فهرس المقالات activation energy

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  1 - Evaluation of Flow Behavior of Novel Titanium Ti-3873 Alloy Via Compressive Deformation in Two Phase α/β and Single Phase β Regions
  Mahnaz Dabbaghi Maryam Morakabati
  Semi-stable β-titanium (Ti-3873) Ti-3Al-8Mo-7V-3Cr alloy with excellent workability properties has been designed based on high demanded aircraft Ti-5Al-5Mo-5V-3Cr alloy according to semi-experimental d-electron approach. The aim of the present research is to investigate أکثر

  Semi-stable β-titanium (Ti-3873) Ti-3Al-8Mo-7V-3Cr alloy with excellent workability properties has been designed based on high demanded aircraft Ti-5Al-5Mo-5V-3Cr alloy according to semi-experimental d-electron approach. The aim of the present research is to investigate the deformation behavior of Ti-3873 alloy via warm compression test. For this purpose, compression test has been conducted in the temperature range of 650-850 °C and strain rates of 0.001,0.1 and 1, 1 s-1 at dual phase α/β and single phase β regions. The test was continued up to plastic strain of 0.7. For establishing the relationship between the microstructure and flow behavior, the initial and subsequent microstructure of the specimens after warm deformation was studied via optical and scanning electron microscopes. The microstructural evaluation and flow curves revealed that dynamic recovery and partial continuous dynamic recrystallization were the dominant restoration mechanisms. The results showed that softening has been increased in the temperature range of 800-850 °C and strain of 0.001 and 0.1 s-1 which is confirmed by the activation energy calculated from the sinus hyperbolic equation. The activation energy for dual phase α/β and single phase β regions are determines as 429 kJ/mol and 353 kJ/mol, respectively. The higher value of activation energy for α/β dual phase region is attributed to dynamic globularization of α lamellas. The preferable regions for hot workability of the alloy were achieved at the temperature range of 800-850 °C and strain rate of 0.01-0.001 s-1 corresponding to the peak efficiency of 39% in the processing map. تفاصيل المقالة
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  2 - Kinetics study of biodiesel synthesis from sunflower oil using Ba-Sr/ZSM-5 nanocatalyst
  Mostafa Feyzi Gelareh Khajavi
  In the present research work, the kinetics of sunflower oil transesterification reaction in the presence of Ba-Sr/ZSM-5 nanocatalyst which prepared using incipient wetness impregnation method was investigated. The 10wt.%Ba-Sr/ZSM-5 (Sr/Ba=3/2) nanocatalyst was calcined أکثر

  In the present research work, the kinetics of sunflower oil transesterification reaction in the presence of Ba-Sr/ZSM-5 nanocatalyst which prepared using incipient wetness impregnation method was investigated. The 10wt.%Ba-Sr/ZSM-5 (Sr/Ba=3/2) nanocatalyst was calcined at 600 °C for 6 h with a heating rate of 3 ºC/min. The experimental conditions were the methanol/oil 9/1molar ratio, reaction time (0-180 min) and reaction temperature (323–333 K) with mechanical stirring of 500 rpm. An irreversible pseudo-second order kinetics was considered for triglyceride conversion from the best modeling of experimental data. From the kinetic study, Ea=67.03 kJ/mol and A=9.29×108 1/min were obtained. The yield of the methyl ester products (86.69%) were determined using gas chromatography–mass spectrometry. characterization of the catalysts and precursors was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-Ray diffraction (XRD), Transmission electron microscopy (TEM), and N2 adsorption-desorption measurement methods. تفاصيل المقالة