SPS versus EB-PVD YSZ TBCs: Durability under Thermal Cycle in Thermal Gradient Environment

One important question lasting in the thermal spray community is the knowledge if suspension plasma spray (SPS) ZrO2-8wt%Y2O3 (YSZ) thermal barrier coatings (TBCs) can reach the performance levels of their electron-beam physical vapour deposition (EB-PVD) counterparts, and to eventually replace them as the state-of-the-art TBC for aviation gas turbine engine blades. This work aims at bringing some important clarifications on this subject. The SPS YSZ TBCs were engineered using industry-produced ethanol-based suspensions (from 25wt% to 75wt%) provided Innovnano, Saint-Gobain and Treibacher. The Mettech Axial III plasma spray torch and the Polycontrols M40 suspension feeder were employed to manufacture the SPS YSZ TBCs. The benchmark EB-PVD YSZ TBCs (including the Pt/Al bond coat) were manufactured by a private industrial contractor. All TBCs were deposited on single-crystal Rene N515 substrates. The bond coat material for the SPS YSZ TBCs was the NiCoCrAlY+HfSi; produced via air plasma spray (APS). The performance comparison amongst all these TBCs in thermal gradient cycling (5 min hot & 2 min cool cycles) was undertaken via a thermal gradient laser-rig testing system. These are released results from the Surftec Thermal Spray Industrial R&D Group of the National Research Council of Canada (NRC).