Kinetic Analysis of the Gasification of Diamond

Abstract

Diamond is the ultimate state of carbon crystal. However, a transformation from diamond to graphite during gasification occurs under oxidizing atmosphere. The gasification behaviors of diamond vary with the reaction gas composition and temperature.
There has been no kinetic study on the diamond gasification. Most of the interest in this area has been related to diamond growth.
The change of morphology of diamond surface and the crystallographic orientation between the diamond and the graphite formed was presented in a previous study.
In this study, the gasification of natural diamond was investigated using TG-DTA. Kinetic analysis was performed on the basis of Langmuir-Hinshelwood type equation, in which some rate constant was modified from the previous study for coke gasification. SEM observations of the diamond surface were carried out in order to clarify the change in surface morphology. Moreover, the simultaneous gasification of diamond and graphite was carried out in order to clarify the difference in reactivity between ordinary graphite and graphite formed on the diamond during gasification.