"Alumina-magnesia spinel is being used increasingly as a high quality refractory material in furnace and cement rotary kiln applications, but the cost of synthetic powders and grains limits its application. Different sources of bauxite from Guyana and China, and diaspore from Missouri have been utilized to synthesize spinel for refractories in order to reduce the cost.
The purpose of this research is to examine the extent and character of spinel formation under different firing conditions and varying Al₂O₃:MgO ratios. Finely ground aluminous raw materials were mixed with hardburned magnesia in certain ratios to form spinel. X-ray analysis was used for mineralogical analysis and showed that after heating at 1550°C, spinel readily occurs together with some impurity minerals such as rutile, corundum, mullite, aluminum titanium oxide and some glassy phase.
Reflected light microscopy, scanning electron microscopy (SEM) and cathodoluminescence microscopy (CLM) were utilized in a microstructural study to determine the amount and distribution of each phase present in thirty-nine samples prepared at different firing temperatures and with different starting chemical compositions. The chemical compositions of each phase were also analyzed by an energy dispersive X-ray spectrometer (EDS).
The results of this investigation provide a better understanding of the nature of the microstructure of synthetic spinels and indicate that selection of starting raw materials is crucial in the synthesis, among all the variables which could affect the nature and the amount of phases generated"--Abstract, pages iii-iv.
Hagni, Richard D.
Moore, Robert E., 1930-2003
Grant, S. Kerry
Geosciences and Geological and Petroleum Engineering
M.S. in Geology and Geophysics
University of Missouri--Rolla
xii, 47 pages
© 1993 Yu-I Eunice Chao, All rights reserved.
Thesis - Restricted Access
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Link to Catalog RecordElectronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library. http://laurel.lso.missouri.edu/record=b2437715~S5
Chao, Yu-I Eunice, "Microstructural study of synthetic alumina-magnesia spinel for refractories from natural raw materials" (1993). Masters Theses. 1182.