An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.
BACKGROUND OF THE INVENTION
This invention concerns an electromagnetic valve for controlling the flow of molten, magnetic metal, e.g., the flow of molten steel exiting a tundish used in a continuous casting system. The Government of the United States of America has rights in this invention pursuant to Cooperative Agreement No. DE-FC07-93ID13205 awarded by the U.S. Department of Energy.