ZIRCONIA-GRAPHITE REFRACTORY EXCELLENT IN CORROSION RESISTANCE AND NOZZLE FOR CONTINUOUS CASTING USING THE SAME

摘要

PROBLEM TO BE SOLVED: To improve the corrosion resistance of a refractory by incorporating a specified zirconia material and graphite. ;SOLUTION: The objective zirconia-graphite refractories are obtd. by blending 70-90 wt.% zirconia material contg. ≥70% zirconia particles of ≤45 μm particle diameter with 5-30 wt.% graphite such as flake graphite, electrode scrap, anthracite or earthy graphite. An antioxidant such as ZrB₂, SiC, CaB₆ or B₄C, an additive such as metallic Si, Al, Mg or Zr and a binder are added to the zirconia-graphite refractories. They are molded in a nozzle shape and fired under reduction to obtain the objective nozzle for continuous casting using the zirconia-graphite refractories in at least a part of the immersion nozzle brought into contact with slag. Fine powdery zirconia is destabilized and dispersed in slag as fine particles, the concn. of a solid phase in the slag is increased by the dispersed destabilized zirconia and the apparent viscosity of the slag is increased, accordingly the infiltration of the slag into the refractories can be inhibited.;COPYRIGHT: (C)1999,JPO