| 摘要 |
PURPOSE:To prolong an exchanging term of a nozzle by forming a zirconia layer and on the rear face thereof, an electric conductive material layer in contacting with each other on an inner wall of the nozzle which is brought into contact with molten steel. CONSTITUTION:Submerged nozzle body 1 is formed of sintered material having alumina quality and the surface which is brought into contact with molten steel is formed of the zirconia layer 2 and further on the rear of this layer, the electric conductive material layer 3 such as graphite powder, etc., is formed. At this time, the zirconia layer 2 is formed by mixing 10-50wt% partial stabilized zirconia powder and 90-10wt% zirconia powder and stabilizing agent, and heat-treated at 500-1,500 deg.C after sintering. In this way, <=70% of the layer 2 changes to crystallized structure. As the zirconia sintered layer as oxygen ion conductor carries oxygen in the molten steel therein electro-chemically, it prevents sticking of alumina, etc., on the inner surface of the nozzle. Thus, the exchanging term of the nozzle is extended. |
