Showing 4 results for Akhlaghi
Akhlaghi F., Zahedi H., Sharifi M.,
Volume 1, Issue 2 (Jan 2004)
Abstract
In this study different volume fractions of SiC particles of various sizes were introduced into the semisolid A356 aluminum alloy by a mechanical stirrer. Then the slurry was poured into a permanent die of certain dimensions either when the metal alloy was partially solid (semisolid-semisolid or SS route) or after reheating to above the liquidus temperature of the alloy (semisolid-liquid or SL route). Both the SS and SL composite samples were solution-treated at 520°C for 8 hours followed by quenching in water at room temperature. Microstructural characterization studies have been conducted on both the SL and SS samples to quantify the effects of the size andcontent of the SiC particles as well as the solutionizing treatment on the morphology and size ofthe eutectic silicon particles and the matrix grain (globule) size. The results were rationalized in terms of the different nucleation, fragmentation, spherodization and coarsening events, which had taken place during the processing of these composites. Finally the impact of these microstructural features in improving the wear properties of the composites has been discussed.
A. H. Shafie Farhood, F. Akhlaghi,
Volume 7, Issue 1 (winter 2010 2010)
Abstract
Abstract:
structures in alloys. This method is based on pouring the melt through a small sized nozzle into a mould located at a
certain height under the crucible. This simple method generates globular structures without using equipments such as
impellers, electromagnetic stirrers, ultrasonic probes and cooling slopes. Therefore it is cost effective. In the present
study, the effect of casting size and mould casting modulus on the globular structure evolution in A356 aluminium alloy
specimens prepared by NMS process was investigated. The results showed that regardless of the different casting
modulus and their sizes, all the specimens exhibited globular structures. However, the size and shape factor of the
globules decreased with increased casting modulus and casting size indicating the influential effect of the surface area
of the mould in generating globular structures in this process.
Narrow Melt Stream (NMS) is a relatively new semisolid metal processing technique for producing globular
N. Akhlaghi, G. Najafpour, M. Mohammadi,
Volume 17, Issue 4 (December 2020)
Abstract
Modification of MnFe2O4@SiO2 core-shell nanoparticles with (3-aminopropyl) triethoxysilane (APTES) was investigated. The magnetite MnFe2O4 nanoparticles with an average size of ~33 nm were synthesized through a simple co-precipitation method followed by coating with silica shell using tetraethoxysilane (TEOS); that has resulted in a high density of hydroxyl groups loaded on nanoparticles. The prepared MnFe2O4@SiO2 nanoparticles were further functionalized with APTES via silanization reaction. For having suitable surface coverage of APTES, controlled hydrodynamic size of nanoparticles with a high density of amine groups on the outer surface, the APTES silanization reaction was investigated under different reaction temperatures and reaction times. Based on dynamic light scattering (DLS) and zeta potential results, the best conditions for the formation of APTES-functionalized MnFe2O4@SiO2 nanoparticles were defined at a reaction temperature of 70 °C and the reaction time of 90 min. The effectiveness of our surface modification was established by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). The prepared magnetite nanostructure can be utilized as precursors for synthesizing multilayered core-shell nanocomposite particles for numerous applications such as medical diagnostics, drug, and enzyme immobilization, as well as molecular and cell separation.
Farideh Golbabaie, Somayeh Farhang Dehghan, Majid Habibi Mohraz, Elham Akhlaghi Pirposhteh,
Volume 18, Issue 4 (December 2021)
Abstract
The present study aims to investigate the role of the electrostatic mechanism in the filtration process of Polyacrylonitrile nanofibers containing single-walled carbon nanotube. The nanofibers were fabricated via electrospinning using 16wt% Polyacrylonitrile polymer (PAN) solution, single-wall carbon nanotubes (SWNT) at a ratio of 99:1 along with N and N-Dimethylformamide solvents. Initial filtration efficiency was tested as per ISO 29463:2011 standard inside a test rig. An electrostatic discharge test was performed via the chemical treatment of the filter media with Isopropyl alcohol in accordance to EN779 standard. Mean initial filtration efficiency of the nanofiber media in the capturing of 100nm and 200nm particles were 95.92% ±2.74 and 97.26% ±1.11 respectively, while for particles between 80nm to 250nm, this was 96.73% ±2.74. The efficiency of the untreated media was 0.2% to 1.2% higher than the PAN/SWNT media after electron discharge using Isopropyl alcohol with an even bigger difference being observed at lower particle size ranges. After treatment with Isopropyl alcohol, the pressure drop of the filtration media was increased from 164.7 Pa to 185.3 Pa. The reduction in filtration efficiency observed after the electrostatic discharge test indicates that the electrical charge of the electrospun nanofibers is influential in its initial efficiency for removing the submicron particles.
