Priprava Al2O3 sintezom sagorijevanjem

undergraduate thesis

• Title (english): Combustion synthesis of alumina
• Author: Emina Ema Alić
• Mentor: Stanislav Kurajica (mentor)
• Committee member: Stanislav Kurajica (predsjednik povjerenstva)
• Committee member: Vilko Mandić (član povjerenstva)
• Committee member: Krunoslav Žižek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2018-09-03, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Basic Technical Sciences; Materials

Abstract

Istraživani su procesi do kojih dolazi tijekom kristalizacije prašaka pripravljenih sintezom sagorijevanjem. Kao prekursori pri sintezi sagorijevanjem korišteni su aluminijev nitrat nonahidrat kao oksidans i alanin kao gorivo. Provedene su sinteze sa različitim omjerima goriva i oksidansa (siromašne gorivom, stehiometrijska i bogate gorivom). Prašci pripravljeni sintezom sagorijevanjem istraživani su diferencijalnom toplinskom i termogravimetrijskom analizom (DTA/TGA), pretražnom elektronskom mikroskopijom (SEM), rendgenskom difrakcijom (XRD) i infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR). Opisan je utjecaj omjera goriva i oksidansa na sastav prašaka i promjene uzrokovane toplinskom obradom. Utvrđeno je da vrijeme zapaljenja, brzina gorenja i postignuta temperatura tijekom reakcije sagorijevanja ovise o udjelu nitrata i alanina. Uzorak s najvećim udjelom goriva zapali se u najkraćem vremenu, gori najbrže i postiže najviše temperature. Međutim, reakcija je najpotpunija, odnosno zaostaje najmanje organske faze tijekom sinteze uzorka s više oksidansa. Amorfni prah kristalizira u γ-Al2O3 na temperaturi oko 800 ⁰C, dok spora transformacija u α- Al2O3 započinje na temperaturi oko 1000 ⁰C. Neovisno o omjeru goriva i oksidansa, toplinskom obradom na 800 ⁰C tijekom dva sata uspješno je dobiven porozni γ- Al2O3. Toplinskom obradom na 1000 ⁰C u trajanju od dva sata postignuta je potpuna transformacija γ- Al2O3 u α- Al2O3.

Abstract (english)

The processes in the course of crystallization of powders prepared by solution combustion synthesis have been investigated. Solution combustion synthesis has been accomplished using aluminum nitrate nonahydrate as oxidizer and alanine as a fuel. In the course of synthesis samples with various ratios of alanine to nitrate (fuel-lean, stoichiometric, and fuel-rich) have been used. Differential thermal and thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used for investigation of powders obtained by solution combustion synthesis. Influence of fuel to oxidizer ratio on composition and thermal evolution of powders prepared by synthesis have been described. It was shown that combustion reaction ignition time, combustion rate and achieved temperature depends upon the nitrate to alanine ratio. The sample with the most fuel ignites first, burns fastest and reaches greatest temperature. However, it was established that combustion reaction was more complete, leaving less organic residue, in sample with the most oxidizer. It has been shown that amorphous powder crystallizes to γ-alumina around 800 °C, while its slow transformation to α-alumina commences around 1000 °C. Regardless of fuel to oxidizer ratio, thermal treatment at 800 for two hours was sufficient to prepare porous γ-alumina. Thermal treatment at 1000 °C for two hours yields with complete transformation of γ- to α-alumina.

• Keywords: aluminijev oksid; kristalizacija; sinteza sagorijevanjem
• Keywords (english): alumina; crystallization; combustion synthesis
• Language: croatian
• URN:NBN: urn:nbn:hr:149:821034
• Study programme: Title: Materials Science and Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-06-23 12:56:49