The sulfidation behavior of Co-Mo alloys containing various ternary additions. [55Co-20Mo-25X (X is Al, Cr, Mn, or Ti)]

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Oxidation of Metals; (United States)

DOI:https://doi.org/10.1007/BF00664342· OSTI ID:5471871

Gleeson, B; Douglass, D L ^[1]; Gesmundo, F ^[2]

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1. Univ. of California, Los Angeles (USA)
2. Universita di Genova (Italy)

The sulfidation behavior of Co-Mo-X alloys, where X is Al, Cr, Mn, or Ti, has been studied over the temperature range 600 or 700{degree}C to 900{degree}C in 10{sup {minus}2} atm. sulfur vapor to determine the effectiveness of the various ternary elements at reducing the sulfidation rate relative to Co-Mo alloys. For comparative purposes, each ternary alloy contained a constant atomic proportion (i.e., 55Co, 20Mo, and 25X). All of the alloys were multiphase, and sulfidized to form complex, multilayered scales. The scales usually consisted of an outer layer of cobalt sulfide, an intermediate layer that contained primarily the ternary-element sulfide, and an inner layer which was heterophasic. Usually, each phase within the multiphase alloy sulfidized independently of one another. In the region of the alloy/scale interface there was often a narrow band of fine porosity (transitional band) together with fine precipitates that separated the inner sulfide from the base alloy. It was found that Al and Cr improved the sulfidation resistance of the Co-Mo binary alloy, whereas Mn had the opposite effects. The Ti-containing alloy underwent a mixed sulfidation/oxidation process, so that its kinetics were inapplicable. Aluminum was found to exert the most beneficial effect. The sulfidation behavior of Co-Mo-Al alloys containing a range of Al concentrations was studied at both 700 and 900{degree}C. It was found that for Al to be effective, a sufficient amount of the spinel, Al{sub 0.55}Mo{sub 2}S{sub 4}, had to form within the inner portion of the scale.

• OSTI ID: 5471871
• Journal Information: Oxidation of Metals; (United States), Journal Name: Oxidation of Metals; (United States) Vol. 34:1-2; ISSN 0030-770X; ISSN OXMEA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALKALINE EARTH METAL COMPOUNDS
ALLOY SYSTEMS
ALLOYS
ALUMINIUM
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM
CHROMIUM ALLOYS
COBALT ALLOYS
COBALT BASE ALLOYS
COBALT COMPOUNDS
COBALT SULFIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIAGRAMS
DIFFRACTION
ELEMENTS
HIGH TEMPERATURE
INTERFACES
KINETICS
LAYERS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MANGANESE
MANGANESE ALLOYS
METALLURGICAL EFFECTS
METALS
MICROSTRUCTURE
MINERALS
MOLYBDENUM ALLOYS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE DIAGRAMS
POROSITY
REACTION KINETICS
SCALING
SCATTERING
SPECTROSCOPY
SPINELS
SULFIDATION
SULFIDES
SULFUR COMPOUNDS
TERNARY ALLOY SYSTEMS
TITANIUM
TITANIUM ALLOYS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY