Effect of surface-applied reactive elements on the high-temperature oxidation of chromium-containing alloys
It is well known that the addition of reactive metals, such as Y, Ce, La, etc., or fine dispersions of their oxides, to alloys containing Cr has considerable beneficial effects on the development, growth and mechanical stability of the oxide scales formed at high temperatures. In order to further investigate the cause of these effects, this study is concerned with the influence of the reactive metals and/or their oxides when they are present only on the alloy surfaces prior to the oxidation at 1000 and 1100/sup 0/C in 1 atm. O/sub 2/. Three binary alloys were used: Co-15 wt%Cr, a non-Cr/sub 2/O/sub 3/ former which will develop the Cr/sub 2/O/sub 3/ scale with reactive metal oxide additions to the alloy; Co-25wt%Cr, a borderline Cr/sub 2/O/sub 3/ former; and Ni-25wt%Cr, a good Cr/sub 2/O/sub 3/ former. The oxides of Ca, Ce, La, Y, Hf, and Zr were applied as a thin surface coating through the application and decomposition of their aqueous nitrate salts. Y and La were also introduced in their metallic form by ion-implantation. Unlike the case where the reactive elements are present in the alloy, none of the surface-applied oxides promoted a continuous Cr/sub 2/O/sub 3/ external scale with alloys that are not already good Cr/sub 2/O/sub 3/ formers. Surface-applied CeO/sub 2/, Y/sub 2/O/sub 3/, and La/sub 2/O/sub 3/ were particularly effective in reducing the growth rate of the Cr/sub 2/O/sub 3/ scale and improving the scale adhesion.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 7005595
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Effect of surface-applied reactive element oxide on the oxidation of binary alloys containing Cr
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Related Subjects
CALCIUM OXIDES
METALLURGICAL EFFECTS
CERIUM OXIDES
CHROMIUM ALLOYS
OXIDATION
PROTECTIVE COATINGS
CHROMIUM OXIDES
COBALT ALLOYS
HAFNIUM OXIDES
LANTHANUM ADDITIONS
LANTHANUM OXIDES
NICKEL ALLOYS
SURFACES
YTTRIUM ADDITIONS
YTTRIUM OXIDES
ZIRCONIUM OXIDES
VERY HIGH TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
CALCIUM COMPOUNDS
CERIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
COATINGS
HAFNIUM COMPOUNDS
LANTHANUM ALLOYS
LANTHANUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
RARE EARTH COMPOUNDS
REFRACTORY METAL COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM ALLOYS
YTTRIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
360105* - Metals & Alloys- Corrosion & Erosion
360205 - Ceramics
Cermets
& Refractories- Corrosion & Erosion