Room-Temperature Solid Particle Erosion Behavior of SPS-Deposited High-Entropy Zirconate Topcoats in Thermal Barrier Coatings

Corresponding: farnaz.bayat@mail.concordia.ca, christian.moreau@concordia.ca Abstract: Thermal barrier coatings enable higher operating temperatures in gas turbines by protecting metallic components from heat, but in real service conditions airborne particles can erode the ceramic topcoat and compromise coating lifetime. This study evaluates the room-temperature solid particle erosion resistance suspension plasma sprayed high-entropy zirconate (HEZ) topcoats developed for next-generation Thermal Barrier Coating (TBC). Coatings were deposited on IN-625 nickel-based superalloy substrates with an HVOF-sprayed bond coat (Amdry 386-2.5, Oerlikon Metco), overlaid with Suspension Plasma Sprayed (SPS) ceramic topcoats. Two high entropy zirconate (HEZ) coatings with a chemical composition of ((Y₀.₂Nd₀.₂Gd₀.₂Sm₀.₂Dy₀.₂)₂Zr₂O₇) were produced: columnar and dense vertically cracked (DVC). Their erosion resistance was then compared with reference yttria-stabilized zirconia (YSZ) coatings, with matching microstructures (1 DVC SPS YSZ and 1 columnar SPS YSZ). The objective is to decouple the effects of coating chemistry and microstructural architecture on erosion resistance at room temperature. Standardized solid particle erosion testing was conducted at room temperature to identify dominant material removal mechanisms and quantify performance differentials. The results provide insight into whether increased configurational entropy zirconates can enhance erosion durability relative to the conventional YSZ benchmark, with implications for high-wear aerospace and energy applications. Keywords: Thermal spray, Suspension Plasma Spray, Thermal Barrier Coating, Topcoat, High Entropy Zirconate, Erosion.