| 摘要 |
PURPOSE:To obtain an air-permeable refractory excellent in air-permeation characteristics, physical characteristics, melted steel erosion resistance and spalling resistance by employing both natural graphite and artificial graphite as graphite and further using both alpha-type alumina and beta-type alumina as alumina. CONSTITUTION:10-40wt.% of a graphite mixture comprising 20-90% of natural graphite and 10-80% of artificial graphite is compounded with 50-90wt.% of an alumina mixture comprising 20-80% of alpha-type alumina and 80-20wt.% of beta-type alumina. Si or SiO2 is not contained in the alpha-type and beta-type aluminas except the ash of the graphite and the glass component as an inevitable impurity. SiC may partially by added for the improvement of oxidation resistance. The compounded product is incorporated with a phenolic resin, a mixed and kneaded, and the obtained raw material mixture is molded and reductively fired at 1000-1200 deg.C. The produced air-permeable refractory is used to improve the quality of a slit type immersion nozzle on the continuous casting of aluminum-killed steel, etc. |
