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Published online by Cambridge University Press: 20 February 2018
This paper investigates the role degradation of protective diffusion aluminide coating on Inconel 713LC used for CT blades of short-haul aircraft fleet played in having the blades prematurely retired from service at 6378 hours, as opposed to their pre-set service time of 10000 hours. The blade samples were subjected to various examinations; X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyse at the; tips, airfoil, as well as the base, transverse and longitudinal, sectioned and unsectioned. As affirmed by both the transverse and longitudinal sections examinations, it was established that thermal attack leading to deterioration of the coating was greater at the tip and airfoils of the blades (the hotter zones) and lesser towards the bases (colder zones). As a result, severe degradation of the core material at the tips and airfoils compared to the bases and more prevalent at the leading edges than trailing edges at the tips. The results further suggest that both active outward Ni diffusion and inward Al diffusion can coexist during exploitation of the blades in service. The study illustrates the role played by the aluminide coating in early failure of CT blades with the aim of bettering the surface coatings and enhancing coating technologies, managing CT blade material monitoring as well as to give insights on advancing CT blades maintenance practices.