Wetting and Erosion of ZrO2-Graphite Refractory by CaO-SiO2 and CaO-Al2O3-Based Mold Slags for Submerged Entry Nozzle

Abstract

To moderate the erosion in a slag-line zone and extend the service life of a submerged entry nozzle during continuous casting of high-Mn and high-Al steel, the current study developed a low-reaction CaO-Al2O3-based slag with lower SiO2 and higher Al2O3 contents than that of conventional CaO-SiO2-based slag. The static sessile drop technique and dynamic rotating cylinder method were utilized to investigate the erosion behavior of ZrO2-graphite refractory by the above slags. The main results indicated that silicate-based slag could wet the ZrO2-graphite substrate completely, while the aluminate-based slag spread rapidly in the first 20 minutes, and then a slag drop with an unchanged profile formed on the substrate. The equilibrium contact angles with the substrate at 1623 K were 0 and 79 deg for the CaO-SiO2 and CaO-Al2O3 based slags, respectively. The comparison of the influences of the rotating speed and the temperature revealed that the decrease of erosion rate could be realized by the developed slag. An examination of ZrO2-saturation limit also indicated that the low-reaction slag could dissolve much more ZrO2 oxidation, accompanied by a less-negative effect on the viscosity of the molten slag.