Journal of Materials Science

, Volume 18, Issue 9, pp 2671–2678 | Cite as

Effect of heat treatment temperature (HTT) on density, weight and volume of glass-like carbon (GC)

  • Bhola N. Mehrotra
  • R. H. Bragg
  • A. S. Rao


Room temperature measurements have been made of the density, weight and linear dimensions of glass-like carbon (GC) that was heat treated in the temperature range of 1000 to 2700‡ C for three hours in inert gas atmosphere. The density of GC decreased with increase in heat treatment temperature (HTT), reaching a maximum decrease of 12.4% at 2700‡ C; and the weight loss increased with increasing temperature to a maximum of about 1.9%. The volume increased and showed a quadratic dependence on the HTT, reaching a maximum value of about 10.2%. Subsequent application of hydrostatic pressures up to 1551 MPa (225 000 psi) produced only a small increase in bulk density. It is concluded that the weight loss is not the major cause of the density decrease, instead the volume expansion of pores is mainly responsible for this behaviour. The weight loss is suggested to be due to the release of the last vestiges of hydrogen and the volume expansion is shown to be due to two different mechanisms operating in different temperature regimes. A gas pressure mechanism is predominant up to the HTT of 1600‡ C and at greater HTT thermal stress mechanism predominates. The irreversibility of the dimensional change is proposed to be due to the ratchet-like [1] nature of microstructure that is developed during heating of the GC.


Bulk Density Thermal Stress Hydrostatic Pressure Temperature Regime Volume Expansion 
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Copyright information

© Chapman and Hall Ltd. 1983

Authors and Affiliations

  • Bhola N. Mehrotra
    • 1
  • R. H. Bragg
    • 1
  • A. S. Rao
    • 1
  1. 1.Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral EngineeringUniversity of CaliforniaBerkeleyUSA

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