Effects　of　Carbon　and　Silica　in　Submerged　Entry　Nozzle　on　Alumina　Buildup

Abstract

　The　effects　of　carbon　and　silica　contained　in　the　submerged　entry　nozzles （SEN） on　alumina　buildup　were　investigated． Both　were　shown　to　be　harmful　to　alumina　deposition．A　carbon－free　high-alumina　SEN　was　developed　and　successfully　used　in　actual　continous　casters．The　mechanism　of　excellent　alumina　buildup　resistance　are　disscussed　as　follows： 1）Preventiion　of　alumina　near　molten　steel ／ nozzle interface caused by the oxidation of alumina in steel by　CO　and　SiO　gas　which　evolves　from　reactions　in　silica　and　carbon　containing　nozzle　refractory　materiats． 2）Suppression　of　concentration　gradient　of　elements　such　as　Si　and　C　in　the　interface　layer　between　nozzle　and　molten　steel，which　can　become　a　driving　force　of　attraction　of　alumina　particles　dispersed　in　molten　steel．