Mesophase formation of coal-tar pitches used
for impregnant of C/C composites
for impregnant of C/C composites
(State Key Laboratory for Powder Metallurgy,
Central South University, Changsha410083, P.R.China)
Central South University, Changsha410083, P.R.China)
Abstract: By a polarized light optical microscopy with a hot stage, liquid-phase nuclear magnetic resonance 13C-NMR and 1H-NMR, X-ray diffractometry and scanning electron microscopy (SEM), the factors that affect the formation of mesophase in C/C composites, such as pressure, quinoline insolubles (QI) and heterocylic compounds, were analyzed. Further, the graphitizability of the resultant carbon was discussed. The results indicate that to some degree, QI contents accelerate the formation of mesophase at atmospheric pressure; while at high pressure, the coalescence and growth of mesophase spherules are impeded and the resultant coke produced from higher QI content pitch is harder to be graphitized. This is in agreement with the transfer of microstructure from domain anisotropy to fine-grained mosaics.
Key words: C/C composites; coal-tar pitch; mesophase; quinoline insolubles; graphitization