Coatings for Fluid Erosion Protection

Gas turbine engine fan blades experience leading edge erosion caused by water ingestion due to aircraft taking-off and landing in wet runways. The eroded leading edge exhibits irregular pitting and tends to flatten after extensive operations; hence, changing the optimal aerodynamic shape of the edge. This results in turbulent flow over the fan blade which leads to decreased fan efficiency and increased engine fuel consumption. MDS Coating Technologies previously developed a coating optimized to protect the leading edge of fan blades and demonstrated the coating’s capability to increase durability and aerodynamic performance via rig testing and flight demonstrations.

An initiative to further improve the durability of blades with an advanced coating was launched. New ceramic coatings were deposited by physical vapor deposition in an industrial machine. Several coatings of varying compositions and architectures were applied to specialized coupons, which were first assessed using cavitation tests based on ASTM G32 standard. A selection from the most promising candidates were deposited on segments of leading edges from several fan blades from different jet engines. These coupons were tested under very aggressive water droplet impingement: applying up to 100 passes of 2 mm diameter droplets accelerated to Mach 2 speeds. When compared to uncoated fan blade leading edge fragments from the same jet engines, the coatings delayed the onset for surface damage (i.e. increased the incubation period), reduced the area affected by material loss and diminished the depth of the largest pit.