Abstract
Previous work showed that MoSi2 diffusion coatings formed by a NaF-activated pack cementation process did not pest. A Na−Al-oxide by-product layer resulting from the NaF activator formed a Na-silicate layer to passivate MoSi2. Superficial NaF layers were then used to prevent the pesting of MoSi2 diffusion coating that were otherwise susceptible to pest disintegration. In this study, the use of superficial alkali-salt layers to prevent the accelerated oxidation of bulk MoSi2 at 500°C is investigated more broadly. The application of Na-halide, KF, LiF, Na2B4O7, or Na-silicate layers prior to oxidation prevented accelerated oxidation and pesting for at least 2000 hr at 500°C in air. The formation of a fast-growing, Na-silicate layer passivates MoSi2. The MoO3 that forms during oxidation absorbs sodium by intercolation to form stable Na-molybdate precipitates. Na2B4O7, Na-silicate, LiF, and KF prevented accelerated oxidation at 500°C by a similar mechanism. The application of alkali-halide salts is a simple, effective solution to prevent the accelerated oxidation and pesting of MoSi2.
Similar content being viewed by others
References
J. Schliching,High Temp. Pressures 10, 241 (1978).
R. R. Giler,Met. Eng. Quart. Nov., 452 (1973).
G. Meier, N. Birks, F. S. Pettit, R. A. Perkins, and H. J. Grabke, inFirst International Symposium on Structural Intermetallics, R. Darolia, J. J. Lewandowski, C. T. Liu, P. L. Martin, D. B. Miracle, and M. V. Nathal, eds. (TMS, 1993), p. 861.
D. A. Berztiss, R. R. Cerchiara, E. A. Gulbransen, F. S. Pettit, and G. H. Meier,Mater. Sci. Eng. A155, 165 (1992).
J. R. Berkowitz-Mattuck, P. E. Blackburn, and E. J. Felton,Trans. Met. Soc. AIME 233, 1093 (1965).
J. R. Berkowitz-Mattuck, M. Rossetti, and D. W. Lee,Met. Trans. 1, 479 (1970).
J. J. Petrovic,MRS Bull. 18(7), 35 (1993).
A. K. Vasudevan and J. J. Petrovic,Mater. Sci. Eng. A155, 1 (1992).
R. M. Aikin, Jr., inFirst International Symposium on Structural Intermetallics, R. Darolia, J. J. Lewandowski, C. T. Liu, P. L. Martin, D. B. Miracle and M. V. Nathal, eds. (TMS, 1993), p. 791.
T. C. Chou and T. G. Nieh,JOM 45(12), 15 (1993).
T. C. Chou and T. G. Nieh,J. Mater. Res. 8, 214 (1993).
T. C. Chou and T. G. Nieh,J. Mater. Res. 8, 1605 (1993).
P. J. Meschter,Met. Trans. 23A, 1763 (1992).
R. W. Bartlett, J. W. McCamont, and P. R. Page,J. Am. Ceram. Soc. 48, 551 (1965).
J. H. Westbrook and D. L. Wood,J. Nucl. Mater. 12, 208 (1964).
C. G. McKamey, P. F. Tortorelli, J. H. Devan, and C. A. Carmichael,J. Mater. Res. 7, 2747 (1992).
E. W. Lee, J. Cook, A. Khan, R. Mahapatra, and J. Waldman,JOM 43 (5), 54 (1991).
J. Cook, A. Khan, E. Lee, and R. Mahapatra,Mater. Sci. Eng. A155, 183 (1992).
W. O. Soboyejo, K. T. Venkatesawara Rao, S. M. L. Sastry, and R. O. Ritchie,Met. Trans. 24A, 585 (1992).
J. J. Petrovic and R. E. Honnell,Ceram. Eng. Sci. Proc. 11, 734 (1990).
E. Fitzer,Warmfeste und Korrosionsbeständige Sinterwerkstoffe 2, Plansee Seminar, June 19–23, 1955, F. Benesovsky, ed. (Springer-Verlag, 1956), p. 56.
E. Fitzer and J. Schwab,Metall. 9, 1062 (1955).
E. Fitzer, H. Herbst, and J. Schlichting,Werkst. Korros. 24, 274 (1973).
D. M. Shah, A. Berczik, D. L. Anton, and R. Hecht,Mater. Sci. Eng. A155, 45 (1992).
E. Fitzer and D. Kehr,Thin Solid Films 39, 55 (1976).
A. Mueller, G. Wang, R. A. Rapp and E. L. Courtright,J. Electrochem. Soc. 139, 1266 (1992).
A. Mueller, G. Wang, R. A. Rapp, E. L. Courtright, and T. A. Kircher,Mater. Sci. Eng. 115A 199 (1992).
E. Fitzer,Austrian Patent 200,806, Nov. 25, 1958.
E. Fitzer,German Patent 962,393, Apr. 18, 1957.
E. Fitzer,U.S. Patent 2,902,392, Sept. 1, 1959.
R. Bianco, M. A. Harper, and R. A. Rapp,JOM 43(11), 20 (1991).
T. A. Kircher and E. L. Courtright,Mater. Sci. Eng. A155, 67 (1992).
B. V. Cockeram, G. Wang, and R. A. Rapp,Werkst. Korros. 46, 207 (1995).
R. Watson, R. Mudway, and M. Sidoti,Ceram. Eng. Proc. 11, 1922 (1990).
J. F. Moulder, W. F. Stickle, P. E. Sobol and K. D. Bomben,Handbook of X-ray Photoelectron Spectroscopy (Perkin-Elmer Corp., Eden Prairie, MN, 1992).
R. S. Roth, J. P. Dennis and H. F. McMurdie, eds.,Phase Diagrams for Ceramists, Vol. VI (American Ceramic Society, Westerville, OH, 1987), p. 187.
B. Cockeram,Ph.D. dissertation, The Ohio State University 1994.
A. Rahmel and P. J. Spencer,Oxid. Met. 35, 53 (1991).
JANAF Thermodynamical Tables, 3rd ed., 1985 supplement, fromJ. Phys. Chem. Ref. Data 14 (1985).
L. B. Pankratz, J. M. Stuve, and N. A. Gokcen,U. S. Bur. Mines Bull. 677, 317 (1984).
P. Kofstad,High Temperature Corrosion (Elsevier, New York, 1988), 289, 416.
W. D. Kingery, H. K. Bowen, and D. R. Uhlmann,Introduction to Ceramics, 2nd ed. (Wiley, New York, 1975).
H. Scholze,Glass Nature, Structure, and Properties (Springer-Verlag, New York, 1990), pp. 297, 340.
E. W. Sucov,J. Am. Ceram. Soc. 46, 14 (1963).
A. F. Wells,Structural Inorganic Chemistry, 5th ed. (Clarendon-Oxford Science, Oxford, 1986), pp. 531, 572, 617.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Cockeram, B.V., Wang, G. & Rapp, R.A. Preventing the accelerated low-temperature oxidation of MoSi2 (pesting) by the application of superficial alkali-salt layers. Oxid Met 45, 77–108 (1996). https://doi.org/10.1007/BF01046821
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01046821