Tribo-induced surface structure of Nickel-based superalloy at elevated temperature

Abstract An in-depth understanding of the tribo-induced surface structure and its correlation with friction and wear performance is a prerequisite towards controlling the friction and wear properties of materials at high temperature. Dry sliding ball-on-disc wear tests of nickel-based superalloy (Ni-16Cr-13Co-4Mo) were performed at 600 °C, 700 °C, 800 °C, respectively. The tribo-induced structure of the worn surface at different temperature were systematically analyzed. Effects of surface structure on the tribological properties of the alloy were also investigated. Results show that the tribo-induced surface structure of the nickel-based superalloy formed at high temperature is characterized by a tribo-layer consisting of a mixture of spinel oxides on the top and a thermal deformed region beneath, which are temperature-dependent. The friction and wear performance of the alloy was governed not only by the properties of the tribo-layer, but also by the structure of the substrate alloy in the deformed region, which played a supporting role to the tribo-layer. As the temperature further increased, the wear resistance decreased due to the deterioration of the supporting effect of the substrate alloy to the tribo-layer, which was resulted from the dissolution of the strengthening phase in the alloy under the thermal-mechanical coupling action at high temperature.