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A new concept of composite phase ceramic had been proposed for the topcoat of a durable thermal barrier coating (TBC) system which is one of the critical technologies for advanced turbine engines. The composite phase TBCs showed promising performance related benefits over conventional single phase TBCs, including durability, material affordability, thermal stability and low thermal conductivity. The present work is to continue the effort to exploring the TBC behaviors of erosive wear by solid particle erosion test and thermal cyclic shock by special burner rig test. In the erosion test, the investigation was focused on the most important characteristics of erosion test results using different characterization methods, including the variations of erosion damages with impingement angle and finally the effect of high temperature sintering. In the burner rig test, the TBC was exposed to a rapidly thermal cycling condition introduced by a high heat flux and high-velocity combustion torch. The TBC damages and failure modes were identified and explained in terms of microstructural observation and mechanism discussion. The composite phase c ? t 0 TBC demonstrated improved erosion resistance relative to a Gd 2 Zr 2 O 7 TBC and equivalent thermal shock resistance to a conventional 8YSZ TBC. Keywords air plasma spray Á burner rig test Á coating characterization Á erosion test Á thermal barrier coating This article is an invited paper selected from abstracts submitted for the 2020 International Thermal Spray Conference, ITSC2020 that was to be held from June 10-12, 2020, in Vienna, Austria. The conference was cancelled due to the coronavirus (COVID-19) pandemic. The paper has been expanded from the planned presentation.

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High-entropy alloys (HEAs) have great potential to be used as high-temperature materials and in coating material applications due to their combination of strength, ductility, thermal stability, wear, and oxidation resistance. In this work, a new HEA alloy based on NiCoCrAlSi composition was designed and deposited into metallic coatings by high-velocity oxy-fuel (HVOF) and air plasma spray (APS) processes, with the aim of developing new HEA bondcoats for thermal barrier coating (TBC) systems. The HEA coatings were analyzed for phases, microstructure and composition using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results showed that the BCC phase is the major phase present in the as-applied HVOF coating that was vacuum diffusion treated at 1080 °C. APS coatings of the same composition HEA alloy showed a two-phase structure consisting of the L12 and BCC/B2 phases. The HEA bondcoats produced by HVOF were tested for oxidation resistance at 1050 °C in air, and for thermal cycling resistance of the TBC comprising of the HVOF-applied HEA bondcoat and standard 8YSZ ceramic topcoat. The results showed internal oxidation in the HEA bondcoat during the high-temperature oxidation exposure, but no significant coating failure after 100 thermal cycles at 1150 °C.

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