Oxide scale adhesion and impurity segregation at the scale/metal interface
- Lawrence Berkeley Lab., CA (United States)
- Electric Power Research Inst., Palo Alto, CA (United States)
The chemistry at scale/metal interfaces was studied using scanning Auger microscopy after removal of the scale in ultra-high vacuum using an in situ scratching technique. Al[sub 2]O[sub 3] and Cr[sub 2]O[sub 3] scales formed between 900[degrees]C and 1,100[degrees]C on Fe-18 wt.% Cr-5 wt.% Al and on Ni-25 wt.% Cr alloys, respectively, were investigated. The adhesion of these scales was determined qualitatively by way of micro-indentation and scratching on the surface oxide. All of the alumina scales fractured to the same degree to expose the metal surface, regardless of the oxidation temperature. The chromia-forming alloy on the other hand, developed more adherent scales at lower oxidation temperatures. About 20 at.% sulfur was found at the metal surface in all cases, and its presence was not only detected on interfacial voids, but also on areas where the scale was in contact with the alloy at temperature. Results from this study clearly demonstrated that sulfur as an alloying impurity does segregate to the scale/alloy interface. However, for alumina scales and chromia scales, the effect of this segregation on oxide adhesion is noticeably different.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6950794
- Journal Information:
- Oxidation of Metals; (United States), Vol. 38:5-6; ISSN 0030-770X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALLOYS
INTERFACES
SCALING
ALUMINIUM OXIDES
CHROMIUM OXIDES
ADHESION
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
IRON BASE ALLOYS
MICROSCOPY
OXIDATION
SEGREGATION
SULFUR
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
ELEMENTS
IRON ALLOYS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360105* - Metals & Alloys- Corrosion & Erosion