Microstructural Characterization and Room-Temperature Erosion Behavior of As-Deposited SPS, EB-PVD and APS YSZ-Based TBCs

The erosion behavior at room temperature of as-deposited suspension plasma spray (SPS), electron beam physical vapor deposition (EB-PVD) and air plasma spray (APS) ZrO2-Y2O3 (YSZ)-based TBCs was investigated. All coatings were deposited on Inconel 625 alloy coupons. The same APS CoNiCrAlY bond coat was employed for all SPS and APS TBCs. The erodent material was 50-mu m alumina, and the impact angles were 15 degrees and 90 degrees. A total of 4 different types of SPS YSZ-based TBCs were tested, which consisted of two distinct columnar-segmented and two distinct columnar-grown microstructures. The EB-PVD and APS YSZ TBCs were employed as benchmarks. The erosion performance of the different TBCs in this study was ranked based on the coating volume loss after wear testing. The TBC microstructures and phase compositions were evaluated via scanning electron microscopy and X-ray diffraction. The erosion mechanisms of the different TBCs were compared by analyzing the cross-sectional and top surface microstructures of the as-deposited and eroded TBCs. These are released results from the Surftec Industrial R&D Group of the National Research Council of Canada.