Influence of Mould Slag Compositions with Different Reactivity on the Erosion Rate of ZrO_2-C Bearing Submergence Entry Nozzle

摘要

Several slag compositions of differing reactivity were designed as a potential measure for reducing erosion on submergence entry nozzle during continuous casting of high-Mn high-Al steel. Reactivities were determined according to the SiO_2 content of the slag considering the reaction between [Al] and (SiO_2) at the steel-slag interface. The erosion rate was evaluated by means of the rotating cylinder method; a ZrO_2-C rod was immersed in the 1673 K slag sample for two hours, and the erosion rate was evaluated according to the reduction of rod diameter. The effect of slag components Na_2O, Li_2O, CaF_2 and B_2O_3 on the erosion rate was investigated. The main results indicate that slag with low SiO_2 content was more effective in decreasing the erosion rate than conventional high-SiO_2 slag. Listed in decreasing order of intensity, the effects of the individual components on the erosion rate are Na_2O, CaF_2, Li_2O and B_2O_3. The ultimate aim of the mould slag optimization effort is stabilizing the operation by extending the submergence entry nozzle service life.