Erosion Resistant Coatings for Large Size Gas Turbine Engine Compressor Airfoils

Jet engine titanium compressor airfoils are susceptible to erosion damage ranging from a few percent loss in blade chord length in fighter engines to more significant erosion exhibited by helicopter engines operating in desert environments. The application of titanium nitride coatings on individual compressor airfoils have provided significant operational, maintenance and safety benefits for helicopter engines operating in desert environments. Yet, this technology has not been applied on large integrally bladed compressor rotors due to the challenge of coating large parts with diameters greater than 0.4 m and the more subtle erosion characteristic of jet engine compressor airfoils as compared to helicopter engines. However, a few percent chord loss in a titanium, integrally bladed compressor rotor is signicant in that the repair and replacement costs are much more expensive than for individual airfoils. Additionally, a few percent in chord loss decreases compressor performance and increases fuel consumption. The application of erosion resistant coatings on large, titanium compressor integrally bladed rotors via a cathodic arc physical vapor deposition process utilizing machines with sufficient coating capacity could potentially provide the necessary erosion protection within specified fatigue debit limits; hence, increasing the mean-time-between-repair interval, maintaining compressor performance and decreasing fuel consumption.