scholarly journals Influence of gas atomization parameters of alloy KhN60M on the characteristics of powder for laser surfacing

2019 ◽  
pp. 14-21
Author(s):  
K. V. Kalinin ◽  
S. A. Oglezneva ◽  
M. S. Nagaev
Keyword(s):  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Size Composition ◽  
Additive Technologies ◽  
Spherical Particles ◽  
Average Particle ◽  
Gas Atomization ◽  
Laser Surfacing ◽  
Heat Resistant Alloy ◽  
Advantages And Disadvantages

The object of the study was alloy powders KhN60М (EP367; 06Kh15N60М1). An overview of methods for manufacturing products from heat-resistant alloy KhN60M with an analysis of their advantages and disadvantages is given. It is shown that in comparison with injection molding and hot pressing of powders from high-alloyed special steels and alloys, additive technologies allow to obtain products of complex shape with a high level of physical and mechanical properties and material utilization. The low casting properties of the alloy under study cause the research of the atomization to meet the requirements for size, shape, morphology and fluidity of powders for additive technologies. The goal of the work was to study the effect of argon pressure during gas atomization on the physical, chemical, technological properties of powders for laser surfacing, obtained from alloy KhN60М. The technology of gas spraying of liquid melt with argon on a VIGA 2B laboratory atomizer at a temperature of 1560 °C and varying the pressure of the spraying gas in the range of 22–25 mbar was used for the manufacture of metal powder KhN60М. To select the atomization parameters, the melt viscosity values were calculated using the finite element method and its temperature dependence was constructed. The calculations were made with the ProCAST computer modeling system for casting processes. The shape and size of particles, the grain size composition were investigated using laser sedimentation, electron and optical microscopy. Quantitative metallography data were processed using the VideoTest 4 software. Fluidity of powders was measured. It was found that with increasing pressure of the spraying gas, the proportion of spherical particles increased and the fluidity of the powders improved; Feret diameter, average particle size, and d50 values did not change significantly. An experimental dependence of the increase in the yield of the powder of the target fraction (40–80 μm) with a decrease in the volume of the spray gas supply was obtained. An inversely proportional dependence of the fraction of spherical particles on the fraction of the desired cut was established. The results of the study make it possible to predict the values of the output parameters of powders during the atomization of steel KhN60M. Characteristics of powders of the –80+40 μm fraction with a shape factor of 0.99 and a yield point of 14–15 g/s make it possible to use them for the manufacture of products using additive technologies.

Experimental Study on the Effects of Internal Erosion on the Physical and Mechanical Properties of Tailings Under Unsteady Seepage

2021 ◽  
Author(s):  
Rong Gui ◽  
Guicheng He
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Shear Strength ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Internal Erosion ◽  
Average Particle ◽  
Sand Column ◽  
Sedimentary Characteristics ◽  
Seepage Erosion

Abstract In this paper, the hydraulic sedimentary model was established to investigate the effects of dry beach slope on the sedimentary characteristics of tailings, and the sand column model was built to investigate the effects of seepage erosion on the physical and mechanical properties of sedimentary tailings under unsteady seepage.The results show that the slope of dry beach have a great effect on the sedimentary characteristics of tailings, the average particle size of tailings decreases along the slope of dry beach, and the larger the slope, the more obvious the stratification of the tailings. The migration of fine-grained tailings caused by seepage erosion increases the permeability of the tailings and reduces the shear strength of the tailings. After seepage erosion,the average particle size of 1#tailings sample, 2#tailings sample and 3#tailings sample increased by 6.4%, 12.0% and 2.4% respectively, the hydraulic conductivity of 1# tailings sample, 2# tailings sample and 3# tailings increased by 27.2%,17.9%, and 15.3% respectively after internal erosion, and the shear strength of 1#tailings sample, 2#tailings sample and 3#tailings sample tailings sample decreased by 20.9 %, 15.1% and 12.4% respectively.

scholarly journals Preparation, Characterization, and In Vivo Pharmacokinetic Study of the Supercritical Fluid-Processed Liposomal Amphotericin B

Pharmaceutics ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 589 ◽  
Author(s):  
Chang-baek Lim ◽  
Sharif Md Abuzar ◽  
Pankaj Ranjan Karn ◽  
Wonkyung Cho ◽  
Hee Jun Park ◽  
...  
Keyword(s):  
Particle Size ◽  
Amphotericin B ◽  
Supercritical Fluid ◽  
Liposomal Amphotericin ◽  
Average Particle Size ◽  
Spherical Particles ◽  
Liposomal Amphotericin B ◽  
Average Particle ◽  
In Vivo Pharmacokinetics

Here, we aimed to prepare and optimize liposomal amphotericin B (AmB) while using the supercritical fluid of carbon dioxide (SCF-CO2) method and investigate the characteristics and pharmacokinetics of the SCF-CO2-processed liposomal AmB. Liposomes containing phospholipids, ascorbic acid (vit C), and cholesterol were prepared by the SCF-CO2 method at an optimized pressure and temperature; conventional liposomes were also prepared using the thin film hydration method and then compared with the SCF-CO2-processed-liposomes. The optimized formulation was evaluated by in vitro hemolysis tests on rat erythrocytes and in vivo pharmacokinetics after intravenous administration to Sprague-Dawley rats and compared with a marketed AmB micellar formulation, Fungizone®, and a liposomal formulation, AmBisome®. The results of the characterization studies demonstrated that the SCF-CO2-processed-liposomes were spherical particles with an average particle size of 137 nm (after homogenization) and drug encapsulation efficiency (EE) was about 90%. After freeze-drying, mean particle size, EE, and zeta potential were not significantly changed. The stability study of the liposomes showed that liposomal AmB that was prepared by the SCF method was stable over time. In vivo pharmacokinetics revealed that the SCF-CO2-processed-liposomes were bioequivalent to AmBisome®; the hemolytic test depicted less hematotoxicity than Fungizone®. Therefore, this method could serve as a potential alternative for preparing liposomal AmB for industrial applications.

Effect of Surfactant on the Preparation of Nano-powder for Yb Doping Laser Transparent YAG Ceramic

2013 ◽  
Vol 32 (5) ◽  
pp. 511-515 ◽  
Author(s):  
Xiao Guo Cao ◽  
Jia Wang ◽  
Qi Bai Wu ◽  
Hai Yan Zhang
Keyword(s):  
Particle Size ◽  
Polyethylene Glycol ◽  
Average Particle Size ◽  
Ammonium Bicarbonate ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Nano Powder ◽  
Co Precipitation

AbstractYb:YAG transparent ceramic nano-powder was prepared by chemical co-precipitation method, with ammonium bicarbonate as the precipitant and polyethylene glycol as surfactant. The addition of polyethylene glycol can reduce the agglomeration and particle size of the prepared Yb:YAG powder. The morphology, thermal stability and phase structure of Yb:YAG nano-powder were charactered by scanning electron microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. The results show that well-crystallized nano-powder was obtained by calcining the precursors at 900 °C for 3 h. The average particle size of Yb:YAG powder is about 100–200 nm. When the volume amount of polyethylene glycol is 2.0%, well-dispersed Yb:YAG powder with spherical particles of 100 nm diameter was obtained.

scholarly journals Application of surfactants for the synthesis of qualitative hydroxide and metallic cobalt nanopowders

2021 ◽  
pp. 4-11
Author(s):  
Van Minh Nguyen ◽  
Tien Hiep Nguyen ◽  
Stanislav V. Gorobinsky
Keyword(s):  
Particle Size ◽  
Hydrogen Reduction ◽  
Cetylpyridinium Chloride ◽  
Average Particle Size ◽  
Sodium Dodecyl ◽  
Chemical Precipitation ◽  
Spherical Particles ◽  
Narrow Particle Size Distribution ◽  
Average Particle ◽  
Application Of Surfactants

In this work, nanopowders (NP) Co(OH)2 were obtained by chemical precipitation from aqueous solutions of cobalt nitrate Co(NO3)2 and alkali NaOH (10 wt. %) using surfactants: sodium dodecyl sulfate (SDS) and cetylpyridinium chloride (CPC) (0.1 wt. %). It was shown that Co(OH)2 NP with 0.1% SDS is the best quality product, since its dispersion increases more than 2 times compared to the samples with 0.1% CPC and without surfactants. In this case, the Co(OH)2 NP has the form of flakes with an irregular shape and a nanometer size (about 100 nm) with an average thickness of 30 nm. It was found that the average particle size of Co NP obtained by hydrogen reduction of Co(OH)2 NP with 0.1% SDS at 280°C has a maximum on the distribution histogram shifted to the interval 41–50 nm, which is characterized by a narrow particle size distribution and represents spherical particles sintered with each other.

scholarly journals Production and Characterization of Commercial Aluminum Powders by a New Nozzle Design and Atomization Unit

2021 ◽  
Vol 9 (12) ◽  
pp. 1259-1263
Author(s):  
Hakan Gokmese
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Experimental Studies ◽  
Average Particle ◽  
Powder Size ◽  
Gas Atomization ◽  
Pure Aluminium ◽  
Metal Powders ◽  
Important Place ◽  
Measuring Device

Abstract: A large area cross section of the production of spherical metal powders by gas atomization in the manufacturing method. Powder metal characteristic improves with small powder size. This aim was realized by vertical gas atomization unit, a new a closely-matched nozzle system and manufacture. In the experimental studies, pure aluminium powders which has an important place in the automotive, air and defence industries were produced. In the studies carried out with the Vertical Gas Atomization unit, aluminium was superheated up to 900°C and atomized at different gas pressures (20-30 bar). Scanning electron microscope (SEM) and particle size measuring device were used for the characterization and size measurements of the produced powders, respectively. The average particle size of the finest powder produced with increasing atomization pressure was determined as d50=19.50µm. Aluminium powder shape and morphology was used as spherical and very little satellization was seen. Keywords: Powder Metallurgy, Atomisation, Nozzle, Al powder, Characterisation

Microwave Assisted Green Synthesis of Silver Nanoparticles Using Mulberry Leaves Extract and Silver Nitrate Solution

2018 ◽  
Author(s):  
Liem Le ◽  
The Nguyen ◽  
Dieu Nguyen
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Nitrate Solution ◽  
Average Particle Size ◽  
Silver Nitrate Solution ◽  
Spherical Particles ◽  
Average Particle ◽  
Mulberry Leaves ◽  
Microwave Assisted ◽  
Microwave Assisted Method

In this work, silver nanoparticles (AgNPs) were synthesized rapidly and eco-friendlily using the extract of Mulberry leaves and aqueous solution of silver nitrate without any toxic chemical [1,2]. The Mulberry leaves extract acts as both reducing agent and stabilizing agent. The UV-Vis spectrum shows peak at 430 nm. The TEM image of synthesized AgNPs sample shows spherical shaped particles whose size range from 15 to 20 nm. TEM image of nano silver solution sample synthesized by microwave assisted method shows nearly spherical particles with an average particle size of 10 nm. The absorption UV-vis spectrum of silver nanoparticles synthesized by microwave assisted method (AgNPsmw) shows a sharp absorption band around 415 nm. After two month storage of AgNPsmw, the absorption spectrum of AgNPsmw was taken again. The UV-Vis spectrum shows negligible peak changes of silver nanoparticles have occurred after two months of storage. The synthesized AgNPs material could be used as an antimicrobial, used in the field of textile and in wastewater treatment.

Preparation and Friction Performance of the Nano Ag-APS Single Molecular Self-Assembled Film

2013 ◽  
Vol 800 ◽  
pp. 351-355
Author(s):  
Jun Hong Guo ◽  
Jin Feng Cui ◽  
Shu Hui Li ◽  
Xue Mei Bao ◽  
Xiang Ming Yao ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Chemical Structure ◽  
Sodium Citrate ◽  
Average Particle Size ◽  
Spherical Particles ◽  
Average Particle ◽  
Ag Nanoparticle ◽  
Structure And Morphology ◽  
Self Assembled ◽  
Friction Performance

The Ag nanoparticles was prepared by reduction of silver nitrate with sodium citrate, and the APS monolayers was self-assembled with 3-Aminopropyltrimethoxysilane (APS) on the monocrystalline silicon surface. Then, Ag/APS molecular self-assembled film was formed with Ag nanoparticles and APS membrane by liquid method. The chemical structure and morphology of the Ag nanoparticles and self-assembled film were investigated by AFM, XRS and IR. Meanwhile, the friction performances of self-assembled film was also investigated. The results shown that the Ag nanoparticle have the morphology of spherical particles with an average particle size of ca. 65 nm in diameter which were successful assembled on the surface of APS film and partially oxidized into Ag2O. The friction coefficient of the Ag-APS molecular self-assembled film has been decreased with the assembled time extened while the wear rate has improved.

scholarly journals Mean grain diameters from thin sections: matching the average to the problem

2017 ◽  
Vol 81 (3) ◽  
pp. 515-530 ◽  
Author(s):  
Robert S. Farr ◽  
Victoria C. Honour ◽  
Marian B. Holness
Keyword(s):  
Size Distribution ◽  
Thin Section ◽  
Continuous Process ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Spherical Particles ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Thin Sections ◽  
Wide Range

AbstractIt is common practice to estimate a mean diameter for spherical or sub-spherical particles or vesicles in a rock by multiplying the average diameter of the approximately circular cross-sections visible in thin section by a factor of 1.273. This number-weighted average may be dominatedby the hard-to-measure fine tail of the size distribution, and is unlikely to be representative of the average particle diameter of greatest interest for a wide range of geological problems or processes. Average particle size can be quantified in a variety of ways, based on the mass or surfacearea of the particles, and here we provide exact relations of these different average measures to straightforward measurements possible in thin section, including an analysis of how many particles to measure to achieve a desired level of uncertainty. The use of average particle diameter isillustrated firstly with a consideration of the accumulation of olivine phenocrysts on the floor of the 135 m thick picrodolerite/crinanite unit of the Shiant Isles Main Sill. We show that the 45 m thick crystal pile on the sill floor could have formed by crystal settling within about a year.The second geological example is provided by an analysis of the sizes of exsolved Fe-rich droplets during unmixing of a basaltic melt in a suite of experimental charges. We show that the size distribution cannot be explained by sudden nucleation, followed by either Ostwald ripening or Browniancoalescence. We deduce that a continuous process of droplet nucleation during cooling is likely to have occurred.

Cellular Concrete with Addition of Aluminum Recycled Foil Powders

2005 ◽  
Vol 498-499 ◽  
pp. 198-204 ◽  
Author(s):  
Edval G. de Araújo ◽  
Jorge Alberto Soares Tenório
Keyword(s):  
Aluminum Powder ◽  
Raw Materials ◽  
Average Particle Size ◽  
Aluminum Foil ◽  
High Energy ◽  
Spherical Particles ◽  
Average Particle ◽  
Cost Component ◽  
Time Required ◽  
Cellular Concrete

Considering its advantage of low density and favorable insulation properties, there are several applications for lightweight autoclaved aerated concrete of uniform cellular structure.The raw materials for the manufacturing of cellular concrete are Portland cement, finely grounded sand and lime. These are batched and mixed with water and metallic aluminum powder finely divided. There is a reaction between the aluminum powder and hydroxides forming millions of hydrogen bubbles throughout the mixture.The aluminum powder is the highest cost component, and the objective of this work is replacing it for another gas forming agent, like recycled foil.The foils are grinded in a high energy ball mill (attritor). Quartz sand is mixed with aluminum foil to reduce the time required for grinding, obtaining spherical particles and ensuring a uniform distribution of aluminum in the gas forming agent.The activity of this gas forming agent was determined by the gas volumetric technique. Average particle size and compressive strength of the samples were measured. The relationship between volume of the gas released during the reaction and milling conditions are presented, showing its viability for producing a high quality cellular concrete.

scholarly journals CPT - DR - D50 correlations of sands for liquefaction potential analysis

2020 ◽  
Vol 156 ◽  
pp. 02017
Author(s):  
A Hakam ◽  
S Warzuqni ◽  
BM Adji ◽  
Junaidi ◽  
IF Muharani ◽  
...  
Keyword(s):  
Particle Size ◽  
Relative Density ◽  
Average Particle Size ◽  
Physical And Mechanical Properties ◽  
Main Stage ◽  
Average Particle ◽  
Liquefaction Potential ◽  
Sand Deposit ◽  
The Relationship ◽  
Cpt Test

Liquefaction assessment is the main stage in determining the potential liquefaction in a certain site. In order to assess the potential liquefaction, the values of physical and mechanical properties of the soil are very important. Two main parameters that are essentially needed to determine the liquefaction potential in a sand deposit; those are relative density and men particle size. In Indonesia, CPT is a testing method that is very practically famous and often conducted in the field. Assessment of Liquefaction Potential will be cheap and valuable by using the results of the CPT test. For this reason, this paper describes the results of conducted research to obtain the values of the relative density and mean particle size based on the outcomes of the CPT test: those are cone resistance (qc) and friction ration (Rf). The relationship between qc-Rf and Dr-D50 is accelerated by conducting a series of tests on soil samples with variations in the value of relative density and average particle size. The test results are plotted in a graph as well as in the terms of mathematical formulations to figure out for the relationship between CPT values and Dr-D50 in detail for sands. This research is very useful to assess the liquefaction potential in a particular area with very satisfying results

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