Investigation and simulation of the shear lip phenomenon observed in a high-speed abradable seal for use in aero-engines

Abradable seals are used in the compressor sections of aero-engines, and their performance affects engine efficiency and durability. The sliding-induced surface damage between a type GH4169 turbine blade and a CuAlNiG seal coating was investigated under simulated working conditions using an improved high-speed rubbing test rig. The influence of different linear speeds (150, 300 m/s), incursion rates (5, 50, 500 mu m/s) and environment temperatures (300, 450 degrees C) were researched. According to variations in weight and height measurements of the blade test samples, and based on observations of the blade wear scar macro-morphologies, it was found that blade wear with a prominent shear lip increases with linear speed and temperature but decreases with incursion rate. The surface and cross-section morphologies, phase components of the blade and coating wear scars were analyzed using SEM, EDS and XRD. The formation mechanism of the shear lip was revealed for the first time. It was found that a double-layer shear lip was produced by the combined action of a shear mixed layer and blade matrix softening, both of which resulted from high-intensity frictional heating. (C) 2017 Elsevier B.V. All rights reserved.