Effect of oxygen on the wettability and interfacial reaction between the DD5 superalloy and ceramic shell

The sessile-drop method in vacuum environment was developed to study the wettability and interfacial reaction between the DD5 superalloy melt and Al2O3-based ceramic shell. The results show that the content of oxygen in superalloy can affect the wettability and interfacial reaction between alloy melt and ceramic shell. For the DD5 alloy/Al2O3-based ceramic shell system, the wetting angle decreases from 135.5° to 123.5° and the thickness of the interfacial reaction layer increases from 2.2 μm to 7.3 μm when the content of oxygen impurity increases from 4 ppmw to 21 ppmw. The interfacial reaction products between the DD5 alloy and Al2O3-based ceramic shell are mainly Al2O3. The Si element is also detected in a diffuse distribution on the surface of the interfacial reaction layer. The proportion of interfacial reaction area gradually increases with increasing temperature and oxygen impurity content. With the increase of oxygen impurity content, the active Al element in the alloy matrix is gradually enriched and adsorbed in the interfacial reaction layer. It leads to the increase of the interfacial reaction rate and has a significant effect on the reduction of the surface tension of the alloy melt.