Abstract: Nanoindentation experiments were made on pyrocarbon of samples with single phase before or after high-temperature heat treating, and of the 3DC/C composites. Nanohardness and elastic modulus were measured. Loading and unloading curves were analyzed. It was found that there was only elastic distortion happening for the single phase samples before heat treating, but the plastic deformation also happened for the heat-treated samples. Values of elastic modulus are 33.84 and 4.65 GPa for single phase samples before and after heat treating, respectively. The large difference is due to the structure transformation from turbostratic structure to graphite structure. The value of elastic modulus was30.08 GPa for the C/C composite pyrocarbon.

Key words: elastic modulus, nanohardness, nanoindentation, pyrocarbon, C/C composites