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Abstract
The interface between titanium compressor blades and rotors of jet engines was studied to determine the mechanisms responsible for problematic deteriorations of protective Cu-Ni-In coatings. Results indicated that at operational temperatures of 221 °C, titanium from the uncoated disk was transferred to the softer Cu-Ni-In coating on the blade. This in turn created titanium on titanium contact and resulted in fretting wear. At higher temperatures of 454 °C, copper segregation appears to be the dominant deterioration mechanism. In order to simulate these wear modes and evaluate candidate coatings, a unique testing procedure was developed that included a range of gross-slip scale displacements. Cobalt, molybdenum, tungsten carbide, and Nickel-based coatings were evaluated by this testing procedure that first involved a low-cycle series of gross-slip displacements (125μm), followed by a higher cycle series in a reduced (25μm) gross-slip regime. Results of the study revealed that an unlubricated pure-cobalt coating could protect the blade without damaging the disk at elevated temperatures. While no coatings performed exceptionally at lower temperatures, pure molybdenum exhibited some promise.
