Effect of Compressive Prestress on the Mechanical Properties of Isotropic Graphite.

Abstract

Compressive prestresses were applied to isotropic fine-grained graphite at room temperature (RT) and high temperature (2010°C). As a result, decrease in Young's modulus due to high-temperature prestressing was 56% which was much larger than the 6.4% that was due to RT prestressing. This finding was considered to be due primarily to difference in degree of preferred orientation of crystallites in the graphite on the basis of Bacon anisotropy factor (BAF) from X-ray diffraction measurement of the prestressed specimens. Furthermore, high-temperature compressive prestressing produced an increase in the strength of the isotropic graphite, although room temperature prestressing produced no such effect. The results obtained here suggest that isotropic graphite which is subjected to high-temperature compressive stress becomes anisotropic.