Carbon fibre reinforced carbon produced by polymer impregnation and pyrolysis

Carbon fibre reinforced carbon (C/C) is an attractive material for intermed iate and high temperature applications due to its specific properties like low density, high strength and chemical stability. Unfortunately the materi al oxidizes, so that in an oxidative environment a protective coating has t o be applied. Polymer impregnation and pyrolysis is a cost effective produc tion technique to produce C/C materials. In the present work, an abstract o f a research program funded by the German Science Foundation (DFG), the mec hanical properties of C/C as a function of processing temperature and test temperature have been described. In the program the behaviour of two-dimens ionally reinforced (2D) material and unidirectional reinforced (1D) materia ls has been investigated. All materials experience a strength reduction as a result of carbonization of the polymer matrix at temperatures up to 1000 degrees C. An additional heat treatment above 1000 degrees C causes a parti al recovery of the strength. The 1D C/C material shows up to testing temper atures of 1800 degrees C a 10% loss of strength, whereas for the 2D C/C the strength increases by 10% at 1500 degrees C in comparison with the room te mperature results.