ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The oxidation mechanism of the T91 martensitic steel in oxygen-saturated Pb-Bi eutecticat 470°C has been investigated to develop a long term predictive model of the steel oxidationkinetic. This work is performed in the frame of life duration studies carried out for the MEGAPIEspallation module demonstrator dedicated to the feasibility demonstration of an hybrid reactor.Our scientific approach has been based on an experimental characterization of the oxide scales andof the T91 steel oxidation kinetics. From these experimental results, an oxidation mechanism hasbeen elaborated and then simulated.The oxide scale formed at the T91 surface has a duplex structure, constituted of an externalmagnetite scale and an internal Fe-Cr spinel scale. A scale growth mechanism has been proposed:the magnetite scale growth seems to be limited by the iron lattice diffusion inside the duplex oxidescale. At the same time, a self-regulation mechanism seems to govern the Fe-Cr spinel scale growth.This mechanism consists of a non-limiting oxygen diffusion step, which is carried out, across theoxide scale, inside liquid lead nano-channels and a limiting iron oxide lattice diffusion step.Considering the proposed oxidation mechanism, a simulation of the growth of the two oxides scaleshas been carried out and compared to the experimental oxidation kinetics. The excellent agreementbetween the experimental results and the simulations supports to accept the proposed mechanism,leading to prediction of kinetics for long oxidation durations
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.595-598.519.pdf
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