The gas-permeability tests of alumina-graphite casting nozzles and the studies of deposit samples and nonmetallic inclusions in the samples taken from a tundish allow the following conclusions: The low pressure in casting channels and the high gas permeability of alumina-graphite uncoated nozzles indicate that air can reach the metal-stream sur face even when argon is blown through the tundish noz zle-submerged entry shroud joint. The revealed differences (in composition and shape) between the deposit crystals and the nonmetallic inclusions in the samples taken from the tundish sup port the assumption that metal-stream oxidation in non-swirl and submerged entry shrouds is one of the main potential sources of deposit formation. These results were used to develop measures to decrease the reoxidation of the metal stream and to compensate for the negative effect of reoxidation.
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