Blades, vanes, and impellers in gas turbine compressors operate in dusty environments and are prone to degradation by solid particle erosion. Erosion of the impeller blades can lead to potentially catastrophic compressor failure. We propose a thin ceramic-metal composite (cermet) coating based on a sol-gel process that is designed to combat erosion effectively. The proposed coating process is simple, inexpensive, and does not use materials that are hazardous to the environment. The coating consists of metallic particles bound together, and to the substrate, via a ceramic matrix. The ductile phase provides erosion protection at higher impingement angles and the ceramic phase provides protection at lower impingement angles. By varying the type and concentration of powders in the sol, coatings with the desired erosion properties can be prepared. The thinness and smoothness of the coatings ensures that the fatigue properties are not undermined by the coating. During Phase I, erosion and high cycle fatigue resistance of the proposed coating will be evaluated on Ti-6Al-4V at ambient temperature. Phase II studies will include erosion and fatigue evaluation of the coatings in various simulated service conditions and tests on actual turbine engine components. The most promising coatings will be patented and licensed as protected technology for commercial use in Phase III. Helicopters, vertical/short take-off and landing aircraft, fighter jets, airlines and power plant turbine engines will benefit from the effective and economical protection afforded by the proposed coatings. Moving mechanical assemblies (MMAs) used in spacecraft and diesel engines will equally benefit from the hard and tough coatings developed in this proposal. Some of MMAs include bearings, gears, cams, bushings, seals, valves, nozzles, and pistons.
Keywords: Impeller, Erosion, High Cycle Fatigue, Titanium, Cermet, Protective Coatings, Sol-Gel Techniqu
