Electron microscopic observation of fractures in carbonaceous materials produced by cracking of natural gas

Circulating natural gas at 900 deg. C in an agglomerate of crushed graphite powder results in the formation of a compact material with high mechanical properties. Electron microscopic observation of fracture in resilience and compression specimens have been carried on, expecting a correlation between their mechanical properties and micrographic aspects. Fracture proceeds across the graphite grains and through the surrounding pyrocarbon as well. Heat-treated materials exhibit poorer mechanical properties: these changes could not be evidence in the micro-fractographic aspects of pyrocarbon; they may however account for differences in the fracture of the graphite grains. (authors)