PURIFYING METHOD FOR METAL

摘要

PURPOSE:To enhance the heat conductivity and mechanical strength of a cooling pipe and to enable the repeated use over a long time by forming a sprayed layer of a substance not contaminating molten metal and havng a small difference in coefft. of thermal expansion between it and the matrix metal on the surface of the heat resistant metallic body of the cooling pipe. CONSTITUTION:A cooling pipe is put in molten metal held in a container, and by feeding a cooling medium to the pipe, purified metallic crystals are grown on the surface of the pipe. On the surface of the metallic body of the pipe a sprayed layer of a substance not contaminating the molten metal and having <=2X 10<-5> deg.C difference in coefft. of thermal expansion between it and the matrix metal, e.g. a TiB2 sprayed layer is formed. It is preferable to grow metallic crystals on the surface of the pipe while rotating the pipe. The crystal stuck pipe is separated from the residual molten metal and heated to melt the purified metallic crystals.