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- 저자 : S. Soltan (검색결과 5 건)
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Effect of Ce Addition on the Tribological Behavior of ZK60 Mg-Alloy
S. M. Banijamali,Y. Palizdar,S. Najafi,A. Sheikhani,M. Soltan Ali Nezhad,P. Valizadeh Moghaddam,H. Torkamani 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8
The present work aims to study the tribological behavior of an extruded ZK60 alloy in the presence of Ce; in a previous study, among ZK60 alloys with diferent Ce addition rates, an alloy with 3 wt% of Ce was found to exhibit the mostpromising mechanical (e.g., hardness and strengths) properties, while its wear behavior remained unknown. The results ofmicrostructural examinations by optical and electron microscopes show that Ce addition reduces the grain size from 6.1 to2.0 μm. Besides, in addition to the precipitates already distributed in the base alloy (Mg7Zn3), Ce could promote the formation of a new precipitate (MgZn2Ce), increasing the total fraction of the precipitates. These microstructural evolutionsenhance the strengths of the studied ZK60 alloy, as the yield and tensile strengths increase from 212 to 308 MPa and from297 to 354 MPa, respectively. A pin on disc tribometer was employed to study the wear behavior of the developed alloyunder diferent normal loads (5, 20, 40, and 60 N). The results show that the base and Ce-added alloys exhibit almost asimilar frictional behavior, while the wear resistance of the Ce-added alloy is higher within the load ranges applied: (i) inlow load conditions (5 and 20 N), where the abrasive wear is the active mechanism, the precipitates in the Ce-added alloycould enhance the wear resistance. (ii) Under the load of 40 N, oxidative wear is also an operative wear mechanism, leadingto a sharp increase in the wear rate of the alloys. In this condition, Ce could provide a protective oxide layer, which couldimprove the wear resistance of the alloy. (iii) At a load of 60 N, both studied alloys exhibit a similar wear rate due to a severeoxidation condition. Therefore, beyond this loading condition, the microstructural evolutions (e.g., change in precipitationbehavior) caused by Ce addition can no longer contribute to the enhancement of wear resistance.
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Role of Some Benzohydrazide Derivatives as Corrosion Inhibitors for Carbon Steel in HCl Solution
Fouda, A.S.,Mohamed, M.T.,Soltan, M.R. The Korean Electrochemical Society 2013 Journal of electrochemical science and technology Vol.4 No.2
Corrosion inhibition of carbon steel in 2M HCl by some benzohydrazide derivatives (I-III) was studied using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques at $30^{\circ}C$. Polarization studies showed that all the investigated compounds are of mixed type inhibitors. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the hydrazide derivatives, probably implying that physical adsorption of cationic species may be responsible for the observed inhibition behavior. Electrochemical impedance studies showed that the presence of benzohydrazide derivatives decreases the double layer capacitance and increases the charge transfer resistance. The adsorption of these compounds on carbon steel surface was found to obey Temkin's adsorption isotherm. Synergistic effects increased the inhibition efficiency in the presence of halide additives namely KI and KBr. An inhibition mechanism was proposed in terms of strongly adsorption of inhibitor molecules on carbon steel surface.
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M. El-Hagary,S. Soltan,M. Emam-Ismail,S. Althoyai 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
This study reports the structure and the magnetic properties of Zn1−xNixS nanocrystalline filmswith Ni composition ratios of 0.05 x 0.2. Thin films of Zn1−xNixS were deposited on Corningglass substrates by using an electron-beam evaporation method. X-ray diffraction patterns revealedsingle- phase films with a cubic zinc-blend-type structure with preferred crystallographic orientationsalong the (111) and the (220) planes. Evidence for the nanocrystalline nature of the films wasobserved from the investigations of the surface morphology by using scanning electron microscopyand atomic force microscopy. Magnetic domains were observed by using magnetic force microscopyat room temperature, indicating the existence of ferromagnetism over the film’s surface. The magneticmeasurements at 5 K revealed a superparamagnetic behavior. However, room-temperatureferromagnetism was observed in all the nanocrystalline Zn1−xNixS films. The saturation magnetizationfor the Zn1−xNixS films was found to increase with increasing dopant concentration (x). Anexchange interaction between local spin-polarized electrons (Ni2+ ions) and conductive electronsaccording to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mechanism is proposed as apossible mechanism for the ferromagnetism. These results show that the Ni-doped ZnS nanocrystallinefilms are promising materials for applications in spintronic and magnetic sensor devices.
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A. Abu El-Fadl,A.S. Soltan,M.A. Hefni,N.M. Shaalan 한국물리학회 2008 Current Applied Physics Vol.8 No.2
Results of indentation-induced hardness testing studies on potassium zinc chloride crystals doped with Li+ ions, leading to an under-standing of their mechanical behaviour, are presented. The Vickers hardness of these crystals for (100), (010) and (001) planes in theload range 20160 g were studied. Load-independent values of hardness are estimated for the three crystallographic planes by applyingHays-Kendall’s and Li-Bradt models. The results showed that: (1) for the three crystallographic planes the load-independent hardnessplane is higher than that of both (10) and (010) planes, (3) the values of load-independent hardness depend on Li+ concentrations inthe K₂ZnCl₄crystals, (4) the variations of crack length and crack morphology are described for studied crystal planes.
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