Material extrusion (MEX) of metallic powder-based filaments has shown great potential as an additive manufacturing (AM) technology. MEX provides an easy solution as an alternative to direct additive manufacturing technologies (e.g., Selective Laser Melting, Electron Beam Melting, Direct Energy Deposition) for problematic metallic powders such as copper, essential due to its reflectivity and thermal conductivity. MEX, an indirect AM technology, consists of five steps-optimisation of mixing of metal powder, binder, and additives (feedstock); filament production; shaping from strands; debinding; sintering. The great challenge in MEX is, undoubtedly, filament manufacturing for optimal green density, and consequently the best sintered properties. The filament, to be extrudable, must accomplish at optimal powder volume concentration (CPVC) with good rheological performance, flexibility, and stiffness. In this study, a feedstock composition (similar binder, additives, and CPVC; 61 vol. %) of copper powder with three different particle powder characteristics was selected in order to highlight their role in the final product. The quality of the filaments, strands, and 3D objects was analysed by micro-CT, highlighting the influence of the different powder characteristics on the homogeneity and defects of the greens; sintered quality was also analysed regarding microstructure and hardness. The filament based on particles powder with D close to 11 µm, and straight distribution of particles size showed the best homogeneity and the lowest defects.
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http://dx.doi.org/10.3390/ma14237136 | DOI Listing |
Nanomaterials (Basel)
December 2024
School of Safety Science and Engineering (School of Emergency Management), Nanjing University of Science and Technology, Nanjing 210094, China.
To enhance the energy release of Al powder in solid propellant, ploy (difluoroaminomethyl-3-methylethoxybutane) (PDF), which has difluoroamino (NF), was utilized to improve energy and promote combustion efficiency. In this study, Al with three distinct powder sizes (29 μm, 13 μm, and 1~3 μm) was coated with PDF using the solvent/non-solvent method, leading to the formation of Al/PDF composites. The morphology and characteristics of Al/PDF were then characterized.
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January 2025
Beijing Key Laboratory of Urban Atmospheric Volatile Organic Compounds Pollution Control and Application, Beijing Municipal Research Institute of Eco-Environmental Protection, Beijing 100037, China.
To analyze the emission characteristics of VOCs from pesticide use sources in Beijing, the distribution of commonly used pesticides and dosage forms in Beijing was obtained through on-site research, and the VOC content of pesticides in different dosage forms was examined using laboratory testing methods. The emission factors of pesticide VOCs for localized dosage forms in Beijing were established, an inventory of pesticide use source VOCs was compiled, and the spatial and temporal distribution characteristics of pesticide use source VOCs were analyzed. The results indicated that ① Pesticide dosage forms were the main factors affecting the emission of VOCs from pesticides, and when accounting for VOC emissions from pesticide sources, it is necessary to know the types of pesticides and active ingredients in the target area and obtain information on pesticide dosage forms simultaneously.
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National Center for Natural Products Research, Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
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View Article and Find Full Text PDFHeliyon
December 2024
Chemistry Department, Faculty of Science, Cairo University, Giza, 12613, Egypt.
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View Article and Find Full Text PDFInt J Pharm
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Evelo Biosciences, Cambridge, MA 02139, USA. Electronic address:
Interest in oral delivery of biological drug products, commonly prepared through lyophilization, is surging. Typically, low solid content solutions are employed for lyophilization to enhance mass transfer and minimize drying time. Yet, this approach often results in lyophilized powders with low bulk density and poor flowability, challenging downstream processing steps that are required for oral product development.
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