پديد آورنده :
ابراهيمي كهريزسنگي، رضا
عنوان :
بررسي سينتيك اكسيداسيون موليبدنيت در شرايط غير هم دما و اثرات فعال سازي مكانيكي برآن
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد
صفحه شمار :
چهارده، 153، [II]ص.: مصور، جدول، نمودار
يادداشت :
ص. ع. به فارسي و انگليسي
استاد راهنما :
محمدحسن عباسي
توصيفگر ها :
مكانوشيمي , آسياب هاي لرزشي، گلوله اي، سايشي , دستگاه ِDSC،STA ، XRD, , دستگاه ICP ،BET
استاد داور :
خطيب الاسلام صدرنژاد، بيژن نجفي، اسكندر كشاورز، علي شفيعي
تاريخ ورود اطلاعات :
1396/02/24
كد ايرانداك :
ID157 دكتري
چكيده فارسي :
به فارسي و انگليسي: قابل رويت در نسخه ديجيتال
چكيده انگليسي :
AbstractThe effects of mechanical activation on the kinetics of Molybdenite oxidation under non isothermal conditions were studied with model fitting Coats Redfern and model free Ozawa Fridman Kessinger methods For this purpose TG DTA DSC BET and XRDexperiments were used Mechanical activation was carried out in a planetary ball millunder air atmosphere with ball to powder weight ratio of 20 and milling speed of 800 rpm The changes of specific adsorption surface area lattice strain stored energy and percentof crystalline phase were investigated The results showed that at the early stages ofmilling dominant phenomena was the increase in specific adsorption surface area and atthe final stages the increase in lattice strain and amorphous phase formation The TG andDTA experiments were carried out under non isothermal conditions with the linear heatingrates of 5 10 15 and 20 min and oxygen with 50ml min flow was used as the purge gas The study of Molybdenite non isothermal oxidation kinetic by Coats Redfern CR methodshowed that the CR method could not be a reliable method to determine the kineticparameters if used alone So the data obtained using CR method were evaluated by othermethods The results showed that the oxidation of non activated Molybdenite has achemical controlled mechanism with 34 25 kcal mol activation energy and 2 108 Sec 1pre exponential factor It was also showed that by increasing the extent of reaction theshape of particles changes due to crystallization of the oxidation products However thereaction mechanism does not change By milling the Molybdenite for 5 hours the ignitiontemperature of reaction decreased from 470 C to 308 C and the reaction mechanismchanged to diffusion controlled with 60 55 kcal mol activation energy and 6 1019 Sec 1pre exponential factor at the reaction extents less than 0 6 The reaction mechanismchanged to chemical controlled mechanism at the reaction extents greater than 0 6 bycracking and crystallization of the oxide layer Also the increase in the milling time causesfurther decrease in the ignition temperature but does not change the reaction mechanism Minor changes were observed in the activation energy and mechanical activation mainlyaffected the reaction kinetics by changing the pre exponential factor The kinetic analysisof Molybdenite oxidation using model free methods showed good agreement with CRresults Oxidation of Molybdenite via parallel reactions was also studied using model freemethods
استاد راهنما :
محمدحسن عباسي
استاد داور :
خطيب الاسلام صدرنژاد، بيژن نجفي، اسكندر كشاورز، علي شفيعي
