Ambient and 550°C tribological behavior of select MAX phases against Ni-based superalloys

In this paper, we report on the tribological behavior, at 25 and 550 degrees C of the following layered (MAX phase) ternary carbides: Ti2AlC Cr2AlC, Ta2AlC, Ti3SiC2, Ti2AlN, Ti4AlN3, Cr2GeC, CrGaC, Nb2SnC and Ti2SnC, tested against Ni-based superalloys, SA (Inconel-718 and Inconel-600). The tests were performed using a pin-on-disc method at 1 m/s and 3 N. At room temperature, the wear rates, WRs, were relatively high (>= 10(-4) mm(3)/N-m) and no correlation was found between the WRs and the friction coefficients, mu. Third body abrasion is believed to be responsible for the high WRs at this temperature. At 550 degrees C, oxidized transfer films were identified on both contact surfaces. The tribofilms comprised mostly of Ni. Cr. Fe and O and resulted in low (< 10(-6) mm(3)/N-m) WRs and mu's < 0.5. This result implies that the tribo-oxidation products of the Ni-based SA tested herein (Inconel 718) are lubricious. (c) 2007 Elsevier B.V. All rights reserved.