The Oxidation of Graphite at Temperatures of 600° to 1500°C and at Pressures of 2 to 76 Torr of Oxygen

The oxidation of graphite is an interesting reaction due to its technological importance. Volatile reaction products of carbon monoxide and carbon dioxide are formed at all temperatures above 25°C. Below 800°C a small amount of surface oxide is also formed. The rate of oxidation below 800°C is limited by a chemical process having an energy of activation of 39 kcal/mole. Above 800°C the reaction is limited, by either a chemical process or by gaseous diffusion of oxygen through the products of reaction. The transition between the two processes depends on the pressure, sample size, and the nature of the reaction system. Gravimetric, pressure change, and mass spectrographic methods were used to study the kinetics of the oxidation reaction. The discovery of the surface area effect greatly aided the study of the primary chemical reaction up to 1000°C and the diffusion‐controlled region of oxidation. Using small samples having surface areas of 0.13 cm 2 rates of oxidation of were measured in a static system. Experimentally the rate of oxidation of carbon is governed by three factors (i) the primary chemical reaction, (ii) the diffusion‐controlled reaction, and (iii) the theoretical rate based on collision theory.