Oxide scale adhesion and impurity segregation at the scale/metal interface

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Oxidation of Metals; (United States)

DOI:https://doi.org/10.1007/BF00665658· OSTI ID:6950794

Hou, P Y ^[1]; Stringer, J ^[2]

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1. Lawrence Berkeley Lab., CA (United States)
2. 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), Journal Name: Oxidation of Metals; (United States) Vol. 38:5-6; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ADHESION
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
ELEMENTS
INTERFACES
IRON ALLOYS
IRON BASE ALLOYS
MICROSCOPY
NONMETALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
SCALING
SEGREGATION
SULFUR
TRANSITION ELEMENT COMPOUNDS