Characterization of contact parameters and fretting wear behavior of T-800 coating on Inconel 718

Fretting wear is a complex phenomenon that occurs at component interfaces that are subjected to low amplitude oscillation under high contact pressure. In turbomachinery fretting also occurs at the blade tip interfaces where shrouds are machined. To diminish the fretting damage coatings are applied to the blade tips. The aim of this work is to study the wear mechanism by point contact at room temperature and characterize the friction behavior and the fretting wear of Tribaloy T-800 coating, applied by plasma spray on an Incone718 superalloy. Some wear test of Tribaloy by pin-on-disc, ball-on-disc and block-on-ring can be found in literaure. Experiments were conducted with a self made test rig where a nominal spherical surface was pressed against a flat surface of the same material . The mating surfaces were worn with an alternating relative displacement with an amplitude of 150 μm, at a frequency of 100 Hz for 5×106; 10×106; 15×106 wear cycles and two normal load. The hysteresis cycles, namely the tangential contact force against the relative displacement, were measured throughout the experiment and the contact parameters (friction coefficient and contact stiffness) as function of wear cycles were obtained. At the end of the wear process, the three-dimensional topography of mating surfaces were measured by focus variation technology and observed through a SEM analysis. Loss volume during the wear processes were obtained by topography measurements.