Browsing by Author "Shin, Aya"
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Item Open Access Assessment of corrosive attack of Fe9Cr1Mo alloys in pressurised CO2 for prediction of breakaway oxidation(Elsevier, 2023-07-27) Gong, Yilun; Gill, Simon P. A.; Yan, Sabrina; Higginson, Rebecca; Sumner, Joy; Simms, Nigel J.; Larsson, Henrik; Shin, Aya; Pearson, Jonathan M.; Young, David J.; Atkinson, Colin; Cocks, Alan C. F.; Reed, Roger C.To provide clarity on the poorly-understood mechanism of breakaway oxidation, corrosion of Fe9Cr1Mo steel in pressurised CO is quantified and modelled. The temperature range 400–640 , relevant to nuclear power plants, is emphasised. Attack is in the form of combined oxide scale growth and internal carburisation of the metal. Carbon activity in the metal at its surface exhibits a strong time dependence consistent with the kinetically-limited transport of carbon due to the slow Boudouard reaction. Breakaway is associated with the approach to saturation of the steel with respect to carbon. Diffusion modelling agrees well with steel carbide precipitation observations.Item Open Access Kinetics of duplex oxide growth on 9Cr steels exposed in CO2: application of dimensional metrology(Springer, 2017-04-05) Sumner, Joy; Simms, Nigel; Shin, Aya; Pearson, JonathanInvestigations into potentially extending the lives of UK advanced gas-cooled reactors have highlighted the need for improved understanding of the long-term oxidation and carburisation of 9Cr ferritic steels. These steels were used in evaporators and primary superheaters and as these are to be used beyond their original design lives, it is necessary to ensure that these degradation routes remain within acceptable levels. A dimensional metrology technique has been applied to archived autoclave samples to measure such damage. These samples had previously been exposed to a range of temperatures, pressures and gas chemistries representative of those experienced by 9Cr steels in CO2-rich AGR gases. Earlier sample assessments had focused on weight change measurements, but the dimensional technique enables measurement of duplex oxide thicknesses around samples and the extraction of related data from longer exposure times. These data also support estimation of the extent of both carbon and oxygen uptake.