نتایج جستجو برای: lower corrosion current density and higher coating corrosion resistance than the other composite formulations this nanocomposite provided superior protection against corrosion in sodium chloride solution

تعداد نتایج: 24316310  

this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this study examined the effect of prior knowledge and vocabulary teaching on iranian efl learners listening comprehension. the current study has two purposes: one is to investigate the effect of background knowledge on the second language listening comprehension of iranian intermediates and the other is to determine whether second language is facilitated by the introduction of unknown vocabularies in the form of prelistening activities. to conduct the study different instruments such as listening proficiency test and four listening tests such as pre and posttests were used and various statistical processes and techniques including paired-sample t-test, and analysis of variance (anova) were used. the findings of this study supported all three hypotheses tested. differences were found between the means of preteaching vocabulary variable, the background knowledge activation variable, and mean difference between these two strategies variable. subjects scored higher when the unknown words were taught in advance. likewise, subjects scored higher when they were asked some relevant questions about the topic than on those without them. there was, in addition, a significant difference between the means of preteaching vocabulary strategy and background knowledge activation strategy. in fact, preteaching vocabulary had a better effect in enhancing the students’ listening comprehension, in comparison to background knowledge activation strategy.

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده زبانهای خارجی 1390

this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this stud...

The chloride corrosion of reinforcing steel in reinforced concrete (RC) structures is a significant reason for premature deterioration and failure of RC structures in aggressive environments such as Persian Gulf region. This is one of the most important sources of engineering and economic problems in developed countries. So, the repair and maintenance of RC structures exposed to corrosive envir...

Journal: :international journal of iron & steel society of iran 2012
m. alishahi s. m. monirvaghefi a. saatchi

in the present study, ni-p-cnt composite coating was successfully fabricated via electroless plating. scanning electron microscopy (sem) was used to characterize the coatings. the effect of cnts concentration in the bath on its content in the composite coatings was studied. furthermore, the corrosion behaviour of the coatings with different contents of cnts was evaluated using tafel polarizatio...

ژورنال: مهندسی دریا 2015

In this study, Plasma Electrolytic Oxidation (PEO) technique was used for generating ceramic layer on the surface of aluminum alloy AA2024-T6 and the effect of coating time on the electrochemical corrosion behavior, micro-hardness, morphology of coating, and the phase structure was studied. The alloy was coated in 1, 3, 5 and 7 minutes at a constant electrical potential 550 V in a sodium silica...

رئیسی, کیوان, رجائی, وحید, رشتچی, حامد, شمعانیان, مرتضی,

In this study, Ni-Mo nanocrystalline alloys were prepared on steel substrates by electrodeposition method from citrate-ammonia bath by applying current densities 30, 60 and 100 mA/cm2. Results indicated that the obtained coatings were uniform and compact. Moreover, molybdenum content in the alloy and current efficiency decreased with increasing electrodeposition current density. X-ray diff...

Journal: :physical chemistry and electrochemistry 0
ramineh medhat department of materials science and engineering, shiraz university, shiraz, iran mahmoud pakshir department of materials science and engineering, shiraz university, shiraz, iran khashayar morshed behbahani department of materials science and engineering, shiraz university, shiraz, iran pooria najafisayar department of materials science and engineering, shiraz university, shiraz, iran

in this study, the effects of forming method (extrusion) and environmental factors (solution ph and temperature) on the corrosion performance of az91 magnesium alloys were investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (eis), scanning electron microscopy (sem) and salt spray techniques. the polarization test results of the specimens showed that simple sh...

Nickel films of 300 nm thickness were deposited by electron beam evaporation at room temperature on 316 stainless steels. Corrosion studies of Ni coated 316 SS have been performed after N+ ion implantation at different energies of 20, 40, 60 and 80 keV. The structure and surface morphology of the films were evaluated using X-ray diffraction (XRD), atomic force microscope (AFM) an...

Journal: :the modares journal of electrical engineering 2010
reza - shoja razavi taghi shahrabi reza mozafarinia

chromate conversion coating is applied on aluminum 6061. the optimum conditions for chromate bath composition and immersion time are also obtained for standard requirements provision such as corrosion resistance in salt spray test, electrical resistance and coating quality. the applied coatings are electrochemically tested in sea and distilled water. according to tafel and cyclic polarization c...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه - پژوهشکده ادبیات 1393

testing plays a vital role in any language teaching program. it allows teachers and stakeholders, including program administrators, parents, admissions officers and prospective employers to be assured that the learners are progressing according to an accepted standard (douglas, 2010). the problems currently facing language testers have both practical and theoretical implications but the first i...

A. Shafyei, M. Golozar S. Shahabi

A series of TiAlON coatings were synthesized in a gaseous mixture of argon, nitrogen and oxygen by cathodic arc evaporation method using a Ti–Al mosaic target. Oxidation of coatings was carried out by heating the coated samples at the temperatures of 500, 600, 700, and 800°C for 1 h in air atmosphere. It was found that heat treatment changed the microstructure and composition of the coating. Th...

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