Abstract
In this study, the effects of complex sulfides of cerium(Ce) and manganese(Mn) on the graphitization of flake graphite cast iron were investigated. To clarify the behavior of sulfides in cast iron, Mn and Ce were added individually or together. Mn formed a polygonal shaped compound with sulfur(S) in the cast iron and the growth stage of this compound was observed with time. Manganese sulfide did not act as a substrate for graphite crystallization. 0.2%Ce was added to the melt containing 0.6%Mn, 0.08%S in consideration of stoichiometric balance with the amount of S. When Ce added to Mn contained melts, MnS was surrounded by Ce and the latter formed a compound with S in the form of Ce2S3 immediately. After that, MnS and Ce2S3 formed spherical shaped compound as a result of eutectic reaction. Ce and Mn formed sulfides with S in the melt and these complex sulfides acted as substrates for graphite nucleation in the flake graphite cast iron melt, resulting in remarkable graphitization. In time, the complex sulfide separated to MnS on the ontside and Ce2S3 on the inside. This form of sulfide did not serve as a substrate for graphite formation.
