that the mediators could be confined in the biofilm. The morphology of biofilm shows bacteria distributed on the top layer of honeycomb structures, preferentially on the flat areas. This study provides insights into the EET pathways of S. loihica PV-4 on porous RVC electrodes at different biofilm ages and different set potential, which is important for the design of real-world BES.Item Unknown KINETIC ANALYSIS OF METHANE HYDRATE FORMATION WITH BUTTERFLY TURBINE IMPELLERS(Molecules, 2022) Longinos, Sotirios Nik.; Longinou, Dionisia Dimitra; Myrzakhmetova, Nurbala; Akimbayeva, Nazgul; Zhursumbaeva, Mariamkul; Abdiyev, Kaldibek; Toktarbay, Zhexenbek; Parlaktuna, MahmutHeat generation during gas hydrate formation is an important problem because it reduces the amount of water and gas that become gas hydrates. In this research work, we present a new design of an impeller to be used for hydrate formation and to overcome this concern by following the hydrodynamic literature. CH4 hydrate formation experiments were performed in a 5.7 L continuously stirred tank reactor using a butterfly turbine (BT) impeller with no baffle (NB), full baffle (FB), half baffle (HB), and surface baffle (SB) under mixed flow conditions. Four experiments were conducted separately using single and dual impellers. In addition to the estimated induction time, the rate of hydrate formation, hydrate productivity and hydrate formation rate, constant for a maximum of 3 h, were calculated. The induction time was less for both single and dual-impeller experiments that used full baffle for less than 3 min and more than 1 h for all other experiments. In an experiment with a single impeller, a surface baffle yielded higher hydrate growth with a value of 42 108 mol/s, while in an experiment with dual impellers, a half baffle generated higher hydrate growth with a value of 28.8 108 mol/s. Both single and dual impellers achieved the highest values for the hydrate formation rates that were constant in the full-baffle experiments.Item Open Access MOLECULAR MODELING IN ANION EXCHANGE MEMBRANE RESEARCH: A BRIEF REVIEW OF RECENT APPLICATIONS(Molecules, 2022) Karibayev, Mirat; Kalybekkyzy, Sandugash; Wang, Yanwei; Mentbayeva, AlmagulAnion Exchange Membrane (AEM) fuel cells have attracted growing interest, due to their encouraging advantages, including high power density and relatively low cost. AEM is a polymer matrix, which conducts hydroxide (OH) ions, prevents physical contact of electrodes, and has positively charged head groups (mainly quaternary ammonium (QA) groups), covalently bound to the polymer backbone. The chemical instability of the quaternary ammonium (QA)-based head groups, at alkaline pH and elevated temperature, is a significant threshold in AEMFC technology. This review work aims to introduce recent studies on the chemical stability of various QA-based head groups and transportation of OH ions in AEMFC, via modeling and simulation techniques, at different scales. It starts by introducing the fundamental theories behind AEM-based fuel-cell technology. In the main body of this review, we present selected computational studies that deal with the effects of various parameters on AEMs, via a variety of multi-length and multi-time-scale modeling and simulation methods. Such methods include electronic structure calculations via the quantum Density Functional Theory (DFT), ab initio, classical all-atom Molecular Dynamics (MD) simulations, and coarse-grained MD simulations. The explored processing and structural parameters include temperature, hydration levels, several QA-based head groups, various types of QA-based head groups and backbones, etc. Nowadays, many methods and software packages for molecular and materials modeling are available. Applications of such methods may help to understand the transportation mechanisms of OH ions, the chemical stability of functional head groups, and many other relevant properties, leading to a performance-based molecular and structure design as well as, ultimately, improved AEM-based fuel cell performances. This contribution aims to introduce those molecular modeling methods and their recent applications to the AEM-based fuel cells research community.Item Open Access CHANGES IN PHYTOPLANKTON COMMUNITY COMPOSITION AND PHYTOPLANKTON CELL SIZE IN RESPONSE TO NITROGEN AVAILABILITY DEPEND ON TEMPERATURE(Microorganisms, 2022) Dashkova, Veronika; Malashenkov, Dmitry V.; Baishulakova, Assel; Davidson, Thomas A.; Vorobjev, Ivan A.; Jeppesen, Erik; Barteneva, Natasha S.The climate-driven changes in temperature, in combination with high inputs of nutrients through anthropogenic activities, significantly affect phytoplankton communities in shallow lakes. This study aimed to assess the effect of nutrients on the community composition, size distribution, and diversity of phytoplankton at three contrasting temperature regimes in phosphorus (P)–enriched mesocosms and with different nitrogen (N) availability imitating eutrophic environments. We applied imaging flow cytometry (IFC) to evaluate complex phytoplankton communities changes, particularly size of planktonic cells, biomass, and phytoplankton composition. We found that N enrichment led to the shift in the dominance from the bloom-forming cyanobacteria to the mixed-type blooming by cyanobacteria and green algae. Moreover, the N enrichment stimulated phytoplankton size increase in the high-temperature regime and led to phytoplankton size decrease in lower temperatures. A combination of high temperature and N enrichment resulted in the lowest phytoplankton diversity. Together these findings demonstrate that the net effect of N and P pollution on phytoplankton communities depends on the temperature conditions. These implications are important for forecasting future climate change impacts on the world’s shallow lake ecosystems.Item Open Access IODIDE REMOVAL BY RESORCINOL-FORMALDEHYDE CARBON AEROGELS(Materials, 2022) Domán, Andrea; Battalgazy, Bekassyl; Dobos, Gábor; Kiss, Gábor; Tauanov, Zhandos; László, Krisztina; Zorpas, Antonis A.; Inglezakis, Vassilis J.The adsorption technique is widely used in water purification, and its efficiency can be significantly improved by target-specific adsorbent design. Research on iodine and its ion removal from water has attracted a great deal of interest due to increased concentrations in the environment and acute toxic effects, e.g., in human thyroid cells. In this work, the iodide removal performance of two high-surface-area resorcinol–formaldehyde-based carbon aerogels was studied under acidic conditions. The BET surface area was 790 m2/g (RF_ac) and 375 m2/g (RMF-GO), with a corresponding micropore ratio of 36 and 26%, respectively. Both aerogels showed outstanding adsorption capacity, exceeding the reported performance of other carbons and Ag-doped materials. Owing to its basic nature, the RMF-GO carbon aerogel showed higher I capacity, up to 97 mg/g, than the acidic RF_ac, which reached a capacity of 82 mg/g. The surface chemistry of the aerogels also played a distinct role in the removal. In terms of kinetics, RF_ac removed 60% of the iodide ions and RMF-GO 30% within 8 h. The removal kinetics was of the first order, with a half-life of 1.94 and 1.70 h, respectively.Item Open Access A NOVEL METHOD FOR THE DETERMINATION OF THE LATERAL DIMENSIONS OF 2D RECTANGULAR FLAKES(Materials, 2022) Papathanasiou, Thanasis D.; Tsiantis, Andreas; Wang, YanweiWe present a novel method for the determination of the lateral dimensions of thin rectangular flakes, as they exist randomly dispersed in flake composites. Knowledge of flake size and shape is essential for the correct prediction of the mechanical, electrical, thermal and barrier properties of flake composites. The required information is the distribution function of lengths of the lines representing the intersection of flakes with a sectioning plane, as seen in cross-sections of composite samples used in optical or electron microscopy or obtained using tomographic imaging techniques. The key observation is that the major peak of the distribution function coincides with the short dimension S of the flake while a secondary peak corresponds to its long dimension W. These observations are explained using Monte-Carlo simulations, as well as deterministic, geometry-based modeling and probability analysis. Since the strength of the secondary peak diminishes with increasing flake aspect ratio r = W/S, we develop two additional methods for the determination of W. The first finds W from the maximum intersection length; this procedure is justified by computing the relevant probability fields through Monte-Carlo simulations. The second method finds r from the average intersection length and is valid in the range 1 < r < 15. The performance of these techniques is tested and found to be very good using blind experiments in numerically sectioned specimens.Item Open Access THE POST-PROCESSING OF ADDITIVE MANUFACTURED POLYMERIC AND METALLIC PARTS(Journal of Manufacturing and Materials Processing, 2022) Syrlybayev, Daniyar; Seisekulova, Aidana; Talamona, Didier; Perveen, AsmaThe traditional manufacturing industry has been revolutionized with the introduction of additive manufacturing which is based on layer-by-layer manufacturing. Due to these tool-free techniques, complex shape manufacturing becomes much more convenient in comparison to traditional machining. However, additive manufacturing comes with its inherent process characteristics of high surface roughness, which in turn effect fatigue strength as well as residual stresses. Therefore, in this paper, common post-processing techniques for additive manufactured (AM) parts were examined. The main objective was to analyze the finishing processes in terms of their ability to finish complicated surfaces and their performance were expressed as average surface roughness (Sa and Ra). The techniques were divided according to the materials they applied to and the material removal mechanism. It was found that chemical finishing significantly reduces surface roughness and can be used to finish parts with complicated geometry. Laser finishing, on the other hand, cannot be used to finish intricate internal surfaces. Among the mechanical abrasion methods, abrasive flow finishing shows optimum results in terms of its ability to finish complicated freeform cavities with improved accuracy for both polymer and metal parts. However, it was found that, in general, most mechanical abrasion processes lack the ability to finish complex parts. Moreover, although most of post-processing methods are conducted using single finishing processes, AM parts can be finished with hybrid successive processes to reap the benefits of different post-processing techniques and overcome the limitation of individual process.Item Open Access STUDY OF SLA PRINTING PARAMETERS AFFECTING THE DIMENSIONAL ACCURACY OF THE PATTERN AND CASTING IN RAPID INVESTMENT CASTING(Journal of Manufacturing and Materials Processing, 2022) Badanova, Nazym; Perveen, Asma; Talamona, DidierDimensional accuracy and geometric characteristics of the manufactured parts bear significant importance in product assembly. In Rapid Investment Casting, these characteristics can be affected by the printing parameters of the Additive Manufacturing method used in the pattern production process. Stereolithography is one of the important AM techniques mostly exploited in RIC due to its accuracy, smooth surface, and precision. However, the effect of SLA printing parameters on the dimensional accuracy and geometric characteristics have not been studied thoroughly. This study considers an experimental approach to study the effect of SLA printing parameters such as layer thickness, build angle, support structure density, and support touchpoint size on the dimensional accuracy and geometrical characteristics of the Castable Wax printed patterns and the Al cast parts. Taguchi’s Design of Experiment was used to define the number of experimental runs. SolidCast simulation was used to design the orientation of casting feeder to achieve directional solidification. Coordinate Measuring Machine measurements of deviations in the printed and cast parts were analyzed using the “Smaller-the-better” scheme in the two-step optimization method of Taguchi experiments. Build angle and Layer thickness were identified to be the first and the second most impactful parameters, respectively, affecting both the dimensional and geometric accuracy of Castable Wax patterns and Al cast parts, with optimal values of 0 deg and 0.25 μm, respectively. Both printed and cast parts had twice as many deviations in geometry as in dimensions. The sphere roundness and angularity were found to be the most and least accurate geometric characteristics, respectively. The dimensions in the Z direction were more accurate than in the X-Y directions, showing the smallest size deviations for height measurements and large deviations in the length, width, and diameter of the hole.Item Open Access FABRICATION OF HIGHLY COMPACTED GREEN BODY USING MULTI-SIZED AL POWDER UNDER A CENTRIFUGAL FORCE(Journal of Manufacturing and Materials Processing, 2022) Sariyev, Bakytzhan; Aldabergen, Abilkhairkhan; Akzhigitov, Dulat; Golman, Boris; Spitas, ChristosThis study investigates the application of centrifugal force for the compaction of metal powder. Previous studies using the centrifugal force for manufacturing the green bodies were focused on fine powders with narrow particle size distribution or binary mixtures. This study explores the particle packing of multi-sized powder. Aluminum alloy powder with a particle size less than 100 μm and polymer binder were admixed and compacted in the centrifugal casting with ranging magnitudes of centripetal acceleration. Three different centrifugal forces were tested: 700, 1800, and 3700 G. The microstructure of the green bodies was then observed on the SEM micrographs. The obtained green bodies had high packing densities ranging from 62 to 69%. The packing density and median particle size increase at the positions further away from the center of rotation of the centrifuge with an increase of centrifugal force. The effect of centrifugal force on the segregation of particles was investigated through the quasi-binary segregation index. The segregation phenomena was not observed at 700 G, but clear particle segregation was found at higher centrifugal forces. The increase of the centrifugal force resulted in higher segregation with finer particles moving to the inner part of the spinning mold, with a significant change in the size of particles located closer to the center of rotation. Overall, the centrifugal process was found to produce highly compacted green bodies while yielding a segregation effect due to wide particle size distribution.Item Open Access OBTAINING THE DIMENSIONS AND ORIENTATION OF 2D RECTANGULAR FLAKES FROM SECTIONING EXPERIMENTS IN FLAKE COMPOSITES(Journal of Composites Science, 2022) Papathanasiou, Thanasis D.; Tsiantis, Andreas; Wang, YanweiRecently, we developed and reported the statistical validity of two methods for determining the planar aspect ratios of two-dimensional (2D) rectangular flakes in composites from the statistics of intersection lengths: one method is based on the maximum intersection length, and the other on the average intersection length. In this work, we show that these methods are valid and robust not only for flakes having isotropic, random in-plane orientations, but for the more general situations of planar orientations ranging from unidirectional (misalignment angle e = 0), to partially aligned (0 < e < p/2), to flakes of isotropic, random-in-plane orientations (e = p/2). We prove, by Monte Carlo simulations and by numerical sectioning experiments, the validity of the proposed methods for characterizing the extent of the partial alignment (the misalignment angle e) of 2D rectangular flakes in composites, based again on the statistics of the intersection lengths; this information can be obtained from cross-sections of composite samples used in optical or electron microscopy or using tomographic imaging techniques. The performance of these techniques was tested using blind experiments in numerically sectioned composites which contained up to 106 individual flakes, and was found to be very good for a wide range of flake aspect ratios.