A dual platform theory for carbon-based material oxidation with reaction-diffusion rate controlled kinetics.

The combustion of carbon-based materials in a high speed stream of dissociated air is analyzed, together with the oxidation mechanism from reaction rate controlled regime through the transition to diffusion controlled oxidation. The product of the heterogeneous reaction of carbon with oxygen is known to be CO and CO2, and CO2 is generally usually neglected when surface temperature is higher than 1000K in many literatures. However, we find that CO2 plays an important role in the whole oxidation processes, and can't be ignored through the three regimes. It is shown that two different platforms existed in the diffusion controlled regime. The first platform results from a reaction of the predominant CO2 product, and the other is due to the predominant CO product reaction. In fact, the concepts of "fast" reaction and "slow" reaction are not proper, since the two are the extreme cases of the general model we proposed. As surface temperature rises, the oxidation process will change automatically from nominated "fast" reaction to " slow" reaction. The dual platform theory has been confirmed by several experimental results. [ABSTRACT FROM AUTHOR]