One approach to solving the problem of nozzle clogging during the continuous casting of aluminum-killed steels is through careful selection of nozzle materials. In this study, the rate of clogging was measured while casting steel through simulated nozzles produced from alumina, zirconia, magnesia, zirconia-graphite, and alumina-graphite -three common base materials and two common carbon-containing nozzle materials. Spent nozzles were characterized using optical and cathodoluminescence microscopy. Interactions between the nozzles and steel were not observed in the alumina, zirconia, and zirconia-graphite nozzles. Slight interactions were observed in the magnesia nozzles as alumina inclusions within the steel interacted with the nozzle to produce alumina-magnesia spinel. Greater amounts of interaction were observed with alumina-graphite nozzles. No statistical differences in the mean rate of clogging were observed between all of the pure oxide nozzles and Zirconia-graphite nozzles. However, the alumina-graphite nozzles clogged at a much higher rate than the other nozzles. The higher rate of clogging is thought to be due to refractory-steel interactions.
The results of an experimental program assessing the potential of several chrome‐free refractory materials as potential replacements for the mag‐chrome brick currently used in copper production furnaces are presented. Several commercial chrome‐free bricks were subjected to the standard dip test in a high‐copper calcium ferrite slag. The mineralogical changes in the bricks resulting from their interaction with the molten slag are described. The use of optical cathodoluminescence microscopy as an analytical tool is highlighted, along with reflected light microscopy and scanning electron microscopy–energy dispersive spectroscopy. Using the three tools together provides a description of the experimental results not achievable using one or two alone. The penetration resistance of the potential replacement refractories is comparable to that of mag‐chrome, but the substitution of Fe2+ for Mg2+ in the periclase and spinel crystalline structures of the replacements reduces their corrosion resistance compared with mag‐chrome, diminishing the likelihood that they will serve as reliable alternatives.
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