Kinetic studies of the oxidation of highly oriented pyrolytic graphites

✍ Scribed by F. Rodriguez-Reinoso; P.A. Thrower; P.L. Walker Jr.

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 670 KB
• Volume: 12
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(74)90042-6

✦ Synopsis

Two

highly oriented stress-recrystallized pyrolytic graphites have been used to study the kinetics of the carbon-Op reaction. Experimental conditions ranged from 700 to 800°C with 0, pressures from 6 to 60 Torr. Activation energies were determined at 20 Torr 0, pressure and the order of reaction determined at 725-750°C. Prior to the reaction, specimens were outgassed at about lo-"Torr for 8-12 hr at 95(PC. The reaction was then followed by continuously monitoring the weight loss using a microbalance. An initial, high transient oxidation rate was shown to be due to surface irregularities at the basal piane edges. Oxidation then occurred at a constant rate (provided that the Ox pressure was not sigi~ifi~nt~y depleted) with an activation energy of 47-53 kcal/mole, which was shown to be due to the reaction of Or with carbon atoms at edges of graphite basal planes. There was no indication of retardation of reaction by concurrent formation of a surface oxygen complex. Reaction order was 0.5andO.6 for the two graphit,es.