The Kinetics of Oxidation of High Purity Nickel

摘要: The effect of time, temperature, and surface pretreatment on rate oxidation high purity nickel is studied for the temperature range 400°–750°C using a vacuum microbalance technique. data are compared to previous studies in literature with other metals. Oxidation interpreted terms parabolic law classical theory diffusion.Large deviations from found occur during initial stages reaction smaller over long periods especially at low temperatures. However, reasonable values heat entropy activation over‐all can be calculated; these 41,200 cal/mole −6.0 units (eu), respectively. Parabolic constants 550°– 700°C given by negative value when corrected formation vacancies leads 1.5 diffusion. Theoretical considerations suggest that latter term should have 1.7–3.3 eu. good agreement between theoretical experimental entropies suggests diffusion occurring largely through lattice oxide not grain boundaries, least time region which analyses were made.A comparison present older shows large variation constants. These variations impurities increasing concentration ion vacancies.