"Considerable research has been conducted in the past 30 years to improve the hydration resistance of magnesia-based refractories. The addition of boron to magnesite, brucite, and to light-calcined or post dead-burned magnesia has been found to be effective in increasing hydration resistance. However, the presence of boron tends to decrease the hot load-bearing properties of the magnesia and may adversely affect certain grades of steel. One of the objectives of the present study was to investigate the effect of various oxide additions on the hydration susceptibility of magnesia.
This study involved the determination of the lattice energies for MgO with a variety of substitutions being made for Mg including Li, Na, Ca, Ni, Fe, Co, Al, B, Cr, Fe, Ti and Mn using the computer program WMIN. Since the distribution of the dopant atoms in the structure affects the lattice energy, a program was written to systematically generate all possible distributions of the dopant atoms in a supercell consisting of a 2x2x2 array of MgO unit cells. Examination of the lattice energies calculated using the different configurations indicated energies differing by several tens of Kcals and rather interesting frequency distributions among the energies. In addition, there appears to be trends with respect to the ordering and clustering of the dopant atoms.
The results of our study agree with the trends reported in the literature regarding the effect of CaO, Fe2O3, TiO2, and B2O3 additions on the hydration susceptibility of MgO. The addition of CaO reduces the lattice energy by approximately 2 Kcal/mole whereas B2O3 increases it by approximately 20 Kcal/mole. Fe-doped MgO has nearly the same lattice energy as undoped MgO. Although a number of factors contribute to the physical properties of MgO, our preliminary results indicate that our lattice energy calculations appear to have enough potential to warrant further study"--Abstract, pages ii-iii.
Howard, Scott A.
Moore, Robert E., 1930-2003
Leighly, Hollis P., 1923-2004
Materials Science and Engineering
M.S. in Ceramic Engineering
University of Missouri--Rolla
viii, 47 pages
© 1989 Soon Ho Lee, 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=b2173498~S5
Lee, Soon Ho, "Investigation of hydration susceptibility of MgO doped with oxides in terms of lattice energy" (1989). Masters Theses. 761.