TiO2–ZnO/Ni–5wt.%Al composite coatings on GH4169 superalloys by atmospheric plasma spray techniques and theirs elevated-temperature tribological behavior

Abstract Ni–based composite coatings with different amounts of TiO2–ZnO were fabricated by atmospheric plasma spraying (APS) to protect GH4169 superalloy substrates against excess wear and friction at elevated temperatures. In addition, the influence of the simultaneous addition of the oxides on the microstructure, microhardness, and wear behaviour was investigated. According to the results, the simultaneous addition of TiO2/ZnO provides anti-friction and wear inhibition over 600 °C. In particular at 800 °C, the TiO2–ZnO/Ni–5wt.%Al composite coating (10 wt% TiO2 and 10 wt% ZnO were incorporated within Ni–5wt.%Al matrix) exhibits a superior lubricity and wear resistance compared to the Ni–5wt.%Al based coatings. The XRD, Raman, and TEM characterisations reveal the formation of a glaze oxide layer consisting of NiO, TiO2, ZnO and the in-situ production of ternary oxide (Zn2TiO4), which was primarily responsible for the tribological performance of the sliding wear contacts at the specific temperature.