Didier-Werke Ag

Franz Schellberg

Gunter Gelsdorf

Hermann Leupold

Parts subject to wear, which come into contact with metal melts, are formed with a hydraulically setting high-alumina refractory concrete having a compression strength when cold, measured on dried crude product, of at least 400 kp/cm.sup.2. The compression strength is at least 700 kp/cm.sup.2 after firing at 1400.degree. C. The refractory concrete has a dimensional stability at 1400.degree. C. of at least plus or minus 0.2%. The refractory concrete contains corundum and active alumina as aggregates, an alumina concrete containing less than 22% lime and, as required, a thinning agent. Up to 5% of the aggregates can be replaced by a spinel-forming substance preferably MgO or MgO-yielding compounds; or up to 5% of the aggregates can be replaced by carbon black, pitch or graphite; or up to 7% of the aggregates can be replaced by chromium oxide. Aggregates under 0.5 mm can be present in the refractory concrete as round grains. Preferably, the refractory concrete is used for slide-valve plates and/or base plates of slide-valve closure members on containers containing steel melts. The moulded parts can be impregnated with tar.

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Wiesbaden-Frauenstein, Germany

Franz Schellberg