Optimization of Anti-Erosion PVD Coatings for different Turbine Compressor Blade Alloys

Despite tremendous development in gas and steam turbine materials, erosion still remains as a challenge due to the progressive loss of material that results from solid particles entrained in the air ingested by the engine, in particular during landing and take-off in dust intensive environments. This loss of material and geometry of the leading and trailing edges of the blades and stators affects the overall performance of engine. Thus, PVD coatings deposited by cathodic vacuum arc have been thought as a solution to allow retention of compressor blades profiles maintaining the engine performance at a high level and lowering maintenance costs. The use of TiN coatings has been a known method for protection against erosion due to their hardness. In contrast, TiAlN coatings with comparatively higher hardness have been devised as a better alternative to TiN coatings.

In this particular work, monolayer PVD coatings were designed and applied on different substrate materials such like superalloy and Titanium alloys. The behavior of these coatings against solid particle erosion (SPE), water jet and cavitation erosion at room temperature has been tested. SPE has been used to evaluate the erosion durability at angles of 20° and 90°, using abrasive particles of Al2O3. Water jet erosion test was carried out using different angles and also compared to WCCo coating sprayed by HVOF. The resistance of coatings to cavitation erosion has been evaluated by the means of shockwaves generated by an immersed sonotrode.

Erosion mechanisms for different substrates and coatings have been investigated. The influence on erosion resistance of the design of substrate interface, coating thickness, hardness and residual stress of the coatings have been correlated to the erosion rate. All tested PVD coatings proved to have much higher erosion resistance than the substrate material.