Metal dusting on an alumina forming Ni-base alloy
2006 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 48, no 7, 1679-1695 p.Article in journal (Refereed) Published
A high-performance commercial alumina-forming Ni-base alloy was studied after a 2 years field exposure at 540 degrees C in a methanol plant with a gas composition of 10-20%CO and 20-40%H2O, with some CO2 and the remainder H-2. The same material was also used in laboratory studies performed at 650 degrees C Using a gas mixture With higher CO and lower H-2,O content: 50%CO + 3%H2O + 47H(2) (carbon activity a(c) = 39). Post-exposure metallographic examinations together with thermodynamic calculations were used to identify and describe the metal dusting processes. A growth mechanism for metal dusting in nickel base alloys, which is independent of metal bulk diffusion, is identified. The process involves it separation of the carbon-saturated metal into a network of discontinuous precipitated carbides and a depleted Ni-austenite matrix followed by selective oxidation of the carbide network. The corrosion product consists of Cr-depleted Ni-particles, Cr-rich oxides and free carbon. The estimated metal dusting corrosion rate in the field exposure was 20-25 mu m/year. based on metallography and it was correlated to a theoretical model based on boundary diffusion processes.
Place, publisher, year, edition, pages
2006. Vol. 48, no 7, 1679-1695 p.
metal dusting, carburization, oxidation, synthesis gas, Ni-base alloy, alumina-formers, discontinuous precipitation, kinetics, diffusion, micro-cracks, corrosion, carburization, mechanisms, kinetics, iron
IdentifiersURN: urn:nbn:se:kth:diva-15836ISI: 000238926800007OAI: oai:DiVA.org:kth-15836DiVA: diva2:333878
QC 201005252010-08-052010-08-052010-08-25Bibliographically approved