E. Matte, L. Ajdelsztajn, B. Jodoin, University of Ottawa, Ottawa, ON, Canada; P. Marcoux, Vac Aero International Inc., Boucherville, QC, Canada
Gas turbine engine components are subjected to rigorous mechanical loading conditions, high temperatures, and corrosive/erosive media, leading to mechanical problems such as fretting. Fretting occurs when assemblies of components such as blade and disk attachment surfaces are subjected to vibrations. It leads to a cyclic reciprocating relative motion of extremely small amplitude between the two mating surfaces and results in damage much greater than that suggested by the small magnitude of the oscillatory movement. The anti-fretting coatings currently in use in land-based gas turbines are Cu-37%Ni-5%In and are sprayed onto the gas turbine parts using the plasma spraying process. This coating allows easy disassembly of components where tight fits, compounded with high pressure and fretting, might otherwise create a weld during engine operation. Since the plasma spraying process has been developed and used for many decades, the development of enhanced anti-fretting CuNiIn coatings, as sought by the turbine manufacturers, requires in all probability the use of new coating technologies as the plasma spraying process has been optimized and has reached its full potential many years ago. In particular, a coating process allowing a superior control of the coating microstructure with reduced oxidation is required in order to obtain new and possibly superior fretting properties.
The objective of this work is to produce anti-fretting coatings using the Cold Gas Dynamic Spraying (CGDS) process according to turbine manufacturer specifications and evaluate if the coatings obtained are superior in performance to similar coatings produce by plasma spraying. These evaluations consist in as-sprayed microstructure evaluation and phase evaluation (optical and scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), X-ray diffraction, transmission electron microscopy (TEM)). Hardness and micro-hardness testing as well as bond strength testing are also performed.
Summary: The objective of this work is to produce anti-fretting coatings using the Cold Gas Dynamic Spraying (CGDS) process according to turbine manufacturer specifications and evaluate if the coatings obtained are superior in performance to similar coatings produce by plasma spraying. These evaluations consist in as-sprayed microstructure evaluation and phase evaluation (optical and scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), X-ray diffraction, transmission electron microscopy (TEM)). Hardness and micro-hardness testing as well as bond strength testing are also performed.
