Preparation And Application Of New-style Sealing Member For Continuous Casting Nozzle

Molten steel is purified after shielding practice applied in continuous casting process and the slab quality is therefore improved. In addition, nozzle clogging and mold surface scull are also reduced. The primary purpose of shielding practice is to avoid or reduce the contact of steel flow and air. As a result, in order to achieve shielding casting, long nozzle is usually used between the ladle and tundish.During casting, the upper end of long nozzle is connected with lower nozzle while its lower end inserted into molten steel in tundish. Because of the high speed steel flow when molten steel flow from ladle to tudish through long nozzle, a negative pressure is formed near its upper end. Thus, air is absorbed into steel and the quality of slab is worsened. It is therefore necessary to design some certain kind sealing member which could seal up the joint of nozzles and accomplish an optimal effect of shielding casting.In this study, a new-style sealing member for continuous casting nozzle was prepared by using corundum and black pigment as major starting materials, by using plasticizer, antioxidant and heat intensifier as auxiliary materials and phenolic resin as binder. The sealing member could gradually generate tiny expansion with a property of low hardening ratio at high temperature. Effects on properties of the member, such as apparent porosity, bulk density, cold deformation ratio, high-temperature hardening time, etc., were studied by adding different components and contents of binder. Effect on oxidation resistance of the member was also investigated by changing the proportion of starting materials. Furthermore, the prepared new-style sealing member was practical used in steel plant and a satisfied consequence was acquired.The following conclusions were obtained according to the experiments and studies.(1) Both component and content of binder influenced physical and chemical properties of the new-style sealing member material greatly. (2) Cold deformation ratio of the new-style sealing member was stayed by adding reagent a in the binder. A longest high-temperature hardening time was gained by adding binder with a proportion of 80% phenolic resin and 20% reagent a.(3) It was confirmed that the sealing member has a good oxidation resistance property. But increasing the addition of antioxidant on the current proportion hardly influenced its oxidation resistance.(4) Nitrogen recruitment of steel was markedly reduced during continuous casting when using the new-style sealing member because of its excellent airtightness.(5) The sealing member was easily to be installed and dismantled. What is more, it was also easily to be saved and its plasticity could be retained for a long time.