PURPOSE: To increase the wall thickness of a ceramic layer by controlling the difference in the m.p. between ceramics and metal to a specific value and executing slow cooling at a prescribed cooling rate after solidification.
CONSTITUTION: Materials such as cast steel consisting of 0.05W2.0wt% C, 0.1W1.5% Si, 0.1W1.5% Mn and the balance Fe and impurities and ceramics consisting of 20W90% Al2O3 and the balance SiO2 and impurities are selected. The difference in the m.p. between the respective materials is controlled to ≤1,000°C. A sand mold 15 is formed in a circular cylindrical metallic flask 12. The molten metal and molten ceramics are poured therein and a drag 11 is rotated. The metal and ceramics are gravity-separated by the effect of centrifugal force and the thick-walled ceramic layer 2 is formed on the inside surface of the metallic layer 1 according to the such method. The casting is then slowly cooled at a cooling rate of ≤100°C/hr. The crack of the ceramic layer 2 is prevented by the difference in the coefft. of thermal expansion and the wall thickness thereof is increased.
SETO YOSHITO
KIMURA HIROYUKI
