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Cu-bearing titanium alloys exhibit promising antibacterial properties for clinical use. A novel Ti6Al4V-Ti5Cu composite alloy is developed using powder bed fusion (selective laser sintering, SLM) and spark plasma sintering (SPS). SLM produces a triple periodic minimal surface (TPMS) lattice structure from Ti6Al4V, which is then filled with Ti-5Cu powders and sintered using SPS. Microstructural analysis confirms a well-bonded interface between Ti6Al4V and Ti-5Cu could be achieved through SLM-SPS technology. The composite primarily showcases laths α phase, with Ti2Cu precipitates in the Ti-5Cu region. Electrochemical assessments reveal superior corrosion resistance in the Ti6Al4V-Ti5Cu composite compared to SLM-Ti6Al4V and SPS-Ti-5Cu. The antibacterial rate of the TPMS structure exceeds 90%, and that of TCCU-90 reaches as high as 99%, manifesting robust antibacterial activity. These findings suggest a strategy for creating biomimetic alloys that seamlessly combine structure and multifunctionality within biomedical materials. [ABSTRACT FROM AUTHOR]

Intermediate α″ phase was constructed in as-printed Ti alloys by introducing interstitial carbon atoms to mitigate the detrimental effects of α′ martensite on ductility. The interstitials served as a lattice modulation limiter to achieve an incomplete atomic shuffle during martensitic transformation process to form metastable α″ phase, followed by stabilizing the α″ to inhibit the growth of α′ martensite. The resulting microstructure, characterized by a dominant α/α′ matrix decorated with fine α″ phase, enhanced twinning formation ability and induced dynamic Hall–Petch and grain refinement strengthening effects. This resulted in simultaneous improvements in both strength and ductility.

Highlights Despite the exceptional mechanical properties of epoxy‐based carbon fiber‐reinforced plastic (CFRP), its commercial potential is limited due to high production costs and manufacturing difficulties. As a promising alternative, thermoplastic‐based CFRP (CFRTP) offers simpler manufacturing, lower cost, and recyclability. This study presents a strategy to overcome challenges for CFRTP manufacturing by using a low molecular weight (MW) thermoplastic that forms high‐MW assemblies via dynamic molecular interactions. A quadruple hydrogen‐bonding unit (UPy)‐end functional polyamide (PA‐UPy) was synthesized by simple solid‐state melt reaction of powdered mixture of PA12 and UPy‐containing isocyanate. An increase in tensile properties was observed with an increase in crystallinity by the adoption of UPy moiety. The adoption of PA‐UPy in CFRTP, prepared by simply stacking the powder and CF fabric followed by hot pressing, enhanced the composite's tensile and interlaminar properties. Therefore, this process is proposed as a simple and effective method to improve the mechanical properties of CFRTP. Synthesis of PA‐UPy achieved via solid‐state melt reaction of PA and UPy. PA supramolecular structure boosts tensile strength and modulus of films and CFRTP. UPy‐NCO doubles the interlaminar shear strength of PA‐UPy‐based CFRTP. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the ability of friction surfacing to deposit metal alloys that are difficult to process with traditional methods. Creep and neutron irradiation-resistant oxide dispersion strengthened (ODS) materials cannot be produced via the conventional casting route due to the insolubility of the oxidic and metallic alloy constituents, causing unintended inhomogeneous oxide dispersion and material behavior. Increasing the silicon content of iron-silicon (Fe-Si) improves electromagnetic properties but embrittles the material significantly, and fusion-based manufacturing methods are unable to process this steel. The solid-state nature of the friction surfacing process offers a potential alternative processing route to enable wider usage of difficult-to-process alloy systems. Both ODS and Fe-Si materials are available in powder forms. While the existing literature in friction surfacing focuses on depositing composites by incorporating small quantities of powders through holes in consumable rods, this is the first study showing that a large charge of powder can be converted to a homogeneous fully consolidated deposit in friction surfacing. A novel methodology is used that incorporates the high portion of powder feedstock into hollow consumable friction surfacing rods (up to 35% volume fraction). It was found that fully consolidated deposits can be produced with powder feedstocks using the proposed methodology. A recrystallized, homogeneous, equiaxed microstructure was observed in Fe-Si 6.8 wt% and a new-generation FeAlOY ODS alloy deposits processed with hollow stainless steel friction surfacing rods. Both powder and rod material plasticize and deposit without bulk intermixing. [ABSTRACT FROM AUTHOR]

This study fabricated (Al63Cu25Fe12)99Ce1 quasicrystal-enhanced aluminum matrix composites using the hot-pressing method to investigate their interfacial reaction traits. Microstructure analysis revealed that at 490 °C for 30 min of hot-pressing, the interface between the matrix and reinforcement was clear and intact. Chemical diffusion between the I-phase and aluminum matrix during sintering led to the formation of Al7Cu2Fe, AlFe, and AlCu phases, which, with their uniform and fine distribution, significantly enhanced the alloy's overall properties. Regarding compactness, it first increased and then decreased with different holding times, reaching a maximum of about 98.89% at 490 °C for 30 min. Mechanical property analysis showed that compressive strength initially rose and then fell with increasing sintering temperature. After 30 min at 490 °C, the reinforcement particles and matrix were tightly combined and evenly distributed, with a maximum compressive strength of around 790 MPa. Additionally, the diffusion dynamics of the transition layer were simulated. The reaction rate of the reaction layer increased with hot-pressing temperature and decreased with holding time. Selecting a lower temperature and appropriate holding time can control the reaction layer thickness to obtain composites with excellent properties. This research innovatively contributes to the preparation and property study of such composites, providing a basis for their further application. [ABSTRACT FROM AUTHOR]

Modern dry pressing of ceramic powders using spray‐dried granulates cannot avoid the occurrence of defects related to persisting inter‐ and intra‐granulate interstitial voids. These constitute the parent defect size population limiting the application of polycrystalline ceramics in high‐stress conditions. The mitigation of such defects could widen the range of application in technical and biomedical engineering, reduce the safety range for design, and extend the lifetime of components. Herein, the Weibull size‐effect on strength in size‐partitioned Yttria‐stabilized zirconias (YSZ) feedstocks is used to explore the viability of changing the density distribution of granulate sizes as an effective strategy to obtain a denser particle packing that could reduce the size distribution of strength‐limiting pressing defects. In a direct assessment of critical defect size using multiscale strength testing with a dataset of ≈1300 values, the success of such an approach in increasing the strength reliability for small volume components is demonstrated, along with its ultimate failure in altering the defect size distribution in sintered YSZ ceramics across several length scales. Finally, it is shown that granule morphology (spherical or dimpled) fails to affect the defect density and size distribution in YSZ ceramics. [ABSTRACT FROM AUTHOR]

Crystalline active pharmaceutical ingredients with comparable size and surface area can demonstrate surface anisotropy induced during crystallization or downstream unit operations such as milling. To the extent that varying surface properties impacts bulk powder properties, the final drug product performance such as stability, dissolution rates, flowability, and dispersibility can be predicted by understanding surface properties such as surface chemistry, energetics, and wettability. Here, we investigate the surface properties of different batches of Odanacatib prepared through either jet milling or fast precipitation from various solvent systems, all of which meet the particle size specification established to ensure equivalent biopharmaceutical performance. This work highlights the use of orthogonal surface techniques such as Inverse Gas Chromatography (IGC), Brunauer–Emmett–Teller (BET) surface area, contact angle, and X-ray Photoelectron Spectroscopy (XPS) to demonstrate the effect of processing history on particle surface properties to explain differences in bulk powder properties. [ABSTRACT FROM AUTHOR]

Looking back on energy over the past decade, lofty goals have been set that must be successfully met. In the field of energy in the last decade, high goals have been set, which must be successfully completed. The European Council agreed on the EU's 2030 climate and energy policy framework, setting an ambitious economy-wide domestic target to reduce greenhouse gas emissions by at least 40% by 2030. Powder processing technologies lead to increased productivity and economic efficiency, due to the reduced consumption of energy and physical work.

A facile, one-step nitridation–decomposition method was developed for the synthesis of nanosized tungsten powder with a high surface area. This approach involved the nitridation of WO3 in NH3 to form mesoporous tungsten nitride (W2N), followed by in situ decomposition of W2N to directly yield single-phase W particles. The phase and morphology evolution during the synthesis were systematically investigated and compared with the carbothermal reduction of WO3. It was revealed that powdered tungsten product with single-phase particles was obtained after nitridation at 800 °C combined with in situ decomposition at 1000 °C, displaying an average particle size of 15 nm and a large specific surface area of 6.52 m2/g. Furthermore, the proposed method avoided the limitations associated with intermediate phase formation and coarsening observed in carbothermal reduction, which resulted in the growth of W particles up to ~4.4 μm in size. This work demonstrates the potential of the nitridation–decomposition approach for the scalable and efficient synthesis of high-quality, fine-grained tungsten powder.

Sintered ore used as blast furnace burden materials is produced by mixing iron ore, coke, and limestone, then burning the coke and sintering the iron ore with the combustion heat. Among the coke charged, A particle size of 0.25 mm or less has an insignificant effect as a heat source and adhere to the surface of other materials to inhibit the reaction between oxygen and raw materials, thereby decreasing the quality of sintered ore. Therefore, to increase combustion efficiency, it is necessary to reduce the ratio of coke breeze in the charged coke. In this study, theoretical calculation, experiment and simulation were conducted to investigate the possibility of size classification by drag force in the process of dropping coke after being transported through a belt conveyor. The height of belt conveyor was at 1m, and velocity of the belt was 1.5, 2.3, and 2.6 m/s, which were considered as experimental variables. After falling, the distribution of coke particle size according to the horizontal travel distance was confirmed, and a fall trajectory prediction formula model was created through the drag model of polydisperse system and compared with the experimental and analysis results.

A facile, one-step nitridation–decomposition method was developed for the synthesis of nanosized tungsten powder with a high surface area. This approach involved the nitridation of WO3 in NH3 to form mesoporous tungsten nitride (W2N), followed by in situ decomposition of W2N to directly yield single-phase W particles. The phase and morphology evolution during the synthesis were systematically investigated and compared with the carbothermal reduction of WO3. It was revealed that powdered tungsten product with single-phase particles was obtained after nitridation at 800 °C combined with in situ decomposition at 1000 °C, displaying an average particle size of 15 nm and a large specific surface area of 6.52 m2/g. Furthermore, the proposed method avoided the limitations associated with intermediate phase formation and coarsening observed in carbothermal reduction, which resulted in the growth of W particles up to ~4.4 μm in size. This work demonstrates the potential of the nitridation–decomposition approach for the scalable and efficient synthesis of high-quality, fine-grained tungsten powder. [ABSTRACT FROM AUTHOR]

The emerging field of direct recycling for spent Li-ion batteries offers significant advantages, such as reduced energy expenses and minimized secondary pollution, when compared to traditional pyrometallurgical and hydrometallurgical methods. This is due to its direct utilization of the spent cathodes as raw materials. However, efficient harvesting of spent cathode particles remains a challenge. To address this issue, this technical brief is the first to incorporate resonant acoustic vibration technology (RAV) as an efficient method for stripping cathode powders from spent Li-ion batteries. Our findings indicate that RAV-based techniques can achieve a stripping efficiency of up to 92%. A comparative analysis with conventional stripping methods, such as magnetic stirring, sonication, and curling-uncurling, reveals that RAV coupled with heat treatment provides unparalleled scalability and efficiency, eliminating the need for post-processing. Furthermore, the resulting cathode powders retain their original polycrystalline particle structures, with no impurities, such as carbon black or small aluminum fragments detected. These findings highlight the promise of RAV technology for large-scale recovery of electrode powders and its potential role in direct recycling of spent Li-ion batteries. [ABSTRACT FROM AUTHOR]

This paper mainly deals with the current status and development trends of research on the microstructure and properties of additive manufacturing formed parts. According to the laser processes and powder processing, the microstructure of the parts including morphologies, phase composition, and grain orientation is analyzed; the forming quality of the parts including hardness, wear resistance, corrosion resistance, strength, fracture toughness, residual stresses, and fatigue properties is analyzed in many ways. At the same time, we expect to find the research directions that conform to the future development trends for LAM. [ABSTRACT FROM AUTHOR]

Looking back on energy over the past decade, lofty goals have been set that must be successfully met. In the field of energy in the last decade, high goals have been set, which must be successfully completed. The European Council agreed on the EU's 2030 climate and energy policy framework, setting an ambitious economy-wide domestic target to reduce greenhouse gas emissions by at least 40% by 2030. Powder processing technologies lead to increased productivity and economic efficiency, due to the reduced consumption of energy and physical work. [ABSTRACT FROM AUTHOR]

We introduce a paradigm of solvent and binder selection for solution-processing Li6PS5Cl solid-state electrolyte particles based on Hansen solubility parameters. Treatment of the Li6PS5Cl in selected solvents results in particle morphological change, but crystallographic structure remains intact. Although solution processing reduced the Li6PS5Cl ionic conductivity, it promotes interfacial stability by alleviating reduction of the solid electrolyte in contact with Li metal. These findings have the potential to enhance the stability, structural integrity, and performance of sulfide solid-state electrolytes in practical applications. [ABSTRACT FROM AUTHOR]

This work reports a cost-effective and environmentally friendly method for preparing high-quality and highly-crystalline silicon nitride (Si 3 N 4) powders from silicon (Si) scrap through direct nitridation. With Si scrap from semiconductor manufacturing processes being a critical and imperative global issue in recent times, an efficient methodology is essentially required to recycle it. For this purpose, ball milling parameters for Si scrap were optimized using different solvents to obtain homogeneous and fine-micron sized silicon powders for efficient nitridation. Ethanol was found to be the most effective in producing the required conditions of Si powders. Direct nitridation was performed at 1450 °C in an atmosphere of nitrogen and hydrogen gas flow to prepare Si 3 N 4 powders. Various characterization techniques were used to analyze particle sizes, phase compositions, and morphologies of raw Si scrap, ball-milled Si powders, and Si 3 N 4 powders. Results indicated that the nitridation reaction resulted in 90.1% conversion of Si into Si 3 N 4 and the α-Si 3 N 4 phase accounted for 85% of the total Si 3 N 4 produced. This study provides a fundamental perspective from both industrial and environmental standpoints on the recycle of Si waste and production of cost-effective and high-quality Si 3 N 4 powders. This novel approach of using Si scrap as a silicon source for Si 3 N 4 powder preparation has the potential to significantly reduce the large volumes of Si waste generated from semiconductor industries. [ABSTRACT FROM AUTHOR]

Solid resins (SR) are fully reactive resin systems that are solid at room temperature. Up to a critical temperature they can be quasi‐infinitely molten and solidified without any relevant curing reaction. This study deals with novel SR‐based prepregs where a dry textile is covered with a regular SR (uncured) pattern, allowing for storage and draping at room temperature. The manufacturing of SR prepregs with accurate pattern geometries and the processing of the same into laminates with a pore volume content <1% using a vacuum bag only process is demonstrated for four pattern types and two curing cycles. The study furthermore shows that the pattern design has an influence on the mandatory drying phases as well as on fiber undulations. With sufficiently long drying phases, equivalent pore volume contents and interlaminar shear strength could be obtained with different pattern types. Highlights: Manufacturing of carbon fiber (CF) solid epoxy prepregs with patterned resin distributionEpoxy powder processingOut‐of‐Autoclave manufacturing with vacuum‐bag‐only prepregsInterlaminar shear strength of carbon fiber reinforced plastics (CFRP) made of woven CFsAnalysis of pore volume content and fiber undulation [ABSTRACT FROM AUTHOR]

A novel, self-consistent model for analyzing the electromagnetic and heat-mass transfer phenomena within a conducting gas has been developed. This model, although based on well-established Maxwell's and Navier–Stokes equations, is tailored for technological powder processing plasma system. The gas is treated as compressible, and its electrical conductivity, as well as radiative losses of hot plasma, are dependent on local temperature. Maxwell's equations are reformulated into a frequency domain equation using complex values of the magnetic vector potential. This equation is further split into real and imaginary parts, resulting in a system of coupled equations, which are discretized and solved in the ANSYS Fluent using the finite volume method through the user-defined scalar and user-defined functions application programming interface in C. This model operates allows for the calculation of temporal-spatial distributions of electromagnetic fields, temperature and velocity of gas flow with particles within the torch and cooling chamber. Simulation results firstly have revealed unwanted gas-driven effects, particularly in the form of vortices downstream of the plasma tail flame. These vortices negatively impact the predictability of particle synthesis and may trap particles, preventing them from following the desired temperature history. Given the primary application of plasmatron systems in the production and processing of metal powder materials for additive manufacturing, the goal is to optimize the cooling chamber's design. This aims to promote laminar gas flow inside the chamber and prevent particle deposition on its walls, thereby minimizing material losses. The calculations performed using this developed model enable the identification of adverse gas dynamic effects during particle synthesis. Based on a series of calculations, new design solutions have been proposed to mitigate these adverse effects. This work encompasses two approaches to shape optimization: automatic adjoint-based optimization and semi-automatic optimization. By combining these methodologies, a substantial enhancement of the cooling chamber design has been achieved, reducing vortices near the chamber walls by up to . This improvement results in a more laminar tail flame, enhancing the predictability and precision of powder processing. [ABSTRACT FROM AUTHOR]

Obtaining fully dense products with high strength in one step at room temperature by powder metallurgy (PM) is generally not possible. However, doing so would reduce manufacturing and energy costs substantially. In this work, we have attempted to achieve this on commercially pure aluminum by utilizing the friction-assisted lateral extrusion process (FALEP), which has the capability of producing sheets from bulk or powder metal in a single step, by applying large shear strain. The texture, microstructure, and mechanical properties of the fully compacted powder sample were examined and compared to the bulk sheet's properties obtained also by FALEP. The powder-FALEP sample showed a smaller grain size and significantly higher strength. Simulations carried out by the Taylor-type lattice curvature-based polycrystal model shed light on the texture characteristics of the obtained materials and were in good agreement with the experiments. [ABSTRACT FROM AUTHOR]

Iron ore powder accompanied by Si-powder as a reducing agent, was melted using a high-power laser beam. During laser melting of the two different powder beds placed next to each other, silicon merged and diffused into the iron ore, forming a ternary melt phase Fe-O-Si of around 30–60–10 at%. High speed imaging of the laser melting process as well as subsequent SEM-analysis of the generated nuggets showed the formation of droplets that merge with the surrounding Si- or ore-powder and form distinct domains. Under certain circumstances, the solidifying nuggets, of the order of 0.5–5 mm in size, generated numerous small domains, up to 25 µm, of high purity iron, 90 + at%, surrounded by a matrix of the above mentioned slag. Many of these Fe-domains were created in the vicinity of regions of high Si-content.

Aluminum (Al)–aluminum–carbon nanotube (Al–CNT) dual-matrix (DM) composites are a novel class of nanocomposite materials that combine the ductility of the Al matrix with the hardness and wear resistance of the Al–CNT composite and thus can offer a unique combination of properties that make them suitable for a wide range of wear applications such as cutting tools, bearings, brake pads, wear-resistant coatings, etc. However, the specific properties of the DM Al–(Al–CNT) composite will depend on several factors related to the material's composition and the friction conditions. This study investigates the wear behavior of DM Al–(Al–CNT) composites consisting of a primary matrix of soft aluminum in which milled hard particles of (Al–CNT) are dispersed as affected by five parameters: (1) wt.% CNT in the reinforcement particles, (2) mixing ratio between the reinforcement particles and the soft Al matrix, (3) sliding speed, (4) applied load, and (5) distance. The experimental design used a Taguchi fractional factorial orthogonal array (OA) L27 to reduce the number of experiments, and analysis of variance (ANOVA) was used to determine the significance and to model the effect of each control parameter. Results showed that the wear rate could be reduced by up to 80% by tailoring the composition and controlling the friction conditions. It was found that the mixing ratio significantly impacts the wear behavior of DM Al–(Al–CNT) composites. A mixing ratio of 50% and a CNT content of 3 wt.% at the lowest applied load gave the lowest wear rate and coefficient of friction. Scanning electron microscopy investigations showed fragmentations in the reinforced matrix at higher loads and mixing ratios, which negatively impacted the wear behavior. Our findings confirm that DM Al–(Al–CNT) composites are promising for wear applications. However, the wear behavior depends on the composition and microstructural design of the composite, which needs to be carefully studied and understood. [ABSTRACT FROM AUTHOR]

Powder manufacturing processes involve a systematic processing of particulate material towards forming a final product which needs to meet specific quality standards. A means towards ensuring that standards are met in a manufacturing plant is to apply self-regulating intelligent machinery that can take mitigatory actions in the presence of a process deviation or unsatisfactory process behavior. Given a case study of an open-loop batch powder agglomeration process, this work synthesizes the process of how a feedback element can be applied towards the powder manufacturing plant in order to allow for self-regulation and process optimization which, in turn, would increase process efficiency, minimize waste and ensure that the overall product quality meets production targets. Focusing on a proposed cybernetic loop with a feedback element, a vital component is the ability to measure key quality attributes of the powder mixture, which is crucial towards ensuring the control algorithm is able to implement the most reflective and appropriate control strategy on the powder process; thus, this work discusses heavily the sensing and associated signal processing component of the cybernetic loop. The results from the reviewed signal processing scenarios which comprised the in-process material spanned estimation accuracies of 3–10%, depending on the scenario that was considered. This paper also addresses the feared dystopian view of mass redundancy and job losses in the age of the introduction of enhanced automation technology within a manufacturing process, where it is distilled what kinds of knock-on effects can be expected as a result of the technology, in addition to means by which policy makers can contribute towards ensuring that the adaptation and transition process is as smooth as possible.

Yttrium oxide has multiple applications both as a transparent material with good optical, mechanical, and thermal properties, and for photonics when doped with rare earth ions. To achieve full transparency, a careful control of the process, from the selection of powders to the final densification by sintering, is required. In this context, the characteristics of the starting powders have a great impact on the final properties. In the present work, the effect of milling conditions of two commercial Y2O3 powders on the properties of ceramics obtained by cold isostatic pressing (CIP) and vacuum sintering was investigated. The milling rate varied between 80 and 300 rpm, and the milling time between 1 and 22 h. It was found that the optimal treatment conditions are 300 rpm for 65 min, which provided a homogeneous nano-sized Y2O3 powder. IR-transparent Y2O3 ceramics obtained by a vacuum sintering have a transmittance of 78.30% (1100 nm).

Reactive binders mitigate distortion during sintering of binder jet 3D printed components by precipitating a solid phase that reinforces interparticle contacts. The present work combines experiments with micromechanical modeling to clarify how aqueous titanium bis-ammonium lactato dihydroxide (TALH), a reactive binder, affects creep and densification during sintering of binder jet printed TiO 2. TALH treatment of as-printed material results in a nanocrystalline TiO 2 overlayer that coats the micron-scale particles. At sintering temperatures, this overlayer is consumed via grain growth such that the structures of the TALH-treated and neat materials appear nearly identical. Creep rates are slower in the TALH-treated material than in the as-printed TiO 2 , but creep in the treated material is faster when compared at equivalent relative density. TALH-treated and neat TiO 2 both exhibit diffusional creep, with stress exponents near unity and activation energies of ∼400 kJ/mol. Models of structural evolution in sintering powder aggregates show that the dominant effect of TALH on the sintering mechanics is to increase the interparticle contact size, while the coordination number remains essentially unchanged. These insights are used to develop generalized guidelines for designing reactive binders to mitigate creep, quantitatively highlighting the benefits of a high solid yield from binder decomposition. [ABSTRACT FROM AUTHOR]

Defects, such as pores and cracks, can be found in parts fabricated by powder-bed additive manufacturing techniques. The origin of certain defects, such as some voids, can be linked to initial powder quality, which makes it an important factor in the process. Powders used in additive manufacturing processes are produced by different methods such as gas atomization (GA), plasma atomization (PA), and plasma rotating electrode process (PREP); each gives different powder quality. In this study, two different Al2024 powders, produced by electrode induction GA and PREP techniques, were used to investigate the effect of powder characteristics on defect formation during electron beam melting process (EBM). Powders were first characterized by using Hall flowmeter funnel and scanning electron microscope (SEM); then, the EBM process was carried out, and finally, samples were examined by density measurement using Archimedes method, SEM analysis, and tensile test. PREP powder showed higher levels of sphericity and surface smoothness without attached satellites. Consequently, a higher apparent density and decreased flowing time were achieved in PREP powder. Moreover, gas-induced internal pores were observed in GA particles. The results also revealed the average relative density of 96.7% and 99.4% for the parts built by GA and PREP powders, respectively. SEM micrographs confirmed the results of density measurement of the fabricated parts and showed higher degrees of both spherical and irregular-shaped pores in samples built by GA powder. Additionally, they showed deprived mechanical properties due to the higher porosity contents which can form stress-concentrated areas. [ABSTRACT FROM AUTHOR]

Microstructure and mechanical properties of aluminum alloy Al–10Zn–3.5Mg–2.5Cu/graphene nanoplates composites produced by ball milling and stir casting have been investigated. The presence of dispersed Graphene nano plates with high specific surface area significantly increases the strength of the composites. The microstructural studies of the alloy revealed that graphene nano plates addition reduces the grain size, but adding higher graphene nano plates content (1 wt% graphene nano plates) does not change the grain size considerably. Further investigations on tensile tests revealed that the addition of graphene nano plates increases ultimate tensile strength. Samples under T6 heat treatment (heating up to 460 °C for 8 h, quenching in water (25 °C) and aging at 120 °C for 24 h) show better strength than other samples. At higher graphene nano plates contents, the presence of graphene agglomerate on grain boundaries was found to be the favored path for crack growth. The composite containing 0.7 wt% graphene nano plates exhibits tensile strength of 582 Mpa. [ABSTRACT FROM AUTHOR]

Powder production by gas atomization of γ-TiAl based alloys typically yields a highly nonequilibrium material regarding the occurring phases and their microstructural appearance. In particular, the equilibration of the powder and the associated phase transformations during heating are of great importance for the subsequently applied densification techniques. The present work employs in situ high-energy X-ray diffraction to investigate how this thermodynamic equilibration manifests itself in the resulting phase distribution, the ordering behavior of the disordered α and β phase, both evidenced in the powder, and the change of the γ lattice parameters during heating of a Ti-46.3Al-2.2W-0.2B (at%) powder up to 850 °C. Complementary microstructural characterization of the gas-atomized powder and the heat-treated material condition reveals that the temperature exposure predominately affects the dendritic parts of the microstructure, especially when the α phase is transformed into γ phase with small embedded grains of α2 and βo. [ABSTRACT FROM AUTHOR]

Stereolithography processes such as lithography-based ceramic manufacturing (LCM) are technologies that can produce centimeter-sized structures in a reasonable time frame. However, for some parts specifications, they lack resolution. Two-photon-polymerization (2PP) ensures the highest geometric accuracy in additive manufacturing so far. Nevertheless, building up parts in sizes as large as a few millimeters or even centimeters is a time-consuming process, which makes the production of 2PP printed parts very costly. Regarding feedstock specification, the requirements for 2PP are different to those for LCM, and generally, feedstocks are designed to meet requirements for only one of these manufacturing technologies. In an attempt to fabricate highly precise ceramic components of a rather large size, it is necessary to develop a feedstock that suits both light-based technologies, taking advantage of LCM's higher productivity and 2PP's accuracy. Hybridization should bring the desired precision to the region of interest on reasonably large parts without escalating printing time and costs. In this study, specimens gained from a transparent feedstock with yttria stabilized zirconia (YSZ) particles of 5 nm at 70 wt% were presented. The resin was originally designed to suit 2PP, while being also printable with LCM. This work demonstrates how hybrid parts can be sintered into full YSZ ceramics. [ABSTRACT FROM AUTHOR]

Ni- and Co-based M-Cr-Al-Y (M = Ni and/or Co), dual phase β and γ/γ′, β--Ni-Al, γ--Ni(Co, Cr), and γ′--Ni3-Al superalloys exhibit several beneficial high-temperature (>1000 °C) (2012 °F) strength and corrosion resistance properties. Our study investigates the feasibility of fabricating a commercially available Ni-Co-Cr-AlY alloy (tradename "Amdry 386") using laser directed energy deposition (laser-DED). A significant challenge for laser fabrication of bulk Amdry 386 (A386) structures stems from the presence of relatively higher amounts of the β phase than γ/γ′ phases. While prior studies report laser fabrication of these materials in coating and cladding configurations, bulk structures have not been realized. To investigate these challenges, this study was developed to systematically evaluate the effects of modifying the A386 alloy by adding 10, 20, and 30% by weight of a Ni-20%Cr (Ni-Cr) alloy (mainly γ/γ′). Laser-DED-fabricated A386 coupons exhibited a metastable, rapidly solidified β-rich microstructure typical to laser processes. The A386 + Ni-Cr mixtures were processed using laser-DED, and small coupons from each composition were evaluated using SEM, XRD, and microhardness to characterize the as-processed microstructure. Thermodynamic modeling was performed to determine the phase evolution as a function of the alloy composition. The dominating phase switches from β to γ/γ' between the A386 and A386 + 10% Ni-Cr mixtures, but the increase in structural integrity is not observed until the Ni-Cr additions reach a minimum of 20%. Our results show that the alloy chemistry can be successfully modified to improve the structural integrity of laser-processed structures. [ABSTRACT FROM AUTHOR]

Nanocomposites with nanoparticles dispersed as the second phase have been reported to have improved mechanical properties. In spite of this potential processing methods to produce these nanocomposites are not well established. In this study, Al2O3/mullite/SiC nanocomposites were prepared by the reaction sintering of green compacts prepared by slip casting of a mixture of SiC and Al2O3 powders. Here, the surface of the SiC particles was first oxidized to produce SiO2 and to reduce the core of the SiC particles, and then the surface SiO2 was reacted with Al2O3 to produce mullite. By applying a strong magnetic field during slip casting, the Al2O3/mullite/SiC nanocomposites were fabricated with Al2O3 oriented, but not with mullite, Al2O3 was oriented so that the c-axis of the crystal was parallel to the direction of the strong magnetic field. The density was low due to the agglomeration of SiC raw powder. The bead mill using fine zirconia beads of 50 μm was effective to disperse the agglomerated particles and succeeded in obtaining high-density Al2O3/mullite/SiC with no agglomeration of SiC nanoparticles. The bending strength was greatly improved by dispersing the particles, but such improvement was not observed by texturing. [ABSTRACT FROM AUTHOR]

A Ti3C2 MXene/Ti composite powder was developed through surface modification and powder coating for producing a high-performance titanium matrix composites (TMCs) by laser power bed fusion. Introducing MXene rarely changed the original sphericity and flowability of Ti powder while it slightly enhanced the laser absorption capacity of Ti powder. The printing conditions in turn affected the morphology and distribution of MXene in as-printed composites. At optimised printing parameters, majority of MXene with high structural integrity and uniform distribution remained along the grain boundaries of as-printed composites, and a combination of high surface quality, geometrical accuracy and densification was obtained. The remaining MXene played the synergy of pulling-out effect and load transfer role, which increased the yield strength from 530 to 710 MPa, while retaining good ductility (elongation of 19.8%). Compared with ASTM standard cast Ti64 alloy, our MXene/Ti composites also exhibited superior comprehensive tensile properties and excellent strength-ductility synergy. [ABSTRACT FROM AUTHOR]

Zinc oxide has a photocatalytic activity, but in cosmetics it is used as a white pigment. When used in cosmetics, this photocatalytic activity causes some of the skin’s sebum to be broken down by the ultraviolet rays contained in sunlight. In this study, we attempted to mill zinc oxide with phosphoric acid to react the powder surface to zinc phosphate. Since zinc phosphate has no photocatalytic activity, the particles whose surface is replaced by zinc phosphate are expected to have little photocatalytic activity. The chemical composition, powder properties, photocatalytic activity, hue (visible light reflectance, L*a*b* value), and smoothness of the obtained powder materials were examined. A portion of the zinc oxide was reacted to zinc phosphate by milling with phosphoric acid. In some samples, the reaction to zinc phosphate was observed to be too advanced, resulting in larger particles. The photocatalytic activity of zinc oxide was successfully eliminated through milling. Although the samples in this study had sufficient whiteness, the whiteness of some of the samples decreased due to contamination by milling. The smoothness of the pigment powders produced in this study was improved by milling, especially by prolonged treatment and the use of low concentrations of phosphoric acid.

Microstructural, physical and mechanical properties of Al–20 wt% Si matrix alloy powders and those reinforced with TiB2 and their sintered composites were investigated in relation to TiB2 content and mechanical alloying (MA) durations. Al–20 wt% Si matrix alloy powders and those containing 5 and 10 wt% TiB2 reinforcing particles were MA’d for 1, 2, 4, and 8 h followed by consolidation and sintering at 843 K. Si solubility in a-Al matrix increased with increasing MA duration. Increasing the TiB2 content, on the other hand, resulted in a systematic drop in Si solubility over the same MA period. Scanning electron micrographs of the sintered samples revealed sub-micron-sized, rod-shaped Si and spherical Al9Si phase particles. With increasing TiB2 content and MA durations, the microhardness of the Al20Si/TiB2 composites improved. The wear resistances of TiB2 reinforced composites better by 5 to 8 times than that of the as-blended and 1 h MA’d AlSi matrix alloy. Due to the presence of the Al3Ti intermetallic phase, sintered composite samples containing 10 wt% TiB2 particles MA'd for 8 h had the maximum hardness value and lower wear resistance values than those of the Al–20 wt% Si/5 wt% TiB2 composites.

Particle packing densification due to vibrations is a common process that occurs in many industrial applications and is beneficial for achieving better mechanical properties in powder metallurgy. However, most of the research up to this point was focused on vibration compaction of uniform-sized or binary particle mixtures, while most actual commercial powders consist of particles of variable sizes. In this work, the packing of multi-sized sphere mixtures under horizontal vibrations is simulated with the help of the discrete element method (DEM). The variations of total and local packing density with vibrations and particle size were investigated. The simulation results suggest that there are optimal values for the two vibration parameters at which the closest packing is obtained. Further increase in the particle size decreases the density and slightly shifts these peaks to the lower values of vibrations. Local density values are quite uniform at the optimal vibration parameters, but the deviations become higher when frequency or amplitude is too low or high. With an increase in particle size, these trends become less profound and more deviated. The investigations of effects of size can help in predicting optimal parameters and density values for experimental studies. These developments are similar to those for uniform and binary particle assemblies and correlate with experimental and numerical studies from the literature. The results can be helpful in carefully choosing the particle mixture properties and vibration conditions for actual manufacturing. [ABSTRACT FROM AUTHOR]

The efficiency of powder-based directed energy deposition (DED) nozzle is dependent on its ability to direct the pneumatically conveyed powder into the meltpool. Computational fluid dynamics (CFD) with discrete phase modeling (DPM) has been used to investigate the optimization of DED nozzle geometry and DED parameter selection, however, the effect of material choice for nozzle fabrication has not been fully investigated. To explore the effects of the nozzle material on powder efficiency a CFD DPM model was created and analyzed in ansys fluent. Various nozzle materials were simulated using statistical models for the coefficient of restitution (COR) between the powder and nozzle wall from the literature. The results of the CFD DPM model aligned well with experimental data for a 316L stainless steel prototype nozzle. CFD DPM results indicated that using a material with a lower mean COR value improved the powder efficiency of the nozzle. Powder efficiency improved because the component of powder velocity normal to the direction of gas flow was reduced in nozzles made from materials with lower COR values, which in turn led to fewer impacts between the particles and the nozzle walls. [ABSTRACT FROM AUTHOR]

Cold spray is an advanced 3D technique to build thick coatings using ductile powders. Plastic deformations and physical interactions induced by kinetic energy are mainly the origins of interparticle and particle–substrate adhesion. The deposition efficiency, i.e., the quantity of matter deposited compared to the amount propelled, is directly linked to the parameters used in the cold spray. To improve this aspect, parameters' optimization is also required with other solutions such as using thermally treated powders or powder blending with hard particles. Another approach is recycling powder, though it has not yet been widely evaluated. When depositing a blend of fresh and recycled Sn powder, the results showed improved coating deposition efficiency compared to a batch of 100% fresh or recycled particles. This blend does not significantly change the coating thickness, although it decreases the porosity ratio because of the thermal–mechanical history of the recycled particles. Recycled particles present lower elastic modulus. Finally, coating/substrate adhesion force was unchanged for the blend of fresh and recycled particles, but this still depends on the nature of the powder used. [ABSTRACT FROM AUTHOR]

Powder manufacturing processes involve a systematic processing of particulate material towards forming a final product which needs to meet specific quality standards. A means towards ensuring that standards are met in a manufacturing plant is to apply self-regulating intelligent machinery that can take mitigatory actions in the presence of a process deviation or unsatisfactory process behavior. Given a case study of an open-loop batch powder agglomeration process, this work synthesizes the process of how a feedback element can be applied towards the powder manufacturing plant in order to allow for self-regulation and process optimization which, in turn, would increase process efficiency, minimize waste and ensure that the overall product quality meets production targets. Focusing on a proposed cybernetic loop with a feedback element, a vital component is the ability to measure key quality attributes of the powder mixture, which is crucial towards ensuring the control algorithm is able to implement the most reflective and appropriate control strategy on the powder process; thus, this work discusses heavily the sensing and associated signal processing component of the cybernetic loop. The results from the reviewed signal processing scenarios which comprised the in-process material spanned estimation accuracies of 3–10%, depending on the scenario that was considered. This paper also addresses the feared dystopian view of mass redundancy and job losses in the age of the introduction of enhanced automation technology within a manufacturing process, where it is distilled what kinds of knock-on effects can be expected as a result of the technology, in addition to means by which policy makers can contribute towards ensuring that the adaptation and transition process is as smooth as possible. [ABSTRACT FROM AUTHOR]

The implantation of stents and instruments with capillary action demands super-finished internal surfaces of the manufactured product. Elasto-abrasives magneto-spiral finishing (EAMSF) is the attempt made in this paper to enhance finishing productivity by incorporating the abrasive flow in spiral motion due to the presence of the magnetic field. Here, novel impregnated elasto-magnetic abrasive particles (IMPs) are used in a magnetic field-assisted environment to polish the inner walls of the workpiece. In EAMSF, magnetic force provides excess finishing pressure to the abrasives. In contrast, the high-impact polystyrene (HIPS) elasticity absorbs the extra force of the IMPs on the finishing surface. An Indigenous mathematical relation considering the physics of this superfinishing process indicating material removal shows a close resemblance to the experimental results with an error percentage of 1.03 has been developed. The results of the experimentation reveal that 50% concentration of abrasives and a magnetic field density of 18mT yield a superior surface finish with a Ra value equal to 0.053 µm and maximum material removal of 6.9 mg, while in the absence of a magnetic field, excellent surface finish with a Ra = 0.266 µm and maximum material removal of 5.4 mg is achieved. In the presence of magnetic field density, significant enhancement of material removal, surface finish, and burr removal is observed. Finishing the surface at 50% abrasive concentration with a magnetic field represents regular finishing, and the trench marks on the original surface are removed after finishing. [ABSTRACT FROM AUTHOR]

Aluminium alloys (AA) are ubiquitous materials in manufacturing used in powder bed fusion (PBF) processes due to light weight, high strength and corrosion resistance. Current research focuses on other materials whilst additively manufactured AA 7050 remains unexplored. This paper examines the formability of AA 7050-T7451 powder for the Selective Laser Melting (SLM) process. To define this material in Simufact AdditiveTM the creep behaviour required flow curves obtained by writing a MATLAB® script to calculate the true stress–strain behaviour depending on strain rate and temperature. The results of the mechanical calibration for aluminium alloy are presented to obtain its inherent strains. [ABSTRACT FROM AUTHOR]