Effect of solidification of mold fluxes on the heat transfer in casting mold

Crystallization of molten mold flux film has been observed using a confocal scanning laser microscope (CSLM) with an infrared furnace. The observation has indicated that mold flux of larger basicity (CaO/SiO2=1.41) starts crystallizing directly in liquid phase at temperatures >1373 K, and shows a faster growth rate of crystalline than that of smaller basicity (CaO/SiO2=0.96). Cross-section of solidified fluxes shows that the shrinkage due to the crystallization is more for larger basicity flux than for smaller one. This difference implies that thermal resistance at mold/mold flux film interface arises from the solidification and crystallization of the flux film.