Abstract
The burn-on of iron castings, namely chemical penetration, has posed as one of the main casting defects for a long time. However, no solution has yet been clarified for this intricate phenomena. In this paper, we discuss how the burn-on is affected with the SiO2 content of sands from the standpoint of wettability using the sessile drop method. The apparent contact angle between the sand grains and melt decreases with the formation of FeO slag at the interface, and stop the advancing by the dissolution of SiO2into the slag due to the increase in the melting temperature. The reason why chemical penetration defects can be prevented by the addition of coal dust into mold, is not only due to the decrease the FeO slag formation but also due to the ease of saturation of the slag with SiO2 to increase the melting temperature.
