Some active metal oxides (Al 2 O 3 , TiO 2 , and Cr 2 O 3 ) were selected as dopants to the Al 2 O 3 -based ceramic shells for investment casting of K417G superalloy. The effects of dopant types and contents (0, 2, 5, and 8 wt.%) on the wettability and interfacial reaction between the alloy and shell were investigated by a sessile-drop experiment. The results show that increasing the Al 2 O 3 doping contents (0-8 wt.%) reduces the porosity (21.74%-10.08%) and roughness (3.22-1.34 μm) of the shell surface. The increase in Cr 2 O 3 dopant content (2-8 wt.%) further exacerbates the interfacial reaction, leading to an increase in the thickness of the reaction layer (2.6-3.1 μm) and a decrease in the wetting angle (93.9°-91.0°). The addition of Al 2 O 3 and TiO 2 dopants leads to the formation of Al 2 TiO 5 composite oxides in the reaction products, which effectively inhibits the interfacial reaction. The increase in TiO 2 dopant contents (0-8 wt.%) further promotes the formation of Al 2 TiO 5 , which decreases the thickness of the interfacial reaction layer (3.9-1.2 μm) and increases the wetting angle (95.0°-103.8°). The introduced dopants enhance the packing density of the shell surface, while simultaneously suppress the diffusion of active metal elements from the alloy matrix to the interface.
KOU et al. (2026) studied this question.