Authors:
Dr. Wei Lin | Shinagawa Refractories Co., Ltd. | Japan
Dr. Wei Lin | Shinagawa Refractories Co., Ltd. | Japan
Takayuki Matsunaga | Shinagawa Refractories Co., Ltd. | Japan
Toshio Horiuchi | Shinagawa Refractories Co., Ltd. | Japan
For many years, CaO-ZrO2-C (CZ-C) have been used for the submerged entry nozzles (SENs) as the inner lining material to prevent the alumina deposition. In some cases, however, extraordinarily large wear rates were recognized. In the vicinity of working surface of post-used SEN that had shown rapid wear, deteriorated layer with considerable amount of ZrC was observed. Therefore, it is presumed that abrasion of deteriorated layer, which was occurred by ZrC formation reaction, by steel flow took place. According to the presumption, influences of Al2O3 and/or MgO addition to CZ-C material on the ZrC formation reaction and on the alumina deposition resistance were investigated.
As a result of the laboratory experiment of which specimens were heated in argon atmosphere, significant reduction in ZrC formation was observed for the specimens containing 5 mass% of spinel or Al2O3. EPMA analysis revealed that; while the conventional CZ-C showed porous structure with isolated grains, Al2O3 or MgO-added specimens showed dense microstructure with formation of low melting point phases of Al2O3-CaO system, which coated CZ, ZrO2 and ZrC grains. Furthermore, it was confirmed that Al2O3 or MgO-added specimens exhibits equivalent alumina deposition resistance to conventional CZ-C by molten Al-killed steel-dipping experiment.