DOI: 10.21276/sjet

Pages: 280-289

Alumina-graphite (Al2O3-C) refractories are used as immersion nozzles for the continuous casting of steel. Carbon containing refractory materials have been widely used due to their excellent mechanical properties, thermal shock resistance and corrosion resistance. The life of these nozzles are limited by the localized corrosion, which occurs at the melt mold flux-metal interface. These refractory pieces are constituted by a body of alumina-graphite (Al2O3-C) with an insert of zirconia-graphite (ZrO2-C). The insert is placed in the bottom of the nozzle to protect the vulnerable zone from chemical attack. For this reason, the deep understanding of the mold fluxes effect on the wear mechanisms of the nozzles is relevant in order to avoid premature damage and contribute to decrease the cost of black refractories in the industry. In this paper, the nozzle selected for the study was characterized considering the chemical composition determination (integrating different instrumental techniques), the thermal behaviour (obtained by thermal analysis DTA/TGA), physical properties (such as density and apparent porosity) and microstructural characteristics (carried out by optical microscopy).