Effect of Kaolin/TiO₂ Additions and Contact Temperature on the Interaction between DD6 Alloys and Al₂O₃ Shells

In this study, the effects of kaolin and TiO2 additions on the interaction between DD6 alloys and Al2O3 shells were investigated at 1550 and 1600 °C, respectively. Through the use of optical microscopy and scanning electron microscopy, the phase composition and microstructure of the shells and the alloys were studied, and the interaction mechanism was clarified. The results indicate that the shells adding kaolin and TiO2 had a relatively weak interaction with the alloys at 1550 °C, and no significant sand adhesion could be observed. As the contact temperature was increased to 1600 °C, the alloy melt could permeate into the shells, resulting in the generation of a thick sand adhesion layer. The thicknesses of the attached layers in the alloys, which contacted the shell with kaolin and TiO2, were 120 and 220 μm, respectively. No significant chemical products could be detected in the interaction layer, meaning that only physical dissolution of the shell refractory occurred. This study provides an experimental foundation for improving shell performance and offers valuable references for further research in related fields.