THE FRICTIONAL PERFORMANCE OF CARBON-CARBON COMPOSITE MATERIALS IN THE PRESENCE OF HYDRAULIC FLUID, RUNWAY DEICER AGENT, AIRCRAFT DEICER AGENT AND SEA-SALT WATER

摘要

This paper concentrates on the frictional performance of two commercial carbon-carbon composite materials. "Two-directional" (2D) randomly chopped pitch fiber in charred resin matrix finally densified with smooth laminar CVI and "Three-directional" (3D) non-woven ex-PAN fibers with rough laminar CVI matrix. To evaluate the effect of various contaminants on friction performance, these materials were treated with hydraulic fluid (HF), runway deicer (RDI), aircraft deicer (ADI) and sea-salt water (SW) and their frictional performance was evaluated using a sub-scale aircraft dynamometer. Tests were performed at 50 percent Relative Humidity (50 percent RH) and different braking conditions simulating 12.5, 25, 50 and 100 percent normal landing energy landings (NLE). Pre-exposure of the C/C samples to contaminants significantly influenced the frictional performance when compared to virgin samples (samples without contaminants). When contaminants were present the average coefficient of friction decreased by approximately 30 percent - 50 percent. Wear of materials could not be established unambiguously, since several samples exhibited again of mass owing to the strong oxidation processes and the interaction with contaminants. Additional thermal analyses were also performed using thermo-gravimetric analysis (TGA). This analysis indicates that the presence of various contaminants can also affect the kinetics of C/C oxidation. Generally, all studied contaminants accelerate the oxidation rate of C/Cs, and this process begins at significantly lower temperatures.