This invention relates to packing materials having properties such as high erosion resisting-airtightness and excellent separation easiness.
The so-called continuous casting has made a striking progress as one of modern teeming processes in steel making in recent years. Cast refractories produced by the continuous casting are generally classified into (a) refractories for ladles which are adapted to hold a batch of molten steel for a long time and then transfer the molten steel into tundish nozzles and (b) refractories for tundish nozzles. As means for controlling the flow rate of molten steel which flows from a ladle into a tundish or from the tundish into a mould, the so-called sliding nozzle system has been increasingly employed in place of the so-called stopper system.
When the sliding nozzle system is employed in conjunction with a ladle, for example, mortar is usually employed at the joint between the nozzle seating block and the upper nozzle, at the joint between the upper nozzle and the upper plate and at the joint between the lower plate and the lower nozzle to connect the respectively adjacent components together. And when the lower nozzle and the long nozzle are connected together, a ceramic fiber sheet has to be employed at the joint between the two nozzles so that the nozzles are easily separated from each other when ladle exchange operation is performed. When the stopper system is employed in connection with a tundish, a ceramic fiber sheet is employed at the joint between the tundish nozzle and the submerged nozzle to connect the two components together. When the sliding nozzle system is employed in connection with the tundish, mortar is employed at the joint between the upper nozzle and the upper plate and at the joint between the lower plate and the middle nozzle to connect the respectively adjacent components together, respectively and a ceramic fiber sheet is usually employed at the joint between the middle nozzle and the submerged nozzle to connect the two components together. When bricks are jointed together so that the brick assembly functions as one system, the packing material placed between the bricks performs a very important role.
Mortar has the inherent disadvantages that mortaring requires skilled hand, that the mortar cannot be removed from the joints of bricks without doing damage to the joints of bricks and the mortar has insufficient airtightness. Although ceramic fiber also has the inherent disadvantages that the ceramic fiber is easily attacked by molten steel, that the ceramic fiber has insufficient airtightness and that the ceramic fiber imperatively necessitates brick exchange in a brief time, the ceramic fiber is widely employed because the material can be easily and rapidly separated from the joints between bricks.