PURPOSE: To suppress the Al in an exothermic pad with which molten metal contacts thoroughly and to prevent the formation of a hardened layer, by providing the coating layer of a refractory mold coating material wherein the amt. of the metallic nickel powder to be added is limited on the surface of said pad.
CONSTITUTION: Zircon, chromite, magnesia or the like is commonly used as a refractory mold coating material. The suitable ratio of the metallic nickel powder to be added into the mold coating material is 40W75wt%. It is not possible to suppress the Al in the pad thoroughly at the lower limit or below and the coating of the material is difficult to coat at the upper limit or above because viscosity increases. The reasons for selecting nickel for the metal to be added lies in the high effect of preventing diffusion of Al, the freedom from the factor to deteriorate the material in spite of the diffusion of the nickel itself into the molten steel, the ease of application and inexpensiveness.
KAI TOSHIO
KAWAUCHI TOORU
NAKAGAWA SHINJI
RYOMEI GIKEN KK