Enhanced Experimental Testing of New Erosion Resistant Compressor Blade Coatings

Abstract

Performance differences between bare 174PH 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 chromiumaluminumtitanium nitride (CrAlTiN) or a titaniumaluminum nitride (TixAl1−xN) erosionresistant coating were tested. A coating thickness of 16 خ¼m 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 brownout 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 erosionresistant performance of the bare and coated blades. Blade surface roughness data were also obtained. Based on the LAZ Score, CrAlTiNcoated blades performed at least 79% better than bare blades, and TixAl1−xNcoated blades performed at least 93% better than bare blades. The TixAl1−xNcoated blades performed at least 33% better than the CrAlTiNcoated blades. Extrapolation of results predicted that a V22 Osprey tiltrotor military aircraft, for example, could fly up to 79 more missions with TixAl1−xNcoated compressor blades in brownout sand concentrations than with uncoated blades.