Abstract
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°C to 900°C in 10−2 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 ternaryelement 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 effect. 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°C. It was found that for Al to be effective, a sufficient amount of the spinel, Al0.55Mo2S4, had to form within the inner portion of the scale.
Similar content being viewed by others
References
W. T. Baker, R. A. Perkins, and J. Van Liere,Mat. Perform. 24, 9 (1985).
B. Gleeson, D. L. Douglass, and F. Gesmundo,Oxid. Met. 31, 209 (1989).
B. Gleeson, D. L. Douglass, and F. Gesmundo,Oxid. Met. 33, 425 (1990).
M. F. Chen and D. L. Douglass,Oxid. Met. 32, 185 (1989).
M. F. Chen, D. L. Douglass, and F. Gesmundo,Oxid. Met. 31, 237 (1989).
R. V. Carter, D. L. Douglass, and F. Gesmundo,Oxid. Met. 31, 341 (1989).
Ge Wang, R. V. Carter, and D. L. Douglass,Oxid. Met. 32, 273 (1989).
V. V. Burnashova, P. K. Starodub, and G. B. Stoganov,Rus. Metall. 4, 189 (1977).
B. N. Das and P. A. Bock,Trans. Met. Soc, AIME 218, 733 (1960).
T. Rosenqvist,J. Iron Steel Inst. 176, 3 (1954).
S. R. Shatynski,Oxid. Met. 11, 307 (1977).
G. Southwell and D. J. Young,Oxid. Met. in press (1990).
M. Perez and J. P. Larpin,Oxid. Met. 24, 9 (1985).
K. Nishida, T. Narita, T. Tani, and G. Sasaki,Oxid. Met. 14, 65 (1980).
G. Habenbach, P. H. Courty, and B. Delmon,J. Catal. 31, 264 (1973).
A. L. Farragher and P. Cossee,Catal. Proc. Int. Congr. 5th 2, 1301 (1973).
B. S. Lee and R. A. Rapp,J. Electrochem. Soc. 131, 2998 (1984).
M. F. Chen and D. L. Douglass,Oxid. Met. 33, 103 (1990).
Ge Wang and D. L. Douglass,Oxid. Met. in press (1990).
J. M. Vandenburg and D. Brasen,J. Solid State Chem. 14, 203 (1975).
JANAF Thermochemical Tables, Third Edition, 1985 supplement, fromJ. Phys. Chem. Ref. Data,14, (1985).
H. Hindham and D. P. Whittle,Oxid. Met. 18, 245 (1982).
F. H. Stott and G. C. Wood,Mat. Sci. Tech. 4, 1072 (1988).
D. P. Whittle, Y. Shida, G. C. Wood, F. H. Stott, and B. D. Bastow,Philos. Mag. A46, 931 (1982).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gleeson, B., Douglass, D.L. & Gesmundo, F. The sulfidation behavior of Co-Mo alloys containing various ternary additions. Oxid Met 34, 123–150 (1990). https://doi.org/10.1007/BF00664342
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00664342