University of Hertfordshire

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Original languageEnglish
Number of pages7
Pages (from-to)677-683
JournalMaterials Science and Engineering A
Journal publication date1 Dec 1989
Volume120-121
Issue2
Publication statusPublished - 1 Dec 1989

Abstract

Two aluminium-chromium ferritic steels were exposed to simulated coal gasifier atmospheres for times of up to 900 h at 723 K. High-resolution analytical transmission electron microscopy was used to study the development of the corrosion product films as a function of alloy composition and time. The effect of pre-oxidation prior to exposure to these atmospheres was also investigated. An oxide film with a spinel structure was formed initially, and after 15 min a chromium-rich thiospinel formed as an outer layer. In the case of Fecralloy, with continued exposure, aluminium enrichment of the oxide restricted further growth of the thiospinel, and pre-oxidation leading to the formation of an aluminium-rich spinel was shown to inhibit sulphide (thiospinel) formation. Fecralloy was shown to provide long-term protection despite the early formation of sulphides

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