The Kinetics of Oxidation of High Purity Nickel

Abstract

The effect of time, temperature, and surface pretreatment on rate of oxidation of high purity nickel is studied for the temperature range of 400~176 using a vacuum microbalance technique. The data are compared to previous studies in the literature and with other metals. Oxidation data are interpreted in terms of the parabolic rate law and classical theory of diffusion.Large deviations from the parabolic rate law are found to occur during the initial stages of reaction and smaller deviations over long periods of time, especially at low temperatures. However, reasonable values of heat and entropy of activation for the over-all reaction can be calculated; these are 41,200 cal/mole and -6.0 entropy units (eu), respectively. Parabolic rate law constants over the temperature range of 550 ~ 700~ are given by A = 3.8 X l~4e-41'~~The negative value for entropy of activation for the over-all reaction when corrected for entropy of formation of the vacancies leads to a value of 1.5 for entropy of activation for diffusion. Theoretical considerations suggest that the latter term should have a value of 1.7-3.3 eu. The good agreement between theoretical and experimental entropies of activation suggests that diffusion is occurring largely through the lattice of nickel oxide and not at grain boundaries, at least for the temperature and time region over which analyses were made.A comparison of present data with older studies in the literature shows a large variation in parabolic rate law constants. These variations are interpreted in terms of impurities increasing the concentration of nickel ion vacancies, KINETICS OF OXIDATION OF NICKEL 131

Frictional Characteristics of Cobalt, Nickel, and Iron as Influenced by Their Surface Oxide Films

“…P resent ed as an American Society of Lubrication En gineers paper at the Lu brication Con ference held in Pittsbu rgh, Pennsylvania, Octob er [16][17][18]1962.…”

Comparative Oxidation Kinetics of a NiPtTi High Temperature Shape Memory Alloy

“…It is seen that Ti rates intersect those of Ni at lower temperature, around 600°C, but exceed them substantially above 800°C. The other Ni studies shown, from Gulbransen and Andrew [22], Progar and Lewis [23], and Atkinson et al [24], bound the Kofstad values in some proximity, but exhibit noticeable offsets. There is thus some uncertainty as to which data set might represent the best comparison for baseline NiO growth kinetics.…”

“…N.A. [9] Ni (G) 1.63 9 10 6 4.52 9 10 -4 167 550-700 6 0.99 [22] Ni (P) 1.38 9 10 6 3.84 9 10 -4 174 815-1370 1-2 1.00 [23] Ni (A) 5.22 9 10 6 1.45 9 10 -3 154 500-800 109 0.98 [24] agreement with overall TiO 2 control. The diversion of the 500°C Ni49Ti data and the other Ni-Ti alloys at 135-150 kJ/mol suggests that there may be a common factor causing this deviation.…”

Comparative study of transport properties relevant to a textured sol-gel PZT coating on Ni substrate

“…Although the kinetics of nickel oxidation have been widely studied [17][18], its interaction with PZT films has not been reported. In this work, PZT thin films were prepared by sol gel on two types of nickel, untextured and (200) textured foil, and the evolution of nickel oxide was Sol A + 10% w/v of PZT seeds with particle size lower than 100 nm [19], three layers, pre-annealed at 400 ~ for 10 seconds followed by rapid heating to 700 ~ annealed for 30 min, fast cooling.…”