Artículos de revistas sobre el tema "Powder"
Siga este enlace para ver otros tipos de publicaciones sobre el tema: Powder.
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores artículos de revistas para su investigación sobre el tema "Powder".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore artículos de revistas sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Lange, Gerrie. "Vortex Target: A New Design for a Powder-in-Gas Target for Large-Scale Radionuclide Production". Instruments 3, n.º 2 (3 de abril de 2019): 24. http://dx.doi.org/10.3390/instruments3020024.
Texto completoResumen
This paper presents a design and working principle for a combined powder-in-gas target. The excellent surface-to-volume ratio of micrometer-sized powder particles injected into a forced carrier-gas-driven environment provides optimal beam power-induced heat relief. Finely dispersed powders can be controlled by a combined pump-driven inward-spiraling gas flow and a fan structure in the center. Known proton-induced nuclear reactions on isotopically enriched materials such as 68Zn and 100Mo were taken into account to be conceptually remodeled as a powder-in-gas target assembly, which was compared to thick target designs. The small irradiation chambers that were modeled in our studies for powdery ‘thick’ targets with a mass thickness (g/cm2) comparable to 68Zn and 100Mo resulted in the need to load 2.5 and 12.6 grams of the isotopically enriched target material, respectively, into a convective 7-bar pressured helium cooling circuit for irradiation, with ion currents and entrance energies of 0.8 (13 MeV) and 2 mA (20 MeV), respectively. Current densities of ~2 μA/mm2 (20 MeV), induces power loads of up to 4 kW/cm2. Moreover, the design work showed that this powder-in-gas target concept could potentially be applied to other radionuclide production routes that involve powdery starting materials. Although the modeling work showed good convective heat relief expectations for micrometer-sized powder, more detailed mathematical investigation on the powder-in-gas target restrictions, electrostatic behavior, and erosion effects during irradiation are required for developing a real prototype assembly.
2
Field, A. C., L. N. Carter, N. J. E. Adkins, M. M. Attallah, M. J. Gorley y M. Strangwood. "The Effect of Powder Characteristics on Build Quality of High-Purity Tungsten Produced via Laser Powder Bed Fusion (LPBF)". Metallurgical and Materials Transactions A 51, n.º 3 (1 de enero de 2020): 1367–78. http://dx.doi.org/10.1007/s11661-019-05601-6.
Texto completoResumen
AbstractTwo high-purity tungsten powders, produced via different manufacturing techniques, were characterized to determine size distribution, morphology, thermal properties, and flow characteristics and, thus, the likely suitability for Laser Powder Bed Fusion (LPBF) production. Specimens from duplicate builds were produced with the two powders and characterized for density, defect mechanisms, and thermal penetration into the substrate plate to compare apparent power densities. The first powder was a chemically reduced powder with irregular morphology and the second, a plasma spheroidized powder with highly spherical morphology. The latter was found to have tighter morphological control and size distribution, having a third of particles at the modal particle size in comparison to a fifth of the chemically reduced powder. This led to better flow characteristics, and an increase of 1.5 g cm−3 (1500 kg m−3) in the packing densities seen in the powder bed which corresponds to 57 pct theoretical density vs 50 pct theoretical density in the chemically reduced powder. As a result, the specimens produced from the plasma spheroidized powder had higher densities (97.3 vs 88.5 pct) and the dominant defect mechanism moved from lack of fusion dominated in the chemically reduced powder to cracking dominated in the plasma spheroidized. The plasma spheroidized powder also showed higher apparent power densities (effective absorptivities) as evidenced by an 80 pct deeper penetration of the laser into the substrate plate.
3
Govender, Preyin, Deborah Clare Blaine y Natasha Sacks. "INFLUENCE OF POWDER CHARACTERISTICS ON THE SPREADABILITY OF PRE-ALLOYED TUNGSTEN- CARBIDE COBALT". South African Journal of Industrial Engineering 32, n.º 3 (2021): 284–89. http://dx.doi.org/10.7166/32-3-2664.
Texto completoResumen
With rising interest in additive manufacturing (AM) techniques, there is an increased focus on research that evaluates critical parameters that guide the selection of powders that are suitable for AM. One such parameter is a powder’s spreadability, described by metrics such as powder bed density and percentage coverage. This study focused on three spray-dried WC-Co powders (two 12 wt% and one 17 wt% Co) and evaluated the influence of typical powder characteristics, such as particle size and shape, apparent density, and flow rate, on their spreadability. It was found that particle size distribution influenced the powder spreadability. Larger particles hindered the even spreading of powder over the base plate, resulting in low powder bed density and percentage coverage. This also correlated with the powders’ apparent densities. The flow rate and angle of repose gave an indication of how cohesive the powders are. The more cohesive a powder, the poorer the spreadability, resulting in a lower powder bed density and percentage coverage.
4
Lu, Yingying, Kai Ma, Changchao Guo, Ming Jiang, Chengfeng Wu, Shipeng Li y Shaoqing Hu. "Experimental Studies on Thermal Oxidation and Laser Ignition Properties of Al-Mg-Li Powders". Materials 16, n.º 21 (28 de octubre de 2023): 6931. http://dx.doi.org/10.3390/ma16216931.
Texto completoResumen
Powder ramjets are a kind of vehicle propulsion system with high specific impulse and efficiency. They provide significant benefits in terms of extended propulsion and thrust adjustment. The pursuit of a highly reactive fuel appropriate for powder ramjets is likely to stimulate advancements in innovative propulsion systems, which are crucial for deep space exploration and long-term space missions. This work presents experimental studies on the thermal oxidation and laser ignition performance of aluminum–magnesium–lithium powders at atmospheric pressure. TG-DSC curves of powders in three heating rates were obtained. The ignition processes and ignition delay times were recorded by a CO2 laser ignition experiment system at a laser power of 10~60 W. The results show that at a lower heating rate of 10 K/min, the powder’s thermal hysteresis is less, and the powder energy released in stage I is more concentrated. However, the degree of heat release concentration approached a similar level at heating rates of 30 K and 50 K. The ignition delay time decreased as the laser flux density increased. When the laser flux density exceeds 80 W/cm2, the effect of laser power on the ignition delay time decreases. At atmospheric pressure, the mathematical relationship between ignition delay time and laser flux density is given. Finally, the powder ignition processes at different laser powers are represented graphically.
5
Çalışkan Koç, Gülşah y Ayşe Nur Yüksel. "THE FOAM-MAT CONVECTIVE AND MICROWAVE DRIED AVOCADO POWDER: PHYSICAL, FUNCTIONAL, AND POWDER PROPERTIES". Latin American Applied Research - An international journal 50, n.º 4 (25 de septiembre de 2020): 291–97. http://dx.doi.org/10.52292/j.laar.2020.486.
Texto completoResumen
The aim of this study was to produce hot air (60-80°C and 20% ventilation rate) and microwave (120-700W) assisted foam mat dried avocado powders and to determine the effect of different drying temperatures and microwave powers on physical, functional, and powder properties of avocado powders. Significantly lower drying times were observed for the microwave assisted foam-mat dried avocado powder (p<0.05). Microwave assisted foam-mat dried avocado powders have superior properties in moisture content and flow properties (p<0.05), whereas comparatively better results were obtained for hot air assisted foam mat dried avocado powder for wettability and solubility times. The changes in ash content, pH, water holding capacity, bulk and tapped densities, Carr Index and Hausner Ratio values followed a quadratic trend depending on both drying temperature and microwave power. Principal component analysis indicated that there is a convenient relation between the avocado powders which were dried at different drying techniques and conditions.
6
Zhou, Feng, Ying Qing Fu y Yang Gao. "Properties of Al2O3-TiO2 Coating Prepared by Plasma Spraying with an Internally-Fed Powder System". Key Engineering Materials 368-372 (febrero de 2008): 1274–76. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.1274.
Texto completoResumen
Alumina-titania (60: 40 by weight) coatings were prepared by low power plasma thermal spraying with two types of plasma spray systems: internally-fed and externally-fed powder system. The coatings were investigated by many techniques, respectively X-ray diffraction (XRD), scanning electron microscopy (SEM) and micro-hardness tester. It was found that the thickness of coatings by low power plasma spray with an internally-fed powder system is higher than that of the coatings with an externally-fed powder system. The internally-fed powder system not only decreases the loss of powder but also increases the deposition efficiency for more than 80%. To better qualify the characteristics of these coatings prepared from spray-dried powders, microhardness was also studied.
7
Nakamura, Takahiro, Hajime Horikawa, Masahiro Asahara, Xing Zheng Wu y Takashi Ogihara. "Dye-Sensitized Solar Cell Fabrication with Hydrothermal Synthesized TiO2 and Evaluation the Power Generation Efficiency". Key Engineering Materials 388 (septiembre de 2008): 293–96. http://dx.doi.org/10.4028/www.scientific.net/kem.388.293.
Texto completoResumen
TiO2 powder was synthesized hydrothermally from titanium alkoxide ethanol solution in supercritical state and obtained anatase type crystalline powder sized ca. 20 nm. Dye-sensitized solar cells were fabricated with the powders and evaluated the power generation efficiencies.
8
Sehhat, M. Hossein, Austin T. Sutton, Chia-Hung Hung, Ben Brown, Ronald J. O’Malley, Jonghyun Park y Ming C. Leu. "Plasma spheroidization of gas-atomized 304L stainless steel powder for laser powder bed fusion process". Materials Science in Additive Manufacturing 1, n.º 1 (18 de marzo de 2022): 1. http://dx.doi.org/10.18063/msam.v1i1.1.
Texto completoResumen
Particles of AISI 304L stainless steel powder were spheroidized by the induction plasma spheroidization process (TekSphero-15 spheroidization system) to assess the effects of the spheroidization process on powder and part properties. The morphology of both as-received and spheroidized powders was characterized by measuring particle size and shape distribution. The chemistry of powders was studied using inductively coupled plasma optical emission spectroscopy for evaluation of composing elements, and the powder’s microstructure was assessed by X-ray diffraction for phase identification and by electron backscattered diffraction patterns for crystallography characterization. The Revolution Powder Analyzer was used to quantify powder flowability. The mechanical properties of parts fabricated with as-received and spheroidized powders using laser powder bed fusion process were measured and compared. Our experimental results showed that the fabricated parts with plasma spheroidized powder have lower tensile strength but higher ductility. Considerable changes in powder chemistry and microstructure were observed due to the change in solidification mode after the spheroidization process. The spheroidized powder solidified in the austenite-to-ferrite solidification mode due to the loss of carbon, nitrogen, and oxygen. In contrast, the as-received powder solidified in the ferrite-to-austenite solidification mode. This change in solidification mode impacted the components made with spheroidized powder to have lower tensile strength but higher ductility.
9
Gorji, N. E., R. O’Connor y D. Brabazon. "XPS, SEM, AFM, and Nano-Indentation characterization for powder recycling within additive manufacturing process". IOP Conference Series: Materials Science and Engineering 1182, n.º 1 (1 de octubre de 2021): 012025. http://dx.doi.org/10.1088/1757-899x/1182/1/012025.
Texto completoResumen
Abstract Powder recycling and reducing the waste metallic powder is EU’s key provision in waste framework directive (2008/98/EC). The aim of this investigation is to analyse the correlation between the surface and morphology properties of (virgin and recycled) powders and the microstructure and mechanical properties of the 3D printed parts (made of three powders). Two biomedical Tibia implants have been 3D printed from virgin and 3-5 times recycled powders of stainless steel 316L. For this, the surface composition and microstructure of the powders has been characterized and correlated to the nanoindentation measurements carrier out on these implants. X-ray surface spectroscopy (XPS) has been used to analyse the oxidation level on the powder’s surface revealing less than 10% more oxygen on the surface of recycled powders. SEM analysis shows less than 5 μm difference in powder size distribution even though the shape and circularity of the recycled powders seem to be affected under several reusing cycles. The size of the powder particles does not show much difference but satellites and binding between the powders increased in recycled powder. The hardness and effective modulus of the parts from recycled powders are significantly smaller than the virgin-made implants, which could be due to higher porosity present in the recycled powder or due to oxygen increment on recycled powder. The surface roughness (AFM analysis) has slightly increased on part made of recycled powders. However, the overall morphology shows little difference between the two parts.
10
Ozerskoi, Nikolai, Alexey Silin, Nikolay Razumov y Anatoly Popovich. "Optimization of EI961 steel spheroidization process for subsequent use in additive manufacturing: Effect of plasma treatment on the properties of EI961 powder". REVIEWS ON ADVANCED MATERIALS SCIENCE 60, n.º 1 (1 de enero de 2021): 936–45. http://dx.doi.org/10.1515/rams-2021-0078.
Texto completoResumen
Abstract For use in additive manufacturing (AM), powders that have a spherical shape, high fluidity, and packing density are required. One of the methods for producing spherical powders is spheroidization using inductively coupled plasma. In this work, the powder of steel grade EI961 was used. To obtain the powder for subsequent use in 3D printing, the selection of modes was carried out with the change in various parameters of the unit: different power, powder feed rate to the plasma as well as the height of feed rate. The optimal spheroidization mode is as follows: power of 15 kW, pressure of 1 atm, feed rate height of 0 mm, and powder feed rate of 28 g·min−1. The temperature distribution over the plasma torch cross section was calculated and the maximum plasma temperature was also determined. In addition, the effect of plasma treatment on the granulometric composition, phase composition, and chemical composition was studied.
11
Park, Sung-hun, So-yeong Lee, Ho-seong Lee y Ho-sang Son. "The production of Titanium Powder via Hydrogen Reduction of Titanium Tetrachloride by Inductively Coupled RF plasma". MATEC Web of Conferences 321 (2020): 07011. http://dx.doi.org/10.1051/matecconf/202032107011.
Texto completoResumen
In this study, the production of titanium powder via hydrogen reduction of titanium tetrachloride by inductively coupled radio frequency plasma was investigated. While titanium tetrachloride is hard to be reduced by hydrogen thermodynamically, dissociated hydrogen radical which formed from hydrogen gas passing through the plasma can react with titanium tetrachloride to form hydrochloric acid and subsequently produce titanium. The frequency of generator used in this experiment was 13.56 MHz and input power was varied. The characteristics of the powder such as powder size, size distribution, and phases were analyzed with x-ray diffractometer, field emission scanning electron microscope, energy dispersive x-ray spectrometer and transmission electron microscope. The deposited height of titanium powders, after 4 minutes reaction, were 4.004 μm and loosely attached that could be easily collected. The morphology of powders was found to be more spherical with the increase in applied input power. Most of the powders were composed of titanium and oxygen. The average diameter of powders was approximately 200 nm.
12
Hassanuddin, Nik, Mariyam Jameelah Ghazali, Andanastuti Muchtar, M. C. Isa y Abdul Razak Daud. "Effects of Al2O3-13% TiO2 Coating Particle Size on Commercial Mild Steel via Plasma Spray Method". Key Engineering Materials 462-463 (enero de 2011): 645–50. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.645.
Texto completoResumen
This paper discusses the effect of Al2O3-13% TiO2 agglomerated nanoparticle powders ranging from 20 to 60 m and microparticle powders ranging from 10 to 25 m on commercial marine grade mild steels using a plasma spray technique. Prior to coating, the nanoparticle powders were subjected to a 2 level factorial design of experiment to give a careful control and optimise the operational spray parameters as well as process by using the statistical methods. The method was focused on the primary gas pressure, carrier gas pressure and powder feed rate of the spray parameters. The optimum properties of wear rate, surface roughness and microhardness were identified by using the lowest primary and carrier gas pressure together with the highest powder feed rate. As for the microparticle powders, they were subjected to an optimum properties by using 35 kW plasma spray power. In this study, the plasma spray power for microparticle varied from 20 kW to 40 kW, while the other parameters such as primary gas pressure, carrier gas pressure, powder feed rate and spray distance were held constant. It was found that microparticle powders exhibited denser coating microstructure s and improved both surface roughness and microhardness. On the other hand, the nanoparticle powder coating gave a greater wear resistance than those of micro particle powders, which may likely due to the strengthening effect of both fully and partially melted region.
13
ADACHI, Kyoushi. "Development of Powder Lubricant for Compacting Raw Material Powders in Powder Metallurgy". Journal of the Japan Society of Powder and Powder Metallurgy 68, n.º 1 (15 de enero de 2021): 8–19. http://dx.doi.org/10.2497/jjspm.68.8.
Texto completo
14
Li, Lang, Liyi Xu, Marshall Shuai Yang, Jinbao Huang, Hui Zhang y Jesse Zhu. "A Novel Method to Formulate Pigmented Powder Coatings by Ultrafine Powders". Powders 1, n.º 4 (17 de noviembre de 2022): 221–30. http://dx.doi.org/10.3390/powders1040015.
Texto completoResumen
Powder coatings are a green alternative to conventional solvent-borne liquid coatings, but they have the intrinsic drawback of color-matching and adjustment in production with the conventional extrusion process. In this study, an industrially applicable approach to formulate color powder coatings utilizing ultrafine powders, i.e., a powdery blending and pressing method, was invented. This novel method was validated by comparing samples prepared by the Method 1 conventional extrusion method with an extra ultramarine pigment at 3%; Method 2 powdery blending and pressing of the original coatings and the same coating with 6% ultramarine pigment utilizing regular (coarse) powder coatings; and Method 3 utilizing ultrafine powder coatings for the two coatings with the same formulations as Method 2. The coating powders were prepared to have similar particle sizes and particle size distributions, with three commonly used coating binders, namely polyester-epoxy hybrid, polyester/TGIC (triglycidyl isocyanurate), and polyurethane (PU). The powders prepared by Methods 1 and 3 had similar flow abilities in terms of angle of repose (AOR) and avalanche angle (AVA). The performance of the new coatings by Method 3 was close to or better than the ones prepared by Method 1 in terms of the specular gloss, DOI (distinctness-of-image), reflection haze and color values, being superior to Method 2. The coatings via ultrafine powders also exhibited a comparable ultramarine particle distribution in the coating cross-sections as the conventional ones, whereas the ones via regular powders had an inferior pigment dispersion. The new method can greatly enhance the production efficiency and reduce the cost of powder coatings with compound colors, especially for small batch manufacturing.
15
Messina, Gaglio, Morghese, Tolone, Arena, Moschetti, Santulli, Francesca y Settanni. "Microbiological Profile and Bioactive Properties of Insect Powders Used in Food and Feed Formulations". Foods 8, n.º 9 (9 de septiembre de 2019): 400. http://dx.doi.org/10.3390/foods8090400.
Texto completoResumen
Microbiological, nutritional and bioactive properties of edible powders obtained from Acheta domesticus (house cricket) and Tenebrio molitor (mealworm) were investigated. Except for the enterobacteria, viable bacteria were at a higher concentration in mealworm flour. The diversity evaluation carried out using MiSeq Illumina that mainly identified Citrobacter and Enterobacteriaceae in mealworm powder and members of the Porphyromonadaceae family in house cricket powder. Enterococci were identified and characterized for their safety characteristics in terms of the absence of antibiotic resistance and virulence. Both powders represent a good source of proteins and lipids. The fatty acid profile of mealworm powder was characterized by the predominance of the monounsaturated fatty acids and house cricket powder by saturated fatty acids. The enzymatic hydrolysis produced the best results in terms of percentage of degree of hydrolysis with the enzyme Alcalase, and these data were confirmed by SDS-PAGE electrophoresis. Furthermore, the results showed that the protein hydrolysate of these powders produces a significant antioxidant power.
16
Anilkumar, V., R. Kalyani, B. Padmasri y D. Prasanth. "In-house preparation, development and evaluation of herbal cosmetics face pack using various natural powders". Journal of Drug Delivery and Therapeutics 10, n.º 5 (15 de septiembre de 2020): 159–64. http://dx.doi.org/10.22270/jddt.v10i5.4314.
Texto completoResumen
An eco- friendly product has been the primary agenda of 21st century of the global scientists. Herbal cosmetics have growing demand in the global market. The aim of present work is to In-house preparation, development and evaluation of herbal cosmetics face pack using various natural powders for glowing skin by using natural Ingredients. The natural powders used are shade dried commercial turmeric, rice flour, gram flour, rose powder, tomato powder, orange peel powder. Sandalwood powder, milk powder, camphor powder were purchased form local market in the form of dried powder, all powdered natural ingredients were sieved using #120 mesh, weighed accurately and mixed geometrically for uniform preparation and evaluated for parameters including macroscopical, Physiochemical, irritancy, antimicrobial tests along with stability studies. Thus, in this work we formulate herbal face pack by using easily available ingredients. After evaluation, we found good flow properties, free from skin irritation and maintained proper stability storage conditions. Results of this study scientifically verified that herbal face pack having enough potential to give efficient glowing effect on skin. The overall study is useful to substantiate product claims due to its benefits on the human being.
Keywords: herbal cosmetics, turmeric, Sandalwood powder, orange peel powder
17
KUROKI, Hidenori. "Powder Metallurgy or Baked Metal Powders". Journal of the Society of Mechanical Engineers 110, n.º 1060 (2007): 186–87. http://dx.doi.org/10.1299/jsmemag.110.1060_186.
Texto completo
18
Champion, Y. "Powder metallurgy of nanometric aluminium powders". Powder Metallurgy 51, n.º 2 (junio de 2008): 125–32. http://dx.doi.org/10.1179/174329008x284912.
Texto completo
19
Hu, J., J. Zhao y J. J. Ren. "Solid state batteries (SSBs) prepared with powder metallurgy route". Science of Sintering 45, n.º 2 (2013): 149–55. http://dx.doi.org/10.2298/sos1302149h.
Texto completoResumen
The solid state batteries (SSBs) were prepared by powder metallurgy route. For making SSBs, a special die was designed. LiNiO2 and face centre cubic (fcc) TiB powders [1] were used to make cathodes for SSBs while such metals as Zn or Mg were used to make anodes. The SSBs made with LiNiO2 powder generated relatively low currents (1 to 2 ?A) and voltage (0.4~0.9 V) at room temperature. The SSBs made with fcc-TiB cathode generated more power than do the SSBs made with LiNiO2 powder.
20
Dire, RM, H. Bissett, D. Delport y K. Premlall. "Characterisation of Spheroidised tungsten carbide metco 32c powder using radio frequency plasma". Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 40, n.º 1 (24 de enero de 2022): 113–17. http://dx.doi.org/10.36303/satnt.2021cosaami.22.
Texto completoResumen
Metco 32C is a coarse grey powder, which mostly consists of tungsten carbide and cobalt; with small traces of nickel, chromium, boron, iron silicon and carbon. Metco 32C powder has the role of supporting oxidation and corrosion resistance at high temperatures as well as increasing the hardness of the coated materials. The spheroidal morphology of Metco 32C improves flowability during layer application methods such thermal spraying. There has been a growing interest in the development / improvement of methods producing powders of cast tungsten carbide and other high-melting-point materials of uniform composition, characterised by a high sphericity of the particles and having higher physical-mechanical properties. Spherical particles are generally preferred in the additive manufacturing process as they pack together for uniform powder bed density, better flowability in machinery, eliminate internal cavities and fractures resulting in a better quality of final product. Similarly, thermal spraying processes also require dense, spherical particles to ensure consistency and reproducibility of the feeding mechanism as well as interaction between the feedstock and thermal spraying heat source. The process of transforming irregularly shaped powder particles into spherical shapes is known as the spheroidisation process and this can be achieved by plasma spheroidisation. It was found that the spheroidisation ratio of the powder increased as the plasma plate power increased. A decrease in density was observed as plasma power increased. The spheroidised powders have a smaller particle size distribution (PSD) than the feed powders (un-spheroidised). The XRD results showed that as the plasma plate power increased the WC phase composition decreased, subsequently the phase composition of W2C increased.
21
Yu, Yue Qiang, Yan Ling Guo y Kai Yi Jiang. "Temperature Field Simulation of Wood Powder/PES Composite Powder Material". Key Engineering Materials 667 (octubre de 2015): 218–23. http://dx.doi.org/10.4028/www.scientific.net/kem.667.218.
Texto completoResumen
In view of the physical process of the wood powder/PES composite powder material selective laser sintering forming ,this article establishes the plane moving Gaussian heat source as the input laser heat source model .Based on selective laser sintering wood powder/PES composite powder sintering theory and combined with thermal conductivity of composite powder, specific heat, density and other related theoretical analytical models .It establishes three dimensional finite element model of selective laser sintering process of wood powder/PES composite powder transient temperature field .The laser sintering simulation experiment of wood powder/PES composite powder under different laser power obtains temperature field distribution law of the wood powder/PES composite powder forming under different laser power distribution, and the influence of the forming parts forming quality of wood powder/PES composite powder materials caused by the temperature field. The simulation results also provide certain theoretical basis for the choice of laser power in the subsequent laser sintering experiment.
22
Percival, W., H. Pollock y A. Smith. "Power inductors made by powder metallurgy". IEEE Transactions on Magnetics 22, n.º 6 (noviembre de 1986): 1868–75. http://dx.doi.org/10.1109/tmag.1986.1064698.
Texto completo
23
Alkahari, Mohd Rizal, Tatsuaki Furumoto, Takashi Ueda y Akira Hosokawa. "Melt Pool and Single Track Formation in Selective Laser Sintering/Selective Laser Melting". Advanced Materials Research 933 (mayo de 2014): 196–201. http://dx.doi.org/10.4028/www.scientific.net/amr.933.196.
Texto completoResumen
Selective Laser Sintering/Selective Laser Melting (SLS/SLM) is one of Additive Manufacturing (AM) processes that utilize layer by layer powder deposition technique and successive laser beam irradiation based on Computer Aided Design (CAD) data. During laser irradiation on metal powders, melt pool was formed, which then solidified to consolidated structure. Therefore, melt pool is an important behavior that affects the final quality of track formation. The study investigates the melt pool behavior through visualization of the consolidation process during the single track formation on the first layer. In order to understand the transformation process of metal powder to consolidated structure and mechanism involved, high speed camera was used to monitor the process. Yb:fiber laser beam was irradiated on metal powder at maximum power of 150W. The laser processing parameters such as laser power, scan speed and layer thickness were varied in order to investigate their influence on the consolidation process. The result shows the size of melt pool increased with laser power and decreasing with increment in scan speed. Furthermore, with the increase of layer thickness, melt pool formation was unstable with chaotic movement. Significant amount of molten powder splattering was recorded from the melt pool. At high layer thickness also, the molten powder formed spherical shaped and the solidified molten powder failed to wet with the substrate.
24
Qi, Hang, Xianglin Zhou, Jinghao Li, Yunfei Hu y Lianghui Xu. "Performance Testing and Rapid Solidification Behavior of Stainless Steel Powders Prepared by Gas Atomization". Materials 14, n.º 18 (9 de septiembre de 2021): 5188. http://dx.doi.org/10.3390/ma14185188.
Texto completoResumen
Gas atomization is a widely used method to produce the raw powder materials for additive manufacturing (AM) usage. After the metal alloy is melted to fusion, gas atomization involves two relatively independent processes: liquid breakup and droplet solidification. In this paper, the solidification behavior of powder during solidification is analyzed by testing the powder’s properties and observing microstructure of a martensitic stainless steel (FeCrNiBSiNb). The powder prepared by gas atomization has high sphericity and smooth surface, and the yield of qualified fine powder is 35%. The powder has typical rapid solidification structure. Collision between powders not only promotes nucleation, but also produces more satellite powder. The segregation of elements in powder is smaller as the result of high cooling rate which can reaches 4.2 × 105 K/s in average. Overall, the powder prepared by gas atomization is found to have good comprehensive properties, desired microstructure, and accurate chemical component, and it is suitable for various additive manufacturing techniques.
25
Odunlade, T. V., A. A. Famuwagun, K. A. Taiwo, S. O. Gbadamosi, D. J. Oyedele y O. C. Adebooye. "Chemical Composition and Quality Characteristics of Wheat Bread Supplemented with Leafy Vegetable Powders". Journal of Food Quality 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/9536716.
Texto completoResumen
The study investigated the effect of supplementation of the leaf powders of Telfairia occidentalis, Amaranthus viridis, and Solanum macrocarpon on the chemical composition and the quality characteristics of wheat bread. The bread samples were supplemented with each of the vegetable leaf powders at 1%, 2%, and 3% during preparation. The bread samples were assayed for proximate composition, mineral composition, physical, sensory, and antioxidant properties using standard methods. The addition of vegetable powders significantly increased the protein (9.50 to 13.93%), fibre (1.81 to 4.00%), ash (1.05 to 2.38%), and fat (1.27 to 2.00%). Supplementation with vegetable powder however significantly decreased (p<0.05) the carbohydrate and moisture contents. Significant (p<0.05) increases were recorded for all evaluated minerals as the level of vegetable powder increased. Supplementation with vegetable powder caused significant decrease in total phenolic content, percentage DPPH inhibition, metal chelating ability, ferric reducing antioxidant power, and total antioxidant capacity. Sensory results showed that there was significant decrease in sensory qualities with increasing supplementation. This therefore suggests that bread supplemented with vegetable powder could have more market penetration if awareness is highly created.
26
Niwa, Koichi, Toshiaki Tanaka y Yasuro Ikuma. "Process Study of Nanosized Powder Dispersion for DEFC". Key Engineering Materials 617 (junio de 2014): 85–88. http://dx.doi.org/10.4028/www.scientific.net/kem.617.85.
Texto completoResumen
The process of obtaining a uniform dispersion of nanosized powders by applying two step process of mixing and adjusting viscosity was studied. The mixed paste was used as the electrode of direct ethanol fuel cells (DEFC). And power density of the fuel cells was measured. A high power density was realized by addition of acetone and propanol solvents to nanosized silica powder. However acetaldehyde concentration during the operation of these fuel cells did not decrease. An excess methanol was added to membrane electrode assembly composition of DEFC. The power density and current of DEFC were improved by adding methanol solvent. However, methanol addition over 55 % did not improve dispersion of nanosized powders. Transmission electron microscopy observation suggests that over 55% of methanol addition does not give good dispersion of nanosized powders.
27
Du, Bin, Shi Sheng Zhou y Nan Wang. "Influences of Surfactants on Gloss of Aluminum Paste Printing Ink". Advanced Materials Research 181-182 (enero de 2011): 679–84. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.679.
Texto completoResumen
In reflection to the fact that aluminum paste printing ink has lower gloss and poor masking power in China, it can not meet the requirements of printing production. In this paper, through the surface modification of coated aluminum powder, five kinds of single surfactant were coated on the surface of aluminum powder by wet method in different proportions. The wettability, the floating property and the gloss of the coated aluminum powder were measured, and the influence mechanisms of the surfactants on the wettability and floating property of the aluminum powders and gloss of the aluminum paste printing ink were analyzed as well. The results showed that the wettability of the aluminum powder coated by 1% Oleic acid has the largest decrease, the floating property of the aluminum powder coated by 3% Tween-80 has the largest increase and the aluminum powder coated by 1% Polyvinyl alcohol has the highest gloss. The gloss of the coated aluminum powder increases to 73.8. Modified aluminum paste printing ink has higher gloss and stronger masking, thus can meet the printing requirements for aluminum paste printing ink.
28
Hirata, Yoshihiro, Ichiroh Haraguchi y Yoshimi Ishihara. "Particle size effects on colloidal processing of oxide powders". Journal of Materials Research 7, n.º 9 (septiembre de 1992): 2572–78. http://dx.doi.org/10.1557/jmr.1992.2572.
Texto completoResumen
Rheological behavior, properties of colloidal solids consolidated by filtration, and their structure change during drying were studied with aqueous suspensions of a mullite powder of nanometer size and two kinds of alumina powders of submicrometer sizes. The rheological properties of non-Newtonian flow suspensions were analyzed by a power law equation of S = K γn, where S is the shear stress, γ the shear rate, and K and n (O ⋚ n ⋚ 1) constants. The critical solids content (Vc) at n = O (indicating colloidal solids) depended greatly on the zeta potential of particles in suspensions, and dominated the densities of dried green compacts (Vg) of submicrometer sized powders. In a nanometer sized powder, the densities of dried green compacts were dependent on both Vc value and the solid contents of suspensions. Phase diagrams of one-component colloidal systems were constructed by plotting the Vc and Vg values against the zeta potential of particles. These phase diagrams indicate that the colloidal solids range (surrounded by Vc and a minimum Vg lines) is narrow for nanometer sized powder and wide for submicrometer sized powder. The solids content range of dried green compacts was very narrow for submicrometer sized powder but relatively wide for nanometer sized powder due to the low flexibility of colloidal structure during drying.
29
Singh, Samridhi y Sunita Mishra. "Organoleptic and Morphological Analysis of Citrus Peel Powder". European Journal of Food Science and Technology 10, n.º 3 (15 de marzo de 2022): 24–38. http://dx.doi.org/10.37745/ejfst.2013/vol10n32438.
Texto completoResumen
Processing of citrus fruits results in production of a large amount of by product and a major part of this by product is its peels. These peels have the potential of acting as a good nutraceutical resource owing to its high dietary fibre content and phenolic content. However, these peels are under-utilised despite their claimed health benefits. This study evaluates the morphological structure, functional properties and sensory attributes of sweet lime peel and orange peel powder with a aim of providing an economical ingredient for the development of functional foods. Peels of sweet lime and orange were transformed into powder through solar drying followed by grinding. In the present study, we have compared the morphology and organoleptic constituents of orange peel powder (OPP) and sweet lime peel powder (SLPP). The morphology of the two samples was studied by SEM and element composition was studied and analysed by EDX. Organoleptic and sensory attributes were analyzed by a 9 pointer hedonic scale rating. Peel powders were also compared for two functional properties i.e. their Solubility Index and Swelling Power. Orange peel powder (OPP) had a better sensory rating than Sweet lime peel powder (SLPP). The morphology of both powders was same but SLPP had a slightly rough texture than OPP.
30
Yan, Lei, Xueyang Chen, Wei Li, Joseph Newkirk y Frank Liou. "Direct laser deposition of Ti-6Al-4V from elemental powder blends". Rapid Prototyping Journal 22, n.º 5 (15 de agosto de 2016): 810–16. http://dx.doi.org/10.1108/rpj-10-2015-0140.
Texto completoResumen
Purpose This paper aims to achieve Ti-6Al-4V from Ti, Al and V elemental powder blends using direct laser deposition (DLD) and to understand the effects of laser transverse speed and laser power on the initial fabrication of deposit’s microstructure and Vickers hardness. Design/methodology/approach Two sets of powder blends with different weight percentage ratio for three elemental powder were used during DLD process. Five experiments with different processing parameters were performed to evaluate how microstructure and Vickers hardness change with laser power and laser transverse speed. Energy dispersive X-ray spectroscopy, optical microscopy and Vickers hardness test were used to analyze deposits’ properties. Findings This paper reveals that significant variance of elemental powder’s size and density would cause lack of weight percentage of certain elements in final part and using multiple coaxial powder nozzles design would be a solution. Also, higher laser power or slower laser transverse speed tend to benefit the formation of finer microstructures and increase Vickers hardness. Originality/value This paper demonstrates a new method to fabricate Ti-6Al-4V and gives out a possible weight percentage ratio 87:7:6 for Ti:Al:V at powder blends during DLD process. The relationship between microstructure and Vickers hardness with laser power and laser transverse speed would provide valuable reference for people working on tailoring material properties using elemental powder method.
31
Condruz, Mihaela Raluca, Gheorghe Matache y Alexandru Paraschiv. "Characterization of IN 625 recycled metal powder used for selective laser melting". Manufacturing Review 7 (2020): 5. http://dx.doi.org/10.1051/mfreview/2020002.
Texto completoResumen
Additive manufacturing of high-quality materials by Selective Laser Melting depends not only on establishing appropriate process parameters, but also on the characteristics of the metal powders used and their stability over time or after recycling. The aim of the research was to characterize the IN 625 powder used over multiple manufacturing cycles with a Lasertec 30 SLM machine. In order to achieve the research's goal, virgin and recirculated powder's physical and technological characteristics were investigated. A decrease in all D-values (D10, D50, D90) of the powder size distribution was observed after multiple recirculation cycles showing a decrease of the powder dimensional range over time. Both virgin and recirculated powders are composed of mainly spherical particles, but elongated particles and satellite particles were observed as well. The dimensional evolution analysis showed a deviation from the powder ideal roundness, deviation that is more pronounced over multiple recirculation cycles. It was experimentally determined that the powders present a good flowability based on the flow rate value obtained for both virgin and recirculated powders, confirmed also by the Hausner ratio and angle of repose.
32
Muhamad, Norhamidi, Javad Rajabi, Abu Bakar Sulong, Abdolali Fayyaz y Muhammad Rafi Raza. "Micro Powder Injection Moulding Using Nanosized Powders". Advanced Materials Research 1024 (agosto de 2014): 116–19. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.116.
Texto completoResumen
Micro powder injection moulding (μPIM) is one of the micro-moulding technology applied today in high-volume fabrication of metal and ceramic micro-components. The current study presents the micro powder injection moulding (µPIM) of 316L Stainless Steel nanopowder-polymer mixtures. 316L SS powders have been blended with a binder system which consists of Polyethylene Glycol (PEG), Polymethyl Methacrylate (PMMA) and Stearic Acid (SA). All the feedstock prepared shows homogeneity and pseudo-plastic behaviour which is suitable for μPIM process. The results showed that increase in nano powder content would improve the powder loading, injection and sintering temperature. Moreover, high physical and mechanical properties of the sintered specimen have been achieved under vacuum atmosphere. The above results indicate that application of nano powder has the potential to provide micro powder injection moulded parts with nearly full density, fine microstructure. The binder system is environment-friendly, has low viscosity-temperature and suitable to prepare feedstock for μPIM.
33
Wang, Ru Wu, Feng Quan Zhang, Ding Wei, Ze Min Fang, Chun Zeng y Zhong Han Luo. "Influence of Compaction Pressure on Magnetic Properties of Sendust Powder Core". Materials Science Forum 852 (abril de 2016): 79–83. http://dx.doi.org/10.4028/www.scientific.net/msf.852.79.
Texto completoResumen
Toroid-shaped soft magnetic powder cores (SMCs) were produced by cold pressing of the commercial sendust alloy powders. The characteristics of the commercial sendust alloy powder and the effect of compaction pressure on the magnetic properties, i.e., effective permeability μe, quality factor Q, DC-bias properties and volume power loss of sendust alloy powder cores were investigated. The results showed that the sendust alloy powder core with shaping pressure of 1932 MPa, annealing temperature of 953 K for 1 h and dielectric content of 0.96% presents the optimum magnetic properties with an effective permeability of 90, a total loss of 386 mW/cm3 at f=50 kHz and Bm=0.1 T, a DC-bias property of 64% at H=50 Oe.
34
Zhang, Lan Chun, Shao Yi Bei y Guo Qing Li. "Study on Dynamic Shifting of Power Split CVT (PSCVT)". Advanced Materials Research 580 (octubre de 2012): 28–32. http://dx.doi.org/10.4028/www.scientific.net/amr.580.28.
Texto completoResumen
In order to study the shift control of power split continuously variable transmission (PSCVT), the integrated shift dynamic models for the set of engine, magnetic powder clutch and transmission are established. The shift simulation shows that the magnetic powder clutch connecting condition can be adjusted and the shifting quality can be improved by means of controlling magnetic powders clutch field current, which at last result in the improvement of vehicle performance.
35
Pham, D. T., K. D. Dotchev y W. A. Y. Yusoff. "Deterioration of polyamide powder properties in the laser sintering process". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, n.º 11 (1 de noviembre de 2008): 2163–76. http://dx.doi.org/10.1243/09544062jmes839.
Texto completoResumen
Polyamide 12 (PA12)-based powders are the most used materials in the laser sintering (LS) process for rapid manufacturing of functional parts. An average of 80–90 per cent of the powdered material in the LS building chamber is not sintered and could be reused. However, the properties of the recycled powder vary, which ultimately affects the quality of produced parts. These differences are due to the process conditions such as temperature and time, the LS machine design, and properties of the powder used for parts fabrication. This paper analyses the LS processing conditions and current recycling practices in relation with the deterioration or ageing of the PA12-based powders. Samples of new and recycled grades of PA2200 powder were artificially aged in a temperature-controlled oven and then tested using differential scanning calorimetry, melt flowrate indexer, and gel permeation chromatography. It has been found that the temperature and the time at which the unsintered powder was exposed are the most influential factors for the deterioration of LS powder properties.
36
Min, Tao, Sun Yan-Hui, Tao Yu-Gui, Miao Wen-juan y Ge Fei. "Comparison of Physicochemical Characteristics of Submicron Powder and Common Powder of Chrysanthemum morifolium Chuju". Current Topics in Nutraceutical Research 17, n.º 2 (8 de mayo de 2018): 172–79. http://dx.doi.org/10.37290/ctnr2641-452x.17:172-179.
Texto completoResumen
The physicochemical characteristics of Chrysanthemum morifolium Chuju powders were investigated to increase its utilization value and to develop novel products. Comparing the physicochemical properties between the submicron powder and common powder, the indicators of repose angle, slip angle, solubility, soakage, dispersibility, the images of SEM, and dissolution of main active components were obtained to evaluate the quality of powder products. The repose angle of submicron powder was 36.76º, while that of the common powder was 48.77º, which represents the appreciable flowability of submicron powder. The wetting time of submicron powder was 103s, which was way less than that of common powder (8963s). The SEM micrographs showed that submicron powder had long cracks on its plant cell. The HPLC chromatograms indicated that the dissolution of submicron powder was higher than that of common powder. The results showed that not only physical but also chemical characteristics of submicron powders were much superior than those of common powders.
37
Sato, Naoko, Masaki Ito, Takayuki Izumida, Toru Shimizu y Shizuka Nakano. "Usability of Ti6Al4V Powder via Hydride-Dehydride Process for Selective Laser Melting Process". Materials Science Forum 879 (noviembre de 2016): 1698–702. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1698.
Texto completoResumen
Spherical powders via gas atomization etc. are recommended for use in SLM, however, the spherical powders are expensive and able to make in limited types of metal materials. Using non-spherical powder in SLM are capable of applying SLM to cheap part production and diversify powder materials for SLM. In this paper, to study the feasibility of using Ti6Al4V milled powder via hydride-dehydride method for SLM, characteristics of powders, powder bed performances, and SLM fabricated samples made from gas atomization powder and milled powder were analyzed and compared. The milled powder which added a fumed silica as a lubricant were also analyzed. In the results, flow and packing characteristics of the milled powder are lower than the gas atomized one. The characteristics of the milled powder are improved by adding fumed silica as lubricant, and had comparable characteristics to the gas atomized one. Microstructure of the SLM fabricated samples has a comparable size and morphology regardless of powders. Hardness of the SLM fabricated sample made from milled powder are larger than that of it made from gas atomized powder, owing to solid solution hardening by oxygen.
38
Hupalo, Marcio Ferreira, Selauco Vurobi Jr., Ricardo Sanson Namur, Isabela Rodrigues Diniz y Osvaldo Mitsuyuki Cintho. "Sintering of AISI M2 Tool Steel Processed in High-Energy Planetary Mill". Materials Science Forum 899 (julio de 2017): 505–10. http://dx.doi.org/10.4028/www.scientific.net/msf.899.505.
Texto completoResumen
This work aimed to evaluate the effect of pre-sintering annealing heat treatments and sintering times in AISI M2 high-speed steel powders processed by high energy milling. Turning chips were obtained from an AISI M2 drill bit that was annealed during 2 hours at 900°C, under argon atmosphere, before machining. Subsequently, the chips were milled during 10 hours in a high energy planetary mill with a power ratio of 10:1, also under argon atmosphere. Half of the powder mass was annealed at 650oC during 30 minutes under argon atmosphere after milling. Three different samples were prepared, consisting of: non-annealed powder, annealed powder and a mixture 1:1 of annealed and non-annealed powders. All powders were compacted by uniaxial pressing before sintered. Compressibility curves were obtained for all samples. Sintering process was conducted at 1200°C during 1, 2 and 3 hours and samples were cooled inside the furnace. The annealed powder sample presented the best compactation behavior, due to its restored ductility, followed by the 1:1 mixture of annealed and non-annealed powders. The microstructure of sintered samples displayed a ferritic matrix surrounded by carbide networks at grain boundaries. Higher sintering times resulted in carbon impoverishing, leading to lower volume fractions of carbides and hence reducing its hardness. Non-annealed powders showed higher dependency of sintering time to reduce their porosity. The best results were obtained for the annealed powder with shorter sintering time, since it presented low volume fraction of porosities and smaller grain sizes.
39
H. Abbar, Ali, Jameel Y. Abdul-Ridha y Sameer H. Kareem. "Electrolytic preparation of Iron powder with particle Size Less than 106 pm". Iraqi Journal of Chemical and Petroleum Engineering 8, n.º 1 (30 de marzo de 2007): 51–57. http://dx.doi.org/10.31699/ijcpe.2007.1.8.
Texto completoResumen
Avery large numbers of articles are made by powder metallurgical methods using electrolytically reduced metal powders. Iron powder is one of these powders which play an important role in this field. Its preparation by electrolytic method is economic in comparison with the traditional methods (Atomization and carbonyl processes).
An electrochemical cell consisting of two electrodes (stainless steel cathode and iron anode, 99.9%) was used to study the electrolytic preparation of iron powder with particle size less than 106µm directly as powde1y form. Ferrous sulphate electrolyte was used containing sodium chloride as a stabilizing agent. The produced powder was thoroughly washed with an acidified distilled water and absolute ethanol, then dried under an inert atmosphere at 80°C, and classified by screening. Samples of prepared powder were taken to determine their purity by atomic absorption. The effects of current density, metal ion concentration, sodium chloride concentration, PH, and electrolysis time on the weight percent of iron powder less than (106µm), yield and current efficiency were studied.
It was found that an iron powder with particle size less than 106µm can be prepared at a weight percent of iron powder less than I06µm (89.7%) and current efficiency of 71% using cathodic current density of 0.1 A/cm3 and electrolysis time equal to 1 hr. The prepared powder having an apparent density of (3.24 gm/cm3 and real density of 7.39 gm/cm3 with specific surface area of 238 X 103 cm2/gm. Its average particle size was 75 pm and its purity was 99.14%
40
Zeng, Wei Liang, Yan Ling Guo, Ying Liu, Yan Ping Gong, Pei Feng Zhao, Chi Lei Li y Jian Wei Zhao. "A New Rice Husk-Plastic Composite Powder Preparation Process for Selective Laser Sintering Fabrication". Advanced Materials Research 750-752 (agosto de 2013): 1577–81. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.1577.
Texto completoResumen
A new powder material, rice husk-plastic composite powder (RPC), was successfully developed for selective laser sintering (SLS) process. RPC is mainly composed of rice husk powder and a hot-melt adhesive powder, it is a green and biological material and its most important advantage is low-cost, but because the hull surface of rice is burr and not smooth, easily jammed between particles, poor mobility, is not the medium of easy flowing, so mixing process was successfully developed to prepare RPC powders. The preparation process is divided to three steps. First, before mix, the rice husk power is dried for reducing the hydrophilic nature of rice husk fiber and improving the wettability and the adhesion actions of the interface. Then, put the PES hot melt adhesive, the dried wood powder and the acetone solution which contain coupling agent and initiator together to mix evenly. At last, dry the basic material at the constant temperature of 45±2°C in the oven, add the organic filler and light stabilizer. Finally, RPC powder for SLS is got. As the result of SLS fabrication, part made by RPC powder is got, its mechanical properties and dimensional accuracy is satisfied.
41
Kaye, Brian H. y Munetake Satoh. "Powder Mixing (Powder Technology Series)". Advanced Powder Technology 10, n.º 3 (1999): 315. http://dx.doi.org/10.1163/156855299x00361.
Texto completo
42
Kirchner, Alexander, Burghardt Klöden, Marie Franke-Jurisch, Gunnar Walther y Thomas Weißgärber. "Electron Beam Powder Bed Fusion of Water Atomized Iron and Powder Blends". Materials 15, n.º 4 (19 de febrero de 2022): 1567. http://dx.doi.org/10.3390/ma15041567.
Texto completoResumen
In the present state of the art, highly spherical alloy powders are employed as feedstock in powder bed fusion processes. These powders are characterized by high flowability and apparent density. Their elaborate fabrication process is reflected in high powder price, adding a significant fraction to the cost of additively manufactured parts. Thus, the use of non-spherical powders, such as water atomized material, can lower costs significantly. Here, the electron beam powder bed fusion (PBF-EB) of standard water atomized iron powder used for press-and-sinter is studied. Despite raking problems, using the coating mechanism in standard configuration samples with densities exceeding 99% were fabricated. In a further step, the addition of alloying elements by powder blending is explored. Important powder properties of feedstock blended from irregular and spherical powders are characterized. The PBF-EB processing of two alloys is presented. The first represents a low carbon steel. Samples were characterized by metallographic cross-section, energy dispersive X-ray (EDX) mapping, and mechanical testing. The second alloy system is a FeCrAl. After PBF-EB processing of the powder mixture, chemical homogeneity was achieved. Besides the low cost, this approach of using water atomized powder mixed with master alloy offers the advantage of high flexibility for potential application.
43
Fedina, Tatiana, Jesper Sundqvist y Alexander F. H. Kaplan. "The use of non-spherical powder particles in Laser Powder Bed Fusion". IOP Conference Series: Materials Science and Engineering 1135, n.º 1 (1 de noviembre de 2021): 012018. http://dx.doi.org/10.1088/1757-899x/1135/1/012018.
Texto completoResumen
Abstract Laser powder bed fusion (LPBF) generally involves the use of near-spherical powders due to their smooth morphology and enhanced flowability that allow for easier powder layering and laser processing. Non-spherical powders, on the other hand, are more cost-efficient to manufacture, however, the underlying mechanisms of their movement and interparticle interaction on the powder bed are still unclear. Thus, this study reports on the use of irregular iron-based powder material in LPBF, with a specific focus on particle motion and interaction behavior on the powder bed. The powder morphology, sphericity and particle size were analysed using X-ray computed microtomography and scanning electron microscopy. Based on the acquired data and by using a simplified analytical calculation, the influence of the particle shape/size on the particle movement in LPBF was established. High-speed imaging was employed to investigate the particle flow dynamics in the process zone, as well as the powder entrainment phenomenon. Particle entrainment and entrainment distances along the scanning direction were measured for near-spherical and non-spherical powders. The obtained results were compared between the powders, revealing a dissimilar particle transfer behavior. Non-spherical powder had a shorter entrainment distance partly attributed to the weaker drag force acting on these particles.
44
Wu, Xinzhou, Hui Ren y Qingjie Jiao. "Improved Combustion Performance of Fluororubber-Coated Micro-Nano Composite Aluminum Powder". Metals 13, n.º 3 (10 de marzo de 2023): 556. http://dx.doi.org/10.3390/met13030556.
Texto completoResumen
In order to improve the reaction rate and reaction degree of aluminized explosives, the micro-nano composite aluminum powder was fabricated by a new method of in situ electro-explosion. The combustion performances of the composite aluminum powder were studied. The results showed that the micro-nano composite aluminum powder was like a “sea urchin structure” with many nano-sized powders around a single micro-sized aluminum particle. The heat of combustion was 25.67 MJ/kg at 3 MPa oxygen pressure, and the rising rate of pressure was particularly obvious. The ignition performance in an air environment was much better than the micro-sized aluminum powder. At the same time, the reaction process of the micro-nano composite aluminum powder was analyzed. The reaction can be divided into three stages, the decomposition of fluororubber between 500 and 600 °C, then melting, and the first step of the oxidation of aluminum powder occurred between 600 and 700 °C. In the third stage, the micro-nano composite aluminum powder reacted violently around 1000 °C and the released energy reached 3779 J/g. The micro-nano composite aluminum powder had excellent combustion performance and a good application prospect in high-power energy storage materials.
45
Guo, Yan Ling, Yue Qiang Yu y Kai Yi Jiang. "Study on the Forming Accuracy and Density of Eucalyptus/PES Fabricated by Laser Sintering". Key Engineering Materials 667 (octubre de 2015): 200–205. http://dx.doi.org/10.4028/www.scientific.net/kem.667.200.
Texto completoResumen
. Based on orthogonal test, the forming accuracy and density of laser sintering eucalyptus/PES blend is studied in this paper. It mainly analysed the effect of the powder size and process parameters (such as laser power, layer thickness, preheating temperature, etc) on the forming precision and density of sintered eucalyptus/PES parts, also the correlation analysis of molding error caused by the powder’s physical properties and machine is performed. By measuring the parts’ dimensions, the results show that the laser power and powder size are two main factors influencing parts’ density, and variable density, layer thickness and preheating temperature jointly affect the dimensional accuracy. The optimized processing parameters are obtained. The powder size, laser power, scanning rate, layers thickness and preheating temperature are 300 mesh, 43W, 2000mm/s, 0.1mm, 60°C respectively.
46
Sharma, Rahul, Ramesh Chandra Agarwala y Vijaya Agarwala. "Development of Electroless Ni-P/NRAM Nanocomposite Powder with Enhanced Microwave Absorption Properties". Advanced Materials Research 67 (abril de 2009): 59–64. http://dx.doi.org/10.4028/www.scientific.net/amr.67.59.
Texto completoResumen
Nano radar absorbing material (NRAM) i.e. BaMe2Fe16O27 (Me2+=Fe2+) powder (10 nm) is coated with amorphous Ni-P nano layer (5-10 nm) by using electroless (EL) technology to develop EL Ni-P/NRAM nanocomposite powder. The experimental processes parameters and EL Ni-P bath composition were optimized to obtain the deposition. As-deposited nanocomposite powder was microwave annealed (MWA) with increasing radiation power from 160 to 760 watts for 5 minutes. The surface morphology, elemental contents, phase transformation and magnetic properties of NRAM powders were examined under field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) respectively. Maximum reflection loss (RL) 33.75 dB at 15.80 GHz for nanocomposite powder MWA at 760 watt was obtained the absorption range under −15 dB is from 13.76 to 16.77 GHz with 2 mm thickness layer in Ku Band. Excellent microwave absorption properties due to accurate electromagnetic (EM) match in the nanocomposite microstructure, a strong natural resonance and multipolarization. Such (Ni+ Ni3P)/NRAM nanocomposite powders may be attractive candidates for EM absorption.
47
Itoh, Takashi y Akira Tominaga. "Thermoelectric Properties of Al-doped Mg2Si Compounds Prepared via Three Kinds of Process for Grain Refinement". MRS Advances 1, n.º 60 (2016): 3989–95. http://dx.doi.org/10.1557/adv.2016.374.
Texto completoResumen
ABSTRACTDimagnesium silicide is an eco-friendly thermoelectric compound whose constituent elements of both Mg and Si are non-toxic and exist in abundance on the earth. In this study, we attempted to control the thermal conductivity of Al-doped Mg2Si by grain refinement. Three types of Si powders, i.e., commercial coarse powder, its pulverized powder and commercial fine powder were prepared for synthesizing the Al-doped Mg2Si. Mg powder and one of the Si powders were weighed with Mg/Si mole ratio of 67/33, and mixed with Al powder with amount of 0.1 at.%. The Al-doped Mg2Si compounds were synthesized using three different Si powders via a liquid-solid phase reaction process under unified synthesizing conditions. A part of the synthesized Mg2Si powder using the coarse Si powder was pulverized. Four kinds of Mg2Si powders were sintered by pulse discharge sintering method under unified sintering conditions. The sintered samples of the synthesized Mg2Si powders made from the fine and the milled Si powders and of the milled Mg2Si powder had the grain-refined microstructure. Especially, the sintered sample of the milled Mg2Si powder was effective for grain refinement and for reduction of thermal conductivity, and had the best thermoelectric performance of ZT = 1.15 at 873 K.
48
Chikosha, Silethelwe, Linda M. Mahlatji y Hilda K. Chikwanda. "Characterisation of Titanium Powder Flow, Shear and Bulk Properties Using the FT4 Powder Rheometer". Advanced Materials Research 1019 (octubre de 2014): 218–24. http://dx.doi.org/10.4028/www.scientific.net/amr.1019.218.
Texto completoResumen
In order to reliably design and operate different powder processes, an understanding of the dynamic flow, shear and bulk properties of powders is required. Generally, powders are evaluated by several techniques that determine their flow, shear and bulk properties. The techniques can include compression tests, shear tests, angle of repose, flow of powder in a funnel, tapped density and many others. In order to minimize the number of instruments required to characterise the powder and eliminate operator error, automated powder rheometers that can do most of the required tests have been developed. The FT4 powder rheometer is one of these and has found widespread use in the pharmaceutical industry. In this study, the FT4 powder rheometer was used to characterise two metallic titanium powders with different particle sizes, namely CSIR Ti-45μm (Fine Powder) and CSIR Ti +45-180μm (Coarse Powder). Their particle size, particle size distribution, bulk densities, compressibility, cohesion, flowability index, effective angle of internal friction and wall friction angle were determined. Preliminary results of the study indicated that fine powder had a lower bulk density, was more compressible and more cohesive than the coarse powder. The fine powder had a lower flowability index compared to the coarse powder for both the Jenike and Peschl classification. The varying degrees of cohesion of these powders were confirmed by the cohesion values that were higher for the fine powder. The fine powder had a lower angle of internal friction but higher wall friction angle compared to the coarse powder.
49
Fan, Xiaobao, Takamasa Ishigaki y Yoichiro Sato. "Phase formation in molybdenum disilicide powders during in-flight induction plasma treatment". Journal of Materials Research 12, n.º 5 (mayo de 1997): 1315–26. http://dx.doi.org/10.1557/jmr.1997.0180.
Texto completoResumen
In-flight modification of MoSi2 powders has been carried out by using an Ar–H2 induction plasma. Reactor pressure, powder feed rate, and plate power level were taken as the experimental parameters to alter the thermal history of the injected powder particles. Metastable hexagonal structure of β–MoSi2 is the major phase observed in the Ar–H2 induction plasma-treated molybdenum disilicide powders, while the stable phase of tetragonal structure of α–MoSi2 usually retains no less than 30 wt. %. Depending on the experimental condition and the deviation from stoichiometry in raw materials, low silicides, Mo5Si3 and Mo3Si, and free Si were observed,
50
Masalimov, Dinar R., Roman R. Galiullin, Rinat N. Sayfullin, Azamat F. Fayurshin y Linar F. Islamov. "Investigation of pre-sprayed powders for electric contact welding". Tekhnicheskiy servis mashin, n.º 1 (1 de marzo de 2020): 143–49. http://dx.doi.org/10.22314/2618-8287-2020-58-1-143-149.
Texto completoResumen
There are a number of difficulties in the electrical contact welding of powder materials: shedding of powder from the surface of a cylindrical part, impossibility of hardening the layer during welding due to flushing of the powders with coolant and unstable flow of powder into the welding zone. One solution is pre-spraying the powder in some way. (Research purpose). The research purpose is investigating the possibility of electric contact welding of metal powders preliminarily sprayed by a gas-flame method, namely, adhesion strength and losses during preliminary gas-flame spraying of powders. (Materials and methods) Powders of grades PG-NA-01, PrKhIIG4SR, PRZh3.200.28 were sprayed onto flat samples of St3 steel, polished to a roughness of Ra 1.25. The strength of powder adhesion to the base was studied by the cut method. (Results and discussion) The percentage loss of the powder as a whole is 3-23 percent for all the distances studied. The greatest powder losses appear at a distance of more than 180 millimeter from the tip of the burner for powders of grades PG-NA-01 and PrKhIIG4SR. The smallest powder losses were observed for PrZh3.200.28 powder, which totaled 3-7 percent. The maximum adhesion strength of the sprayed powders to the surface was 22.1 megapascals' when spraying the PG-NA-01 powder. The adhesion strength of powders of the grades PrKhIIG4SR and PrZh3.200.28 is small and amounts to 0.2-3 megapascals'. (Conclusions) The use of preliminary flame spraying of powders for their further electric contact welding is possible using PG-NA-01 grade powder, while the best adhesion to the base (that is more than 20 megapascals') is achieved with a spraying distance of 120-140 millimeter. The smallest powder losses during flame spraying are achieved at a spraying distance of 100-160 centimeters', at which the powder loss for the studied grades was 4-12 percent.