Transformation kinetics of theta- to alpha-phase of alumina powders prepared from different alumina salts by chemical processing
| Autor: | H. Özkan Toplan, Nil Toplan, Mediha Ipek |
|---|---|
| Přispěvatelé: | Ipek, M, Toplan, N, Toplan, HO, Sakarya Üniversitesi/Mühendislik Fakültesi/Metalurji Ve Malzeme Mühendisliği Bölümü, İpek, Mediha, Toplan, Nil, Toplan, Hüseyin Özkan |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
chemistry.chemical_classification
Materials science Precipitation (chemistry) Scanning electron microscope Salt (chemistry) chemistry.chemical_element 02 engineering and technology Activation energy 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 010406 physical chemistry 0104 chemical sciences law.invention Crystallography Chemistry chemistry Aluminium law Crystallite Physical and Theoretical Chemistry Crystallization 0210 nano-technology Scherrer equation Nuclear chemistry |
| Popis: | The aim of this study was to produce nanosized alumina powders from two different aluminum salts (AlCl3 and AlNO3.9H(2)O) by precipitation method and to investigate transformation kinetics of alpha-Al2O3 crystallization obtained from quantitative DTA curves via Kissinger-Akahira-Sunose (KAS) method. Precipitates are dried at 80 A degrees C for 24 h and then calcinated at 1200 and 1300 A degrees C for 1 h. Dried powders have bayerite [Al(OH)(3)] and calcinated powders have theta- (theta) and alpha (alpha)-alumina phases which confirmed by XRD analysis, and the crystallite size of powders determined by Scherrer equation is about 30 nm for dried powders and ranged from approximately 15-35 nm for calcinated powders. Scanning electron microscopy studies revealed that the morphology and size of powders precipitated from two different salts are similar to each other, and powders contain mainly sub-micrometer-sized particles and close to spherical form. Activation energy values determined by KAS equation range from 717 to 411 kJ mol(-1) for powders produced from aluminum nitrate salt and from 844 to 476 kJ mol(-1) for powders produced from aluminum chloride salt depending on the transformation rate. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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