Formation Process of Alumina by Thermal Decomposition of Aluminum Sulfate

Autor:	Eiichi Ishii, Takeo Iga, Shiro Sano, Shuzo Kato
Rok vydání:	1969
Předmět:	Materials science Thermal decomposition Metallurgy chemistry.chemical_element equipment and supplies chemistry.chemical_compound Grain growth chemistry Electron diffraction Chemical engineering Aluminium Particle Water of crystallization Sulfate Thin film
Zdroj:	Journal of the Ceramic Association, Japan. 77:60-65
ISSN:	1884-2127 0009-0255
DOI:	10.2109/jcersj1950.77.882_60
Popis:	Thermal decomposition of aluminum sulfate into α-alumina was investigated by D. T. A., T. G. A., X-ray analysis and electron microscopic observation.The results obtained were as follow:Aluminum sulfate melted in its own water of crystallization when heated, and high viscous solution was obtained. This solution evaporated vigorously above 100°C. Bubble formation was observed because of difficulty in releasing water vapor due to high viscosity of the solution. Then the skeleton particles composed of the network of thin film layers were formed. They were decomposed to r-alumina keeping this shape. The r-alumina consisted of very fine particles. A remarkable grain growth was observed together with transition to α-form. The transition initiated from a part of a skeleton particle with a rapid rate. From this fact, the rate controlling process may be the nucleation.It was confirmed by the electron diffraction that the inside of the skeleton particle showed a high orientation because the transition and grain growth proceeded from one or a few nuclei.
Databáze:	OpenAIRE
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