Metal dusting behaviour of several nickel- and cobalt-base alloys in CO-H2-H2O atmosphere / Q. Wu in Materials and corrosion, Vol. 62 N° 6 (Juin 2011)  

Metal dusting behaviour of several nickel- and cobalt-base alloys in CO-H2-H2O atmosphere [texte imprimé] / Q. Wu, Auteur ; J. Zhang, Auteur ; D. J. Young, Auteur . - 2011 . - pp. 521–530.
Génie Mécanique
Langues : Anglais (eng)
in Materials and corrosion > Vol. 62 N° 6 (Juin 2011) . - pp. 521–530

Mots-clés :	Carburization Cobalt Graphite Iron Metal dusting Nickel
Index. décimale :	620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux
Résumé :	The metal dusting behaviour of total 11 nickel- and cobalt-base alloys at 680 °C in a gas of 68%CO[BOND]31%H2[BOND]1%H2O (aC = 19.0, equation image = 5.4 × 10−25  atm) was investigated. All samples were electropolished and reacted in a thermal cycling apparatus. On the basis of their reaction kinetics, these alloys can be classified into three groups: the first, with rapid carbon uptake and significant metal wastage, consists of alloys of relatively high iron content (AC 66, 800H and NS-163); the second, with intermediate rates, consists of some Co-base alloys (HAYNES 188, HAYNES 25 and ULTIMET) and the third, with very low reaction rates, consists of nickel-base alloys with high chromium levels (601, HAYNES HR 160, 230, G-35 and EN 105). An external chromia scale protected group 3 alloys from carburization and dusting. However, this protective scale was damaged and not rehealed for group 1 and group 2 alloys, allowing carbon attack. In all cases, coke deposited on the surface with two typical morphologies: filaments and graphite particle clusters. Subsurface spinel formation in high iron-content alloys led to rapid dusting due to the significant volume expansion. Alloy carbon permeability was calculated from a simple law of mixtures, and shown to correlate reasonably well with initial dusting rate except for one cobalt-base alloy in which iron spinel formation was significant.
DEWEY :	620.1
ISSN :	0947-5117
En ligne :	http://onlinelibrary.wiley.com/doi/10.1002/maco.201005863/abstract