HEATING TREATMENT OF CALCINED CERAMICS CONTAINING BN AND SOLIDIFYING DEVICE FOR CONTINUOUS CASTING

摘要

PURPOSE:To improve quality by subjecting BN-contg. ceramics obtd. by calcination in an atmosphere contg. H2 and NH3 to a heating treatment at a specific temp. or above in an atmosphere without contg. the H2 and NH3. CONSTITUTION:The sintered ceramics contg. BN is produced by calcination in the atmosphere contg. the H2 and NH3. This sintered body is then subjected to the heating treatment for a prescribed period of time at about 500 to 1400 deg.C in in the case of a high H2 content and about 350 to 800 deg.C in the case of a high NH3 content in the atmosphere without contg. the H2 and NH3 to obtain the good-quality sintered ceramics contg. the BN which can suppress the generation of bubbles. This sintered ceramics contg. BN is used for an annular break ring 5 of the solidifying device for continuous casting consisting of a tundish 1, a front nozzle 2 connected thereto and a feed nozzle 4 connecting the tundish 1 and a mold 3, by which the generation of the bubbles by the H2 or NH3 is suppressed and slabs having good quality are obtd.