| 摘要 |
PURPOSE:To improve heat shock resistance and erosion resistance to molten slag, etc., at the time of continuously casting a steel slab and to enable casting of the cast slab having no longitudinal crack, etc. CONSTITUTION:At least slag line part in this nozzle contains zirconia and flake graphite, has no biased grain size distribution of the zirconia and consists of refractory having structure, having the flake graphite between large diameter grains, and forms two or more layers of coating layer, in which m.p. is higher as lower the layer becomes, on the outside of the refractory. The heat shock given to the refractory, is relaxed with the two or more layers of the coating layer. Further, the oxidation of the graphite in the refractory during preheating and in a little while after dipping can be prevented. Further, the mixture of fall-out grains from the refractory into mold powder, which is not perfectly formed to slag, can be prevented. During casting, as the grains are closely packed and the large diameter grains are held by the flake graphite, the fall-out of the zirconia grains from the refractory is not developed and this nozzle exerts no influence on the characteristic of molten slag and the longitudinal crack, etc., in the cast slab is not induced. |
