Insights into the static friction behavior of Ni-based superalloys
P Stoyanov and L Dawag and WJ Joost and DG Goberman and S Ivory, SURFACE & COATINGS TECHNOLOGY, 352, 634-641 (2018).
The purpose of this study was to provide a better understanding of the static friction behavior of Ni-based superalloys over a wide range of temperatures. The static friction coefficient was investigated using a custom-built high-temperature apparatus in a flat-on-flat contact configuration. Measurements were performed on Inconel 718, using a variety of counterface materials (i.e. Ni-Cr coating, ME16, Ti-6246 and Inconel 718). The static friction coefficient was overall higher for the experiments at elevated temperatures for all counterface materials against Inconel 718. Ex situ analysis by means of FIB/SEM and XPS revealed the formation of metal oxide layers on the surfaces of the different alloys after testing at elevated temperature. In addition, atomistic simulations were performed in order to elucidate the interfacial mechanism leading to the differences in static friction. The observations of the simulations correlated well with the experiments, where the shear strength of the frictional interfaces was evidently higher for the oxide-on-oxide systems compared to the nickel-on-nickel.
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