| 摘要 |
PURPOSE:To economically and comparatively easily prevent constraction and even clogging of an inner hole for a long time without using a mechanical method of injection of inert gas, etc. CONSTITUTION:At least the inner hole 1 surface layer part in contact with molten steel is composed of 40-89wt.% calcium zirconate mainly containing CaO.ZrO2 as a mineral composition, 10-35wt.% graphite and 1-30wt.% crystal stabilized calcium silicate mainly containing 2CaO.SiO2 and 3CaO.SiO2 as the mineral composition, and after organic material binder is adder, kneaded and formed, calcination is executed in the non-oxidizing atmosphere. In this way, without causing deterioration in structure of a refractory, the constraction and further the clogging of the inner hole caused by non-metallic inclusions of alpha-alumina, etc., can be stably restrained for a long time. |
