Enhanced Experimental Testing of New Erosion-Resistant Compressor Blade Coatings

Performance differences between bare 17-4PH steel V103 profile (NACA 6505 with rounded leading edge (LE) and trailing edge (TE)) gas turbine engine axial compressor blades, and those coated with either a chromium-aluminum-titanium nitride (CrAlTiN) or a titanium-aluminum nitride (Ti_xAl_1−xN) erosion-resistant coating were tested. A coating thickness of 16 μm was used, based on experimental results in the literature. Coatings were applied using arc physical vapor deposition at the National Research Council of Canada (NRC). All blades were tested under identical operating conditions in the Royal Military College of Canada (RMC) turbomachinery erosion rig. Based on a realism factor (RF) defined by the authors, this experimental rig was determined to provide the best known approximation to actual compressor blade erosion in aircraft gas turbine engine axial compressors. An average brown-out erosive media concentration of $4.9 g/m3 of air$ was used during testing. An overall defined Leithead–Allan–Zhao (LAZ) score metric, based on mass and blade dimension changes, compared the erosion-resistant performance of the bare and coated blades. Blade surface roughness data were also obtained. Based on the LAZ Score, CrAlTiN-coated blades performed at least 79% better than bare blades, and Ti_xAl_1−xN-coated blades performed at least 93% better than bare blades. The Ti_xAl_1−xN-coated blades performed at least 33% better than the CrAlTiN-coated blades. Extrapolation of results predicted that a V-22 Osprey tiltrotor military aircraft, for example, could fly up to 79 more missions with Ti_xAl_1−xN-coated compressor blades in brown-out sand concentrations than with uncoated blades.