Fretting Wear Resistant Coatings for Turbine Engine Applications

Attachment areas in the regions of rotating components of gas turbine engines degrade due to fretting wear and fatigue. Plasma sprayed coatings are often used to protect these regions. A thin, dense, Ti(C, N) composite coating based on sol-gel process is proposed. The simple, cost-effective sol-gel process will coat complex shapes and will provide superior performance against fretting wear. Diamond like carbon (DLC) coating applied by plasma-assisted chemical vapor deposition (PACVD), TiN and TaN coatings applied by reactive gas magnetron sputtering are also proposed as alternatives. During Phase I, the coatings will be applied on Ti-6Al-4V and Rene 80 alloys. Fretting wear resistance of the coatings will be evaluated at ambient temperature using the block-on-ring technique. Extent of wear will be determined using weight loss measurements, and the wear mode will be characterized using microscopy, surface analysis, and microhardness measurements. Adhesion of coatings to substrate will be evaluated through scratch tests. Phase II studies will include fretting wear evaluation of the coatings at elevated temperatures, fretting fatigue and abrasion wear tests, and tests on actual turbine engine blades. The coatings will be licensed for commercial use in Phase III. The abrasive wear testing is proposed as a Phase I option.