High-temperature wetting behavior of molten Ni-based superalloy on Y2O3 ceramics with different surface microstructures

Abstract To clarify the reaction between molten alloy and ceramic shell in the process of investment casting and control the metallurgical quality of alloy, high-temperature wetting experiments of Ni-based superalloy melt on Y2O3 ceramics with different surface microstructures were carried out. The high-temperature wettability and interfacial interactions at 1873 K between Ni-based superalloy melt and Y2O3 ceramics were studied in the present paper. The results showed that the apparent equilibrium contact angle of alloy melt on the substrate firstly decreases from 90.8° to 75.9° and then increases to 87.7°, with the surface roughness of Y2O3 ceramic substrate changed from 0.859 µm to 2.253 µm. The contact conditions between melts and substrates are in accordance with the Wenzel equation, with the surface roughness of ceramic substrate varied between 0.859 µm and 1.311 µm. When that of the substrate continuously increased from 1.311 µm to 2.253 µm, the contact conditions between alloy melts and substrates were in accordance with the Cassie Baxter equation. Based on component analysis, it was found Al aggregated at the interface between Y2O3 ceramics and alloy melts, resulting in the formation of Y4Al2O9 and the change of surface tension of the alloy droplet in the process of high temperature wetting. Proper surface microstructure of the ceramic shell can ensure that the melt has enough filling ability and reduce the melt pollution caused by the reaction between melt and ceramic.