Abstract
The oxidation behavior of the nimonic alloy PE16 in carbon dioxide has been examined, at 700–800° C, for periods up to 10,250 hr duration. At all temperatures the oxidation kinetics were pseudoparabolic. The chromium-rich and titanium-bearing oxide scale was adherent, except at 800° C, when ∼10% spalled. Intergranular oxidation beneath the outer scale resulted in the formation of alumina and to a lesser depth, titanium oxide. The penetration increased parabolically with time and also with temperature, the activation energy being 50 kcal/mole. After oxidation at all temperatures the carbon profiles across the oxidized alloys were determined by nuclear microprobe analysis and indicated three distinct regions. From the gas interface carbon was picked up increasingly in the oxide scale, with a peak concentration (0.1–0.34 wt. %) at the oxide-alloy interface. The carbon level then fell sharply and to the depth of the titanium-bearing intergranular oxide the alloy was decarburized. At this juncture carbon had entered the alloy to a maximum concentration of 0.23–0.50 wt. % and a depth which increased both with temperature and exposure. Carburization is attributed to a crevice corrosion mechanism.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.