Effect of preoxidation of some Ni, Fe, and Co-base alloys on subsequent sulfidation at 982/sup 0/C in sulfur vapor
The effect of preoxidation was studied on the subsequent sulfidation in sulfur vapor at a pressure of 0.1 atm at 982/sup 0/C on numerous iron, nickel, and cobalt-base alloys which were either chromia or alumina formers. In general, alumina films were much more protective than chromia films, but the efficacy of preoxidation in reducing sulfidation rates depended more upon perfection of the films and whether cracking and/or spalling occurred. Increasing oxide-film thickness had a beneficial effect until either penetration of the films by sulfur or cracking occurred, after which sulfidation rates were sometimes greater than for nonpreoxidized samples. The enhanced sulfidation rates are attributed to sulfidation of a solute-depleted substrate, the solute having been selectively removed by oxide formation. One alloy, MA 956, containing 0.5 Y/sub 2/O/sub 3/ as fine dispersions which normally provide spalling resistance, still exhibited extensive cracking and spalling of the oxide and was not much better than alloys without dispersoids or reactive-metal additions. The use of preoxidation to reduce sulfidation rates is not viable under the extreme conditions used. Preoxidation is conceptually a good method for inhibiting sulfidation at lower temperatures and much lower sulfur pressures.
- Research Organization:
- Scanning Electron Analysis Labs., Inc., Los Angeles, CA (USA)
- OSTI ID:
- 6163847
- Journal Information:
- Oxid. Met.; (United States), Journal Name: Oxid. Met.; (United States) Vol. 30:5-6; ISSN OXMEA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effect of preoxidation on the corrosion of some alloys in coal chars and sulfur vapor. Final report
High-temperature corrosion and mechanical properties of protective scales on incoloy 800H: The influence of preoxidation and ion implantation
Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COAL GASIFICATION
COBALT ALLOYS
COBALT BASE ALLOYS
COHERENT SCATTERING
CORROSION PROTECTION
CORROSIVE EFFECTS
DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
FILMS
FLUIDS
GASES
GASIFICATION
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INCOLOY ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MICROSCOPY
NICKEL ALLOYS
NICKEL BASE ALLOYS
NONMETALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PASSIVATION
SCANNING ELECTRON MICROSCOPY
SCATTERING
SPECTRA
SULFIDATION
SULFIDES
SULFUR
SULFUR COMPOUNDS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
VAPORS
X-RAY DIFFRACTION
X-RAY SPECTRA