| 摘要 |
PURPOSE:To provide an immersion nozzle for continuous casting which dislodges clogging materials from the inside wall of the nozzle and prevents clogging by combining boron nitride and silica. CONSTITUTION:An org. binder is added to a compd. consisting, by weight, of 10-55% boron nitride, 15-40% silica, 13-30% graphite and 20-50% alumina and the mixture is molded by a rubber press. After this stage, the mixture is reduced and calcined, whereby an immersion nozzle for continuous casting which can prevent closing is obtd. More specifically, in the nozzle near the working surface, carbon bonds are deteriorated by the free oxygen evaporating from silica and further the sintering between alumina aggregate materials is suppressed by boron nitride, whereby structure embrittling layers are formed. When the abrasion resistance of molten steel flow increases, stuck and deposited layers are dislodged with the structure embrittling layers formed in the nozzle as a boundary. |
