scholarly journals Effects of CeO2 on the Si Precipitation Mechanism of SiCp/Al-Si Composite Prepared by Powder Metallurgy

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4365
Author(s):  
Bin Yang ◽  
Aiqin Wang ◽  
Kunding Liu ◽  
Chenlu Liu ◽  
Jingpei Xie ◽  
...  
Keyword(s):  
Particle Size ◽  
Powder Metallurgy ◽  
Nucleation Rate ◽  
Heterogeneous Nucleation ◽  
Theoretical Calculations ◽  
Average Particle Size ◽  
Average Particle ◽  
Powder Metallurgy Method ◽  
Precipitation Mechanism ◽  
Average Size

SiCp/Al-Si composites with different CeO2 contents were prepared by a powder metallurgy method. The effect of CeO2 content on the microstructure of the composites was studied. The mechanism of CeO2 on the precipitation of Si during sintering was analyzed by theoretical calculations. The results show that the appropriate amount of CeO2 can significantly refine the size of precipitated Si particles in the composite and increase the number of Si particles. With the increase of CeO2 content from 0 to 0.6 wt%, the number of Si particles precipitated in the composites increases gradually, and the average particle size of Si particles decreases gradually. When the CeO2 content is 0.6 wt%, the number of Si particles precipitated in the composites reaches the maximum, and the average particle size reaches the minimum. However, with the increase of CeO2 content from 0.6 wt% to 1.8 wt%, the number of Si particles precipitated in the composites began to decrease, and the average size of Si particles gradually increased. CeO2 can be used as heterogeneous nucleation substrate of precipitated Si, and the nucleation rate of precipitated Si on a CeO2 substrate is higher than that on an aluminum substrate. The proper addition of CeO2 can improve the nucleation efficiency of precipitated Si, thus increasing the amount and refining the size of precipitated Si.

Effects of MgO Nano Particles on Microstructural and Mechanical Properties of Aluminum Matrix Composite prepared via Powder Metallurgy Route

2012 ◽  
Vol 05 ◽  
pp. 607-614 ◽  
Author(s):  
Mohammad Amin Baghchesara ◽  
Hossein Abdizadeh ◽  
Hamid Reza Baharvandi
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Powder Metallurgy ◽  
Volume Fraction ◽  
Average Particle Size ◽  
Aluminum Matrix ◽  
Nano Particles ◽  
Aluminum Matrix Composites ◽  
Average Particle ◽  
Powder Metallurgy Method

The objective of the present investigation was to evaluate the microstructural and mechanical properties of Al /nano MgO composite prepared via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1μm and MgO particulate with an average particle size between 60 to 80 nm were used. Composites containing 1.5, 2.5 and 5 percent of volume fraction of MgO were prepared by powder metallurgy method. The specimens were pressed by Cold Isostatic Press machine (CIP), subsequently were sintered at 575, 600 and 625°C. After sintering and preparing the samples, mechanical properties were measured. The results of microstructure, compression and hardness tests indicated that addition of MgO particulates to aluminum matrix composites improves the mechanical properties.

scholarly journals Effect of the polymeric coating over Fe3O4 particles used for magnetic separation

2010 ◽  
Vol 8 (5) ◽  
pp. 1041-1046 ◽  
Author(s):  
Raúl Reza ◽  
Carlos Martínez Pérez ◽  
Claudia Rodríguez González ◽  
Humberto Romero ◽  
Perla García Casillas
Keyword(s):  
Particle Size ◽  
Magnetite Nanoparticles ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Polymeric Coating ◽  
Average Particle ◽  
Synthesis Conditions ◽  
Aging Conditions ◽  
Magnetite Particles ◽  
Average Size

AbstractIn this work, the synthesis of magnetite nanoparticles by two variant chemical coprecipitation methods that involve reflux and aging conditions was investigated. The influence of the synthesis conditions on particle size, morphology, magnetic properties and protein adsorption were studied. The synthesized magnetite nanoparticles showed a spherical shape with an average particle size directly influenced by the synthesis technique. Particles of average size 27 nm and 200 nm were obtained. When the coprecipitation method was used without reflux and aging, the smallest particles were obtained. Magnetite nanoparticles obtained from both methods exhibited a superparamagnetic behavior and their saturation magnetization was particle size dependent. Values of 67 and 78 emu g−1 were obtained for the 27 nm and 200 nm magnetite particles, respectively. The nanoparticles were coated with silica, aminosilane, and silica-aminosilane shell. The influence of the coating on protein absorption was studied using Bovine Serum Albumin (BSA) protein.

Preparation of Cr2O3 Nanoparticles via Hydrothermal Reduction of CH3OH

2012 ◽  
Vol 463-464 ◽  
pp. 760-763
Author(s):  
Zhen Zhao Pei ◽  
Hong Bin Xu ◽  
Yi Zhang
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Average Particle Size ◽  
Average Particle ◽  
Calcination Temperatures ◽  
Cr2o3 Nanoparticles ◽  
Average Size ◽  
Hydrothermal Reduction ◽  
Scanning Electron

Nanoparticles of Cr2O3 were successfully obtained via hydrothermal reduction of CH3OH. The oxidant and chromium source was CrO3. The process needs no stirrer or surfactant and the CrO3 concentration was 0.83mol/L. The obtained products were loosely agglomerated Cr2O3 nanoparticles with the average size of 29 to 79 nm. Influences of reactant ratios and calcination temperatures on the specific surface area and average particle size were discussed. And the morphology of nanoparticles was investigated by use of field-emission scanning electron microscope.

Synthesis of Nano-Sized Barium Titanate Powder by Rotary-Hydrothermal Process

2009 ◽  
Vol 421-422 ◽  
pp. 269-272
Author(s):  
Takashi Kubo ◽  
Masayuki Hogiri ◽  
Hiroshi Kagata ◽  
Atsushi Nakahira
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Hydrothermal Process ◽  
Water System ◽  
Starting Material ◽  
Average Particle ◽  
Rotary Speed ◽  
Average Size ◽  
Faceted Particles

Nano-sized BaTiO3 powders with narrow size distribution and the high tetragonality were attempted to synthesize by the rotary-hydrothermal process in water system, using two kinds of commercial anatase-type TiO2 (ST21/ST01) with different particle size and Ba(OH)2. The rotary-hydrothermal syntheses were done with the rotary-speed of 20 revolutions per minute at 523 K for 24 h. Highly- and mono-dispersed BaTiO3 powders were successfully synthesized by applying the rotary-hydrothermal process. For rotary-hydrothermal synthesis, it was found that the average size, tetragonality, and quality of the BaTiO3 particle strongly depended on the particle size of the starting material. In the case of using ST01 as a starting material, BaTiO3 nano-powders mainly composed of coarse-faceted particles (average particle size = ca.100 nm) with the tetragonal phase and very little lattice defects were successfully synthesized.

Preparation and Characterization of Gold Nanoparticles in the Presence of Citrate and Soybean Seed Extract in an Acidic Conditions

Drug Research ◽  
2017 ◽  
Vol 67 (05) ◽  
pp. 266-270 ◽  
Author(s):  
Ebrahim Izadi ◽  
Ali Rasooli ◽  
Abolfazl Akbarzadeh ◽  
Soodabeh Davaran
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Size Distribution ◽  
Average Particle Size ◽  
Soybean Seed ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Soybean Extract ◽  
Average Size

AbstractThrough the present study, an eco-friendly method was used to synthesize the gold nanoparticles (GNPs) by using the sodium citrate and extract of the soybean seed as reducing the agents at PH 3. X-Ray diffraction (XRD) method was used to evaluate the crystal structure of as-synthesized NPs and it’s revealed that this method leads to well crystallized GNPs. In order to determine the particle size and their distribution, field emission scanning microscopy (FE-SEM) and dynamic light scattering (DLS) were used. The results showed that, the average particle size distribution of synthesized GNPs in solutions containing of the soybean extract and 1% citrate at PH 3 is about 109.6 and 140.9 nm, respectively. Also, we find that the average size of GNPs is 40 and 33 nm from solutions of citrate and soybean extract, respectively. It was concluded that using the extract of soybean seeds as reducing agent can lead to GNPs with small size and narrow size distribution.

Milling Duration Influence on Strontium Hexaferrite Technological Characteristics

2021 ◽  
Vol 410 ◽  
pp. 730-734
Author(s):  
Ivan N. Egorov ◽  
Nikolay Ya. Egorov ◽  
Svetlana I. Egorova
Keyword(s):  
Particle Size ◽  
Powder Metallurgy ◽  
Bulk Density ◽  
Fluidized Bed ◽  
Average Particle Size ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Actual Problem ◽  
Technological Characteristics ◽  
Milling Duration

Fine powders of strontium hexaferrite are widely used in powder metallurgy for the production of permanent magnets resistant to atmospheric oxygen and high working temperatures. Obtaining powders with predefined technological characteristics in minimal time and with minimal energy consumption is an actual problem of powder metallurgy. The paper provides the results of experimental studies of technological characteristics of strontium hexaferrite powder (SrFe12O19) during milling in a beater mill. Mechanical milling of coarse strontium hexaferrite was carried out in the mill with the system of rotating beaters for 120 minutes without and with the creation of a pseudo fluidized bed. The fluidization was formed by a perpendicular constant and alternating magnetic field with induction gradients of 150 and 210 mT/m. Average particle size and powder bulk density dependencies from milling time were studied. Experimental data show that milling with the formation of a magneto fluidized bed allows intensifying the process. Beginning from 70 minutes, the dependencies of average particle size and bulk density come to almost asymptotic behavior making further milling rather ineffective. Carried out research allows choosing optimal milling duration for obtaining the required average particle size.

Formation of metal-carbon nanocomposites based on Cu-Fe alloy nanoparticles and carbonized polyacrylonitrile

2021 ◽  
Vol 1 ◽  
pp. 58-66
Author(s):  
A.A. Vasilev ◽  
◽  
E.L. Dzidziguri ◽  
M.N. Efimov ◽  
D.G. Muratov ◽  
...  
Keyword(s):  
Particle Size ◽  
Carbon Nanostructures ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Carbon Matrix ◽  
Synthesis Temperature ◽  
Average Particle ◽  
Synthesis Of Nanoparticles ◽  
Fe Nanoparticles ◽  
Average Size

A method for the synthesis of nanoparticles of the Cu-Fe bimetallic system with limited mutual solubility of the components is proposed. The synthesis method consists of a one-stage process of IR pyrolysis of precursors in the form of films obtained from a joint solution of polyacrylonitrile and hydrates-nitrates of iron and copper. The effect of the synthesis temperature on the structure formation of the nanocomposites and the phase composition of bimetallic Cu-Fe nanoparticles dispersed in the carbon matrix was studied. The analysis showed a simultaneous presence of Fe and Cu phases in nanocomposites, presumably with a low solubility of the components. The average particle size is 14-17 nm and changes insignificantly with an increase in the synthesis temperature from 400 to 700°C. An increase in the synthesis temperature to 800°C led to a broadening of the particle size distribution and the increase in the average size. The formation of complex carbon nanostructures on Cu-Fe nanoparticles is found.

Fabrication of Nano-Sized Tin Oxide Powder by Spray Pyrolysis Process

2009 ◽  
Vol 1174 ◽  
Author(s):  
Jaekeun Yu ◽  
Jwayeon Kim ◽  
Jeoungsu Han
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Reaction Temperature ◽  
Tin Oxide ◽  
Average Particle Size ◽  
Raw Material ◽  
Nano Particles ◽  
Average Particle ◽  
Average Size ◽  
20 Nm

AbstractBy using tin chloride solution as the raw material, a nano-sized tin oxide powder with average particle size below 50 nm is generated by spray pyrolysis reaction. This study also examines the influences of the reaction parameters such as reaction temperature and the concentration of raw material solution on the powder properties. As the reaction temperature increases from 800 to 850 ℃, the average particle size of the generated powder increases from 20 nm to 30 nm. As the reaction temperature reaches 900 ℃, the droplets are composed of nano-particles with average size of 30 nm, while the average size of individual particles increases remarkably up to 80˜100 nm. When the tin concentration reaches 75 g/L, the average particle size of the powder is below 20 nm. When the tin concentration reaches 150 g/L, the droplets are composed of nano particles with average size around 30 nm, whereas the average size of independent particles increases up to 80˜100 nm. When the concentration reaches 400 g/L, the droplets are composed of nano-particles with average size of 30 nm.

scholarly journals Preparation of W-C-Co Composite Micropowder with Spherical Shaped Particles Using Plasma Technologies

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4258
Author(s):  
Andrey Samokhin ◽  
Nikolay Alekseev ◽  
Aleksey Astashov ◽  
Aleksey Dorofeev ◽  
Andrey Fadeev ◽  
...  
Keyword(s):  
Particle Size ◽  
Plasma Treatment ◽  
Average Particle Size ◽  
Spherical Particles ◽  
Average Particle ◽  
Dense Microstructure ◽  
Scale Range ◽  
Powder Particles ◽  
Phase And Chemical Composition ◽  
Average Size

The possibility of obtaining composite micropowders of the W-C-Co system with a spherical particle shape having a submicron/nanoscale internal structure was experimentally confirmed. In the course of work carried out, W-C-Co system nanopowders with the average particle size of approximately 50 nm were produced by plasma-chemical synthesis. This method resulted in the uniform distribution of W, Co and C among the nanoparticles of the powder in the nanometer scale range. Dense microgranules with an average size of 40 microns were obtained from the nanopowders by spray drying. The spherical micropowders with an average particle size of 20 microns were received as a result of plasma treatment of 25.36 microns microgranule fraction. The spherical particles obtained in the experiments had a predominantly dense microstructure and had no internal cavities. The influence of plasma treatment process parameters on dispersity, phase, and chemical composition of spherical micropowders and powder particles microstructure has been established.

Characteristics of titanium nano-oxide (IV) as potent polymethyl metacrylate modifier

2017 ◽  
Vol 67 (1) ◽  
pp. 4-17 ◽  
Author(s):  
Mariusz Cierech ◽  
Jacek Wojnarowicz ◽  
Adam Kolenda ◽  
Witold Łojkowski ◽  
Elżbieta Mierzwińska-Nastalska ◽  
...  
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Average Particle Size ◽  
Specific Area ◽  
Acrylic Resin ◽  
Average Particle ◽  
Denture Base ◽  
Denture Stomatitis ◽  
Study Characteristics ◽  
Average Size

Introduction. The aging of the population, as is currently observed, has wide-ranging implications. One of them is an increasing demand for prosthetic treatment of old people with missing teeth using acrylic partial or complete dentures. A denture base made of polymethyl metacrylate (PMMA) creates specific conditions in the oral cavity that predispose patients to develop denture stomatitis complicated by fungal infection. Attempts have recently been made to modify the surface of polymerized acrylic resin by a hydrophilic layer that disrupts the adhesion of microorganisms or to modify the whole chemical composition. In the era of nanotechnology it is reasonable to look for chemical nanocompounds with the intention of incorporating tchem into PMMA and to use their microbiological properties. Aim of the study. Characteristics of nanoparticles (NPs) of titanium dioxide (TiO2) before their potential use as a modifier for PMMA as an alternative material for denture bases. Material and methods. TiO2 nanoparticles (Lot No: SHY-179, Promethean Particles Ltd., UK) were used as the experimental material. The average size and size distribution of the crystallites were determined by X-ray powder diffraction (XRD). The density of NPs was determined by helium pycnometer and a specific area using the linear equation form isotherm BET (Brunauer-Emmett-Teller). The average particle size was determined by the calculation results of the specific surface area and density. The NP. morphology is based on images from a scanning electron microscope (SEM). Results. Tested TiO2 – NPs had an average particle size of about 9 nm, a mean crystallite size of 5-6 nm, a density of 3.16 g/cm3 and a surface area of 215 m2/g. SEM studies showed high homogeneity of the nanoparticles, both in size and shape. Conclusions. Properties of characterized NPs and the research results of other authors presented in this publication give us a reason to believe that a possible incorporation of NPs into polymethyl methacrylate will activate the antifungal function.

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