Abstract

Isothermal oxidation at high temperature of a nickel-chromium alloy in water vapor-rich air. Part 1: Mass gain rates and kinetic constants

Author(s): Lionel Aranda, Patrice Berthod

AbinaryNi-30Cr alloy, known for its chromia-forming behaviour, previously elaborated by foundry and tested in oxidation at temperatures ranging from 1000 and 1300°C in dry air and in moderately water vapour-enriched air, has been here subjected to hot oxidation at the same temperatures (1000, 1100, 1200 and 1300°C) for 48 hours in a very humidified air, with thermogravimetric measurements. The exploitation of the mass gain files was carried out following several methods. Since chromia volatilization was particularly fast (at 1300°C notably) the treatment was done by applying the {m × dm/ dt = Kp – m × Kv}–method. The values of the parabolic constant Kp and of the chromia volatilization constant Kv were specified together. If they both logically increase with temperature the variation with the air humidity rate was less evident. These present kinetic results will be strengthened by metallographic characterization in a second part of this work, for a better interpretation of the effect of water vapor in such high concentration.