Showing 4 results for Goodarzi
M. Ebrahimi-Basabi,, J. Javadpour,, H. Rezaie, M. Goodarzi,
Volume 6, Issue 1 (winter 2009 2009)
Abstract
Abstract: Nano- size alumina particles have been synthesized by mechanical activation of a dry powder mixture of
AlCl3 and CaO. Mechanical milling of the above raw materials with the conditions adopted in this study resulted in
the formation of a mixture consisting of crystalline CaO and amorphous aluminum chlorides phases. There was no
sign of chemical reaction occurring during milling stage as evidenced by x-ray diffraction studies. Subsequent heat
treatment of the milled powder at 350ºC resulted in the occurrence of displacement reaction and the formation of
Al2O3 particles within a water soluble CaCl2 matrix. The effect of higher temperature calcinations on the phase
development in this powder mixture was followed by X-ray diffraction (XRD) analysis and scanning electron
microscope ( SEM). Differential thermal analysis (DTA) was used to compare the thermal behavior between the
milled and unmilled powders. Perhaps the most important result in this study was the observation of á-Al2O3 phase
at a very low temperature of 500ºC.
M. Goodarzi, S. M. A. Boutorabi, M. A. Safarkhanian,
Volume 6, Issue 3 (Summer 2009 2009)
Abstract
Abstract:In this study, an effort has been made to determine the influence of rotational speed of tool on themicrostructure and hardness values of friction stir welded 2024-T851 aluminum alloy. The microstructure of stir zonein the joints has been investigated. It was found that the particles such as Al6(CuFeMn) particles are broken up duringfriction stir welding, and the degree of break up of these particles in the stir zone increases with increasing rotationalspeed. Since the break up of these particles and the recrystallization of new grains happen simultaneously, the brokenparticles would be placed in the grain boundaries. Moreover, the hardness value in the stir zone increases withincreasing rotational speed
M.r. Tavakoli Shoushtari, M. Goodarzi, H. Sabet,
Volume 15, Issue 4 (December 2018)
Abstract
In this study, the microstructure, hardness, and dry sliding wear behavior of the hardfaced layers made by a cored wire Fe-B-C-Ti alloy were investigated. St37 steel was used as the substrate and the deposition of the hardfaced layers was conducted by the flux cored arc welding (FCAW) process under single-, two-, and three-pass conditions. Dry sliding wear tests were performed by a pin-on-disk apparatus, based on ASTM-G99, at room temperature (250C) at the normal applied loads of 50, 100, and 150 N with a constant speed of 0.08 m/s for a sliding distance of 1000 m. The microstructural and phase analyses were carried out by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD), respectively. The results showed that the hardfaced layer produced by the single-pass process contains TiC rectangular phase distributed within a matrix containing ferrite and the eutectic of (α-Fe2B). But, the hardfaced layers produced by the two- and three-pass process contain TiB2 hexagonal phase in addition to TiC, which prevents the formation of detrimental FeB phase around Fe2B and reduces the number of micro-cracks. Moreover, the sample hardfaced by the three-pass process had the best wear resistance due to the greater hardness resulted from the higher amounts of TiC and TiB2 phases. In addition, increasing the number of passes has led to the reduction of wear rate at all the three applied loads. At the applied load of 100 N, the wear mechanism for the all three hardfaced samples was an oxidation wear. However, at the applied load of 150 N, the wear mechanism was a combination of oxidation and delamination.
A. Khalili, M. Mojtahedi, M. Goodarzi, M. J. Torkamani,
Volume 16, Issue 3 (September 2019)
Abstract
The aim of this work was to synthesize TiC reinforced coating on carbon steel via reduction of ilmenite powder. A mixture of ilmenite and graphite was pre-placed on AISI 1020 steel surface. The effect of the addition of excess graphite amounts on the progress of synthesis of carbide particles was studied. The evolution of phases in different coatings was analysed via X-ray diffraction and scanning electron microscopy. Then again, the initial powder mixtures were mechanically activated for various durations, to accelerate the reactions in transient melt pool. Finally, the Fe-TiC hard coating was successfully synthesized by carbothermic reduction of ilmenite through laser surface treatment. Moreover, it is proved that combination of mechanical activation with additive laser melting effectively improves the level of ilmenite reduction, besides enhancing the distribution of hard particles and the hardness of the coatings to more than 1300 HV.
