Wettability and interfacial reactions of a low Hf-containing nickel-based superalloy on Al2O3-based, SiO2-based, ZrSiO4, and CoAl2O4 substrates

Abstract To understand the wetting behavior and interfacial phenomena between molten superalloys and ceramic materials, the wettability and interfacial reactions of a low Hf-containing Nickel-based superalloy on the Al2O3-based, SiO2-based, ZrSiO4, and CoAl2O4 substrates were studied using the sessile drop method at 1773 K. The wetting angles of the alloy on the Al2O3-based, SiO2-based, ZrSiO4, and CoAl2O4 substrates were 141.4°, 143.5°, 135.7°, and 128.4°, respectively. This indicated that the wettability of the alloy on the Al2O3-based substrate was comparable to that on the SiO2-based substrate, and the wettability of the CoAl2O4 system was the best among the four systems. The microstructure characteristics of the interface implied that Hf has a strong tendency to react with ceramic substrates, even at low contents. Additionally, the interfacial reactions transformed the Al2O3-based, SiO2-based, ZrSiO4, and CoAl2O4 ceramic substrates into (Al2O3 + HfO2), (Al2O3 + HfO2), (Al2O3 + HfO2 + ZrO2), and (Al2O3 + HfO2 + Co), respectively, which were in contact with the alloys. The experimental results demonstrated that the wettability of the system was governed by the properties of the reaction products.