| 摘要 |
PURPOSE:To extend the service life of a nozzle by blending a graphite of specified wt.% with the oxide refractory raw material composing a nozzle and blending the nonoxide refractory material having specified proper resistance as occasions demand at specified rate. CONSTITUTION:A dipping nozzle 1 is provided between a tundish 2 and mold 3, a pair of the electrodes 5 for heating with electrification are arranged on the peripheral face of the nozzle 1 as well and a heating current is fed from a power source 6. In this case, 5-20% graphite is blended with the oxide refractory raw material of an alumina, etc., composing the nozzle 1. If necessary the nonoxide refractory raw material whose proper resistance is <=1X10<-4>OMEGAcm is added by blending at the rate of 2-20%. Due to the graphite contg. amt. being regulated lower the corrosion resistance and thermal impact resistance of the nozzle 1 are improved. The heat dissipation is reduced and base metal deposition is prevented because the electric conductivity is improved by the blending of non-oxide refractory raw material. Consequently the nozzle life is extended. |
