Analysis of geometrical effects on graphite oxidation through measurement of internal surface area

To investigate the geometrical effects on nuclear graphite oxidation in the regime where the chemical effect is the rate-controlling process, we introduce the concept of internal surface density into the Arrhenius-type reaction model and suggest how to determine it experimentally. Using the 16 different samples of IG-110 graphite, which have different ratios of external surface to volume, we obtained the value of internal surface density as 17 260 m−1. We found out that the external surface reaction is very small compared to the total reaction for the IG-110 graphite: the ratio of the external surface reaction to the total reaction was within 5%. Finally, we propose the following reaction equation for this material: r ‴ ( kg / m 3 s ) ≈ 2 552 000 · exp - 218 000 R · T · P O 2 0.75 .