Kinetics of pore coarsening in glassy carbon

✍ Scribed by S. Bose; R.H. Bragg

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 625 KB
• Volume: 19
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(81)90075-0

✦ Synopsis

One third of the microstructure of glassy carbon (GC) consists of closed pores. Density measurements indicate that fhe total pore volume depends only on the heat treatment temperature and not on the heat treatment time, a characteristic of coarsening. The kinetics of coarsening of these pores on heat treatment has been investigated by analyzing the changes in specific surface area of the pores as determined by the small angle X-ray scattering (SAXS) technique. A part of the surface area change is due to thermal expansion induced microcracking. Both the superposition method after correcting the thermal expansion induced surface area change and the curve fitting method give an activation energy of 64 +_ 10 kcal/mole. This value is compared with the activation energies of various rate processes in graphite. A model of coarsening of the pores based on a vacancy migration mechanism is proposed.