Microstructural investigations of carbon foams derived from modified coal-tar pitch.

•The microstructure of coal-tar pitch-derived carbon foams is examined.•Microspheres containing sp-bonded species are observed at 1000°C.•Above 1000°C the microspheres experience transformations in a non-aromatic pathway.•Microspheres are identical with the sp2-sp3 foams matrices at 2000°C.•The compressive strength depends on the concentration of sp-bonded carbon atoms.