"Spinel-forming refractories reduce penetration by tightening the bulk of the lining due to the volume expansion resulting from spinel formation. However, excessive volume expansion can result in cracking, penetration of the hot face, and spalling. Sintered spinel, with a lower thermal expansion than alumina and magnesia, is added to reduce the cracking associated with the volume increase from spinel transformation.
Tests were carried out to evaluate the differences between the performance in spinel-forming and spinel-containing refractory mixes. Eight refractory linings, one pure magnesia, three magnesia-based spinel-forming and four alumina-based spinel-containing dry vibratable mixes, were tested by melting and holding a low-carbon, low-manganese steel in an induction furnace lined with each mix for four hours at 1600°C. After tapping the steel, lining samples were cut and measured for wear and penetration.
For the magnesia-based mixes, an optimum amount of spinel was found to form around 28wt.%. This mix minimized the wear at both the sidewalls and slag line. Further experiments are required to determine the exact composition for optimization.
For the alumina-based mixes with spinel additions, there seems to be an optimum ratio of spinel added to spinel formed resulting in a minimum of penetration and wear at the slag line. However, accretions formed at the sidewalls which were thickest for the mix with the ratio of spinel formed to spinel added near the optimum. Therefore, to design an optimum refractory mix, the benefits of higher ratios of spinel added to spinel formed to reduce penetration and wear at the slag line will need to be balanced with the tendency to form accretions at the sidewalls"--Abstract, page iii.
Peaslee, Kent D., 1956-2013
Smith, Jeffrey D.
Miller, F. Scott, 1956-
Materials Science and Engineering
M.S. in Metallurgical Engineering
Peaslee Steel Manufacturing Research Center
University of Missouri--Rolla
xi, 85 pages
© 2003 José María Soto Perdomo, All rights reserved.
Thesis - Restricted Access
Refractory materials -- Testing
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Soto Perdomo, José María, "Evaluation of spinel refractory interactions with steel in coreless induction furnaces" (2003). Masters Theses. 2421.
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