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pelaseyed--sogol
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Fabrication of Al /Al3Ti in-situ Composite by Mechanical Alloying and Two-Step Hot Press
, M.Sc. Thesis Sharif University of Technology ; Maddah Hosseini, Hamid Reza (Supervisor)
Abstract
Al /Al3Ti in-situ composite have been fabricated by mechanical alloying and two-step hot pressing of powders containing Al and 20%wt Ti. Samples were characterized by using optical microscopy, density measurement, brinel hardness, XRD analysis. An increasing density was observed with increasing pressure until certain pressure and after that the density of composite decreased, which can be attributed to the increase in the level of porosity level and the amount of forming Al3Ti. The samples that hot pressed under cycle 5 and 6, showed the most volume fraction of in-situ phases on the matrix. The wear behavior of Al based composites reinforced with in situ Al3Ti particles has been investigated...
Investigation of the Shaft Failure Connected to Extruder
, Article Journal of Failure Analysis and Prevention ; Volume 15, Issue 6 , 2015 , Pages 775-781 ; 15477029 (ISSN) ; Mashayekhi, F ; Movahedi-Rad, A ; Sharif University of Technology
Springer New York LLC
2015
Abstract
In this study, the failure analysis of a shaft of a unit, which had been failed during the service, was studied. This shaft was welded to the blades, and their chemical compositions were determined by spectroscopy method. In order to determine the root cause of failure and contribution factors, different investigation methods including visual examination, optical microscopy and scanning electron microscope analysis, and hardness test were carried out. It was concluded that the shaft was failed due to fatigue. The failure was caused by improper welding of blades to the shaft. At the end, in order to prevent or decelerate such failure, some recommended remedies were suggested
Failure analysis of gas turbine burner tips
, Article Engineering Failure Analysis ; Volume 99 , 2019 , Pages 7-17 ; 13506307 (ISSN) ; Attarian, M ; Kermajani, M ; Abdi, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, the causes of failure in gas turbine burner tips were investigated. For this purpose, two burner tips used in a petrochemical company with different failure evidence as well as service times were inspected. These parts showed signs of deterioration such as multiple cracks, corrosion, and wear following 4000 h and 8000 h operations. The examinations included chemical composition analysis using optical emission spectroscopy (OES), stereo-, optical-, and scanning electron microscopy studies, and macro/micro-hardness measurements. These investigations revealed high thermal stresses to be the main failure cause of the burner tips. Moreover, due to flame inclination, a local...
A novel pathway to produce biodegradable and bioactive PLGA/TiO2 nanocomposite scaffolds for tissue engineering: Air–liquid foaming
, Article Journal of Biomedical Materials Research - Part A ; Volume 108, Issue 6 , 2020 , Pages 1390-1407 ; Madaah Hosseini, H. R ; Samadikuchaksaraei, A ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
Poly (lactate-co-glycolate) (PLGA) is a typical biocompatible and biodegradable synthetic polymer. The addition of TiO2 nanoparticles has shown to improve compressive modulus of PLGA scaffolds and reduced fast degradation. A novel method has been applied to fabricate PLGA/TiO2 scaffolds without using any inorganic solvent, with aim of improving the biocompatibility, macroscale morphology, and well inter-connected pores efficacy: Air–Liquid Foaming. Field Emission Scanning Electron Microscopy (FESEM) revealed an increase in interconnected porosity of up to 98%. As well the compressive testing showed enhancement in modulus. Bioactivity and in vitro degradation were studied with immersion of...
PLGA/TiO2 nanocomposite scaffolds for biomedical applications: Fabrication, photocatalytic, and antibacterial properties
, Article BioImpacts ; Volume 11, Issue 1 , 2021 , Pages 45-52 ; 22285652 (ISSN) ; Madaah Hosseini, H. R ; Nokhbedehghan, Z ; Samadikuchaksaraei, A ; Sharif University of Technology
Tabriz University of Medical Sciences
2021
Abstract
Introduction: Porous 3D scaffolds synthesized using biocompatible and biodegradable materials could provide suitable microenvironment and mechanical support for optimal cell growth and function. The effect of the scaffold porosity on the mechanical properties, as well as the TiO2 nanoparticles addition on the bioactivity, antimicrobial, photocatalytic, and cytotoxicity properties of scaffolds were investigated. Methods: In the present study, porous scaffolds consisting poly (lactide-co-glycolide) (PLGA) containing TiO2 nanoparticles were fabricated via air-liquid foaming technique, which is a novel method and has more advantages due to not using additives for nucleation compared to former...
Fabrication and Characterization of Bioactive PLGA- TiO2 Nanocomposite Scaffold by Air-liquid Foaming for Bone Tissue Engineering
, Ph.D. Dissertation Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor) ; Samadi Kuchaksaraei, Ali (Co-Supervisor)
Abstract
Poly (lactate-co-glycolate) is a typical biocompatible and biodegradable synthetic polymer. Addition of TiO2 nanoparticles improved compressive modulus of PLGA scaffolds and reduced fast degradation. Porous 3D scaffolds, which are synthesized using biocompatible and biodegradable materials, could provide suitable microenvironment and mechanical support for optimal cell growth and function. A novel method has been applied to fabricate PLGA/TiO2 scaffolds without using any organic solvent or porogen for nucleation compared to former ways, with aim of improving the biocompatibility, macroscale morphology and well inter-connected pores efficacy: Air-Liquid Foaming. Adjustment of the foaming...