Thermal analysis of bulk carbon-carbon composite and friction products derived from it during simulated aircraft braking

Friction layer and friction debris samples obtained from commercially available carbon-carbon composite brake material (3D, C/C PAN CVI) by sub-scale dynamometer testing at 50% relative humidity and 100% normal aircraft landing energy have been characterized by multiple thermo-analytical techniques to investigate adsorption/desorption phenomena of physically bonded moisture and formation and decomposition of oxygen-containing structures. Thermogravimetric Analysis/Fourier Transform Infrared Spectroscopy, Temperature Programmed Reduction and Pyrolysis-Gas Chromatography-Mass Spectrometry experiments with friction layer and friction debris were accompanied with release of H₂O, CO₂ and CO on heating. These products are not observed when comparable analyses with the bulk brake material were performed. These data reflect significant oxidation of the original brake material and indicate that gaseous products (carbon oxides, H₂O) are released from the modified brake material during heating to temperatures approximating those experienced during typical aircraft braking.