Abstract: A stopper rod for controlling the flow of molten steel from a tundish has a metal carrier element partly received in an internal passageway of the stopper rod, the carrier element compressing sealing means between a frustoconical undersurface of a laterally enlarged portion thereof and a complementary seating surface of the stopper rod passageway, there being an insert threadedly engaged with one of the carrier element and stopper rod body at a position above a laterally enlarged portion of the carrier element, with further sealing means disposed between said insert and the carrier element. Preferably the insert is a nut screwed down onto a washer which compresses the further sealing means.

Abstract: A ceramic material made of a skeleton reaction-bonded silicon powder is distinguished by an open-cell pore structure produced by using a matrix of an appropriately shaped polyurethane foam structure. For the preparation, a foam matrix is coated with a suspension of silicon powder, synthetic resin and solvent and is subjected to a heat treatment, during which the foam matrix is expelled and the silicon is stabilized. The thermally and chemically stable product can be used, for example, as a filter medium for metal melts, as a catalyst carrier, or as a boundary medium between the flame zone and unignited combustible mixtures in burners.