A Tribological Investigation of Carbon-Carbon Composites and the Effect of Roughness and Waviness Parameters on Friction Performance

Friction tests for two types of carbon-carbon (C-C) composites were performed using a sub-scale aircraft brake dynamometer for 100 stops. Worn surface profiles were measured using a surface profilometer. Roughness and waviness parameters from the profilometry measurements were compared to weight loss, thickness loss, effectiveness, stop time, and torque for each C-C composite type. The results show that when roughness is analyzed, for an increase in torque and effectiveness and a decrease in stop time, there is a decrease in skewness and high spot count; and an increase in maximum valley depth, mean spacing of local peaks, and mean arithmetic wavelength. For waviness profiles, for an increase in torque and effectiveness and a decrease in stop time, there is a decrease in skewness; and an increase in high spot count, maximum valley depth, mean spacing of local peaks, and mean arithmetic wavelength. Furthermore, there are differences in both friction performance and surface topography between the CC composite types which can be attributed to the differences in fiber orientation and microstructure at the wear surfaces.