| 摘要 |
Hydraulically setting refractory concrete is used to make wear-resisting parts which come into contact with molten metals. The concrete has a high alumina content, and the dried green product has a cold compression strength (CCS) of >=400 kp/cm2 which, after sintering at 1400 degrees C attains a CCS of >=700 kp/cm2 with a dimensional stability at 1400 degrees C better than plus-or-minus 0.2%. The pref. concrete contains corundum and active alumina, plus an alumina cement contg. less than 22% CaO, and possible a liquefier, the resulting analysis being 96% min. Al2O3, 3% max. CaO and 0.5% max. SiO2. Up to 5% of the alumina additions can be replaced by a substance forming a spinel, pref. MgO, or by soot, pitch or graphite; and >=7% chromium oxide may be included. Used to make stopper plugs or bushes, and esp. the moving or stationary plates in sliding stoppers used on vessels holding molten steel, where the molten jet of steel is up to 120 mm dia. |
