Effects Of Additives On Properties Of Al₂O₃-ZrO₂-C Submerged Entry Nozzle

At present people are facing with serious energy, environment and development issues. Continuous casting mold to replace mold casting is a huge technological revolution of iron and steel industry. With significantly lower energy consumption, and a number of new secondary refining techniques, continuous casting mold greatly improve the productivity and product quality. Compared to the traditional mode casting process, continuous casting mold has a great of advantages. After development in several decades,Europe, the United States, Japan and other countries have achieved full-continuous casting. Continuous casting ratio of the iron and steel enterprises in China has reached more than 90%. With the rapid development of continuous casting production technology, continuous casting refractories put new demands on. As a long time, the merits and demerits of continuous casting refractories constraints continuous casting technology. Submerged entry nozzle as the final function refractory material of continuous casting refractories, also as one of the most critical refractory material of the process of continuous casting, play an important role in the quality of steel and continuous casting production capacity. Therefore, the study and optimization of submerged entry nozzle is important to ensure continuous casting production.In this study, the physical properties of Al2O3-ZrO2-C materials with suitable amount of additives such as Si powder, Al powder, Mn powder, Si+Al, Si+Mn, Al++Mn, and Si+Al+Mn were examined. And microstructure and phase of used and un-used materials were also determined by XRD, SEM.The study indicates as follows: Pressure resisting strength of materials with different size distribution dried at 200℃for 20h was greater than 40MPa and pressure resisting strength of mateials heat-treated at 1400℃for 3h was greater than 30MPa, which could meet the needs of strength for composite moulding with Al2O3-ZrO2-C materials and machining submerged entry nozzle. When the ratio of particles is 6/4, the material has the best physical properties.Suitable amount of additives such as Si powder, Al powder, Mn powder is effective to increase pressure resisting strength and improve oxidation resistance of Al2O3-ZrO2-C materials.And the Mn additive has shown the best effect, not only in increaseing the pressure resisting strength of materials,but in improving remarkably the oxidation resistance and thermal shock resistance. The addition of composite additives such as Si+Al, Si+Mn, Al+Mn, and Si+Al+Mn in Al2O3-ZrO2-C materials can decrease the apparent porosity and increase volume density and the pressure resisting strength respectively. The sample added composite additives(Si2%+Al1%+Mn4%)has shown the best pressure resisting strength, oxidation resistance and thermal shock resistance.