Influence of New Sol-gel Refractory Coating on the Casting Properties of Cold Box and Furan Cores for Grey Cast iron

New Sol-Gel coated sand cores made from coldbox and furan binder systems were investigated. The idea of the coating was to improve the surface quality of castings. Grey iron was cast on the cores in a sand casting process. The effect of the high temperature of the melt on the cores was assessed by measuring the heating curves.

The viscosity of the coating, moisture content and the permeability of the cores were evaluated. The surface quality of the castings was investigated using SEM and OM. The results show that the moisture content of the cores affected the permeability. In furan cores the vapour transport zone (VTZ) when in contact with the melt is larger than it is in a coldbox which means the furan cores have higher moisture content.

The new sol-gel coating has the potential for improving the surface quality of castings without negative effects on the graphite distribution. The surface of castings made using the new sol-gel coated furan cores show better surface quality than those made using the coldbox.