Influence of heat treatment on microstructure and properties of highly textured pyrocarbons deposited during CVD at about 1100 °C and above 2000 °C

The influence of heat treatment up to 2900 °C on microstructure and mechanical and physical properties of highly textured pyrocarbons deposited at low (approx. 1100 °C) as well as at high temperature (above 2000 °C) was characterized by X-ray diffraction, electrical conductivity measurements, thermal expansion investigations, indentation, and three-point bending tests. The results of both XRD and physical properties measurements reveal that the low temperature pyrocarbons (LT PyC) graphitize easier and better than the investigated high temperature pyrocarbons (HT PyC) and that there is a real potential to convert LT PyC to HOPG (higly oriented pyrolytic graphite) via heat treatment at very high temperatures. The results of the mechanical tests (indentation and three-point bending tests) carried out on the samples before and after heat treatment show a good correlation with the microstructural changes due to the heat treatment.