Oxygen-18 and deuterium profiling in thick films on Fe-9% Cr alloys by 3 MeV nuclear microprobe

Pritchard, A.M.; Hartley, N. E. W.; Singleton, J. F.; Truswell, A.E.

doi:10.1016/0010-938x(80)90105-5

Cited by 25 publications

(8 citation statements)

References 5 publications

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“…This structure, illustrated in Fig. 2, is typical of dilute Fe-Cr alloys and has been observed by others after exposure to CO 2 [5,13] and CO 2 -H 2 O [1,14] in the temperature range 550-900°C.…”

Section: Formation Of External Oxide Scalessupporting

confidence: 74%

Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Gheno¹,

Monceau²,

Zhang³

et al. 2011

Corrosion Science

154

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Section: Formation Of External Oxide Scalessupporting

confidence: 74%

Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Gheno¹,

Monceau²,

Zhang³

et al. 2011

Corrosion Science

154

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“…7). Many investigations of duplex growth using inert markers (8,10,12) show that the boundary between the layers corresponds to the position of the original metal surface, which may indicate that the inner layer grows from the original metaloxide interface by inward oxygen diffusion, while the outer layer grows towards the oxide-gas interface by outward diffusion of iron cations. This is in agreement with EDS and mapping scans taken from cross-sections through the oxide layer, which revealed that the alloying elements present in the steel are only found in the inner layer.…”

Section: Isothermal Oxidationmentioning

confidence: 99%

“…Although extensive research has been conducted (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) to study the oxidation behaviour of steels under various atmospheres, theses studies have been generally carried out under isothermal conditions. However, during operation of the power generating plant the tubes are not strictly subjected to a constant temperature during their life in service.…”

Section: Introductionmentioning

confidence: 99%

Oxidación de aceros ferríticos con vapor de agua: cinética y microestructura

Ariztegui¹,

Gómez-Acebo²,

Castro³

2000

Bol. Soc. Esp. Ceram. Vidr.

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The ferritic 2.25Cr-1Mo steel has been subjected to isothermal and non-isothermal oxidation treatments in water steam at several temperatures ranging from 550 to 700 °C for up to 56 days. Under isothermal conditions this steel follows a parabolic oxidation kinetics, with an activation energy of 324 kJ mol -1 . This value corresponds to an apparent activation energy for the global process, which includes both outward diffusion of Fe cations and inward diffusion of oxygen. The oxidation products present in the oxide scales, which were characterised by X-ray diffraction and SEM, are in total agreement with the Fe-O phase diagram. Thus, magnetite is the most stable oxide at low temperatures and wustite starts to form above 570 °C. Further studies of the effect of cooling rate have shown that wustite formed at 700 °C transforms into magnetite during a slow cooling, whereas a rapid cooling inhibits this transformation to a certain extent. For non-isothermal oxidation treatments consisting of a holding period at 550 °C followed by a single or double 4 hours exposure at 700 °C, the oxidation process seems to occur in sequence, thus presenting an additive effect of the oxidation treatments carried out at each temperature. This effect was observed both, for the type of oxide grown, and for the kinetics of the process. Microscopic observations of the oxide scales formed after the various oxidation treatments revealed that the oxide scales are constituted by sublayers of distinct microstructure and chemical composition changing from their surface to the substrate interface. Keywords: Ferritic steel, isothermal and non-isothermal oxidation, kinetics, diffusion mechanism. Oxidación de aceros ferríticos con vapor de agua: cinética y microestructuraSe han realizado tratamientos de oxidación isotermos y no isotermos a un acero ferrítico 2,25Cr-1Mo en vapor de agua, a temperaturas comprendidas entre 550 y 700 °C y tiempos de hasta 56 días. En condiciones isotermas, este acero tiene una cinética de oxidación parabólica, con una energía de activación de 324 kJ mol -1 . Este valor corresponde a una energía de activación aparente del proceso global, que incluye tanto la difusión hacia el exterior de cationes de Fe, como la difusión de oxígeno hacia el interior. Los productos de oxidación presentes en la capa de óxido, caracterizados por difracción de rayos-X y SEM, están en total concordancia con el diagrama de fases del sistema Fe-O. La magnetita es el óxido más estable a bajas temperaturas, y la wustita comienza a formarse por encima de 570 °C. Estudiando el efecto de la velocidad de enfriamiento se ha comprobado que la wustita formada a 700 °C se transforma en magnetita en un enfriamiento lento, mientras que el enfriamiento rápido inhibe en parte esta transformación. En los tratamientos de oxidación no isoterma, consistentes en un periodo de mantenimiento a 550 °C seguido de exposición simple o doble a 700 °C, el proceso de oxidación parece producirse secuencialmente, presentando así un efecto aditivo de los tratamientos de oxidac...

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“…The outer oxide layer has been well known as Fe 3 O 4 and the inner layer consists of (Fe,Cr) 3 O 4 . Tracer studies have confirmed that the original metal surface corresponded to the outer-inner layer interface [15][16][17]. That means the outer and inner oxide layers develop simultaneously, and the outer layer grows by the outward diffusion of Fe cations, while the inner layer grows by the inward diffusion of oxygen [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Understanding the surface oxide evolution of T91 ferritic-martensitic steel in supercritical water through advanced characterization

2020

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The surface oxide scale formed on T91 steel after exposure to deaerated supercritical water (SCW) at 600 ºC for 100-1500 h are characterized in detail to reveal the oxide evolution over time. A triplex structure with outer, inner and internal oxide layers has been confirmed. The thickness of each oxide layer increases with the exposure time following the power law kinetics. The different oxide phases in each oxide layer are the results of the decreasing partial pressure of oxygen inwards the depth of oxide scale. The inner and internal oxide layers are not uniform in Fe and Cr contents. The internal oxide layer consists of Cr-rich oxide precipitates surrounded by metal matrix in the grain interior, which could be explained by the internal oxidation mechanism. After a further longtime exposure, a continuous thin Cr-rich spinel oxide layer is formed at the internal oxide layer-metal matrix interface, which is the result of transition from internal to external oxidation when the outward diffusion of Cr exceeds the inward diffusion of oxygen. The inner oxide layer consists of Cr-rich spinel oxide precipitates surrounded by Fe-rich spinel oxide. The formation of the inner oxide layer is the result of further oxidation of the internal oxide layer where the metal matrix in the grain interior is oxidized into Fe-rich spinel.

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Oxygen-18 and deuterium profiling in thick films on Fe-9% Cr alloys by 3 MeV nuclear microprobe

Cited by 25 publications

References 5 publications

Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Carburisation of ferritic Fe–Cr alloys by low carbon activity gases

Oxidación de aceros ferríticos con vapor de agua: cinética y microestructura

Understanding the surface oxide evolution of T91 ferritic-martensitic steel in supercritical water through advanced characterization

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