Interface Reaction between Furan Resin Mold Coated with Inorganic Compounds and Spheroidal Graphite Cast Iron Melts

In the preceeding papers by the authors, it was reported that the abnormal structure which appears on the interface of spheroidal graphite cast iron/non-coated furan resin mold is formed by the interface reaction between the iron melts and the sulfur system gases contained in thermal decomposition gases on the furan resin mold. In this paper, some examinations were made on the interface reaction between the furan resin mold to be coated with several basic inorganic compounds and the spheroidal graphite cast iron melts ; namely fundamental examinations were made regarding measures to prevent the appearance of abnormal structures. Magnesium oxide and magnesium carbonate coatings have no more effect than screening thermal decomposition gases (the sulfur system gases) on the furan resin mold whereas calcium oxide and dicalcium silicate coatings demonstrate both screening and absorption effects on the sulfur system gases. Calcium carbonate displays the gas curtain effect by generating CO2 gases on thermal decomposition and exerts a powerful absorption effect on the sulfur system gases to form nascent calcium oxide. It was found that 2CaO·SiO2+CaCO3 (3+1) is the most effective inorganic compound as coating materials to prevent the appearance of abnormal structures.