Oxidation Behaviour of IN-738 LC Superalloys in the Presence of Ionic Salts at 1173 K

M. Misbahul Amin*

Department of Chemistry, Faculty of Science & Technology, University College of Science & Technology Malaysia, Mengabang Telipot, 21030 Kuala Terengganu, Malasya.

Received 14 July 2003; accepted in revised form 11 November 2003

Abstract

Oxidation of the alloy having nominal composition Ni-16Cr-8.5Co(wt.%) was studied in the presence of KCl and K₂CO₃ at 1173 K in air. Chemical composition of oxide scales and scale morphologies were determined by means of X-ray diffraction analysis and scanning electron microscopic studies. The oxide scales of KCl- and K₂CO₃- coated alloys showed complex microstructures and compositions. This behaviour was ascribed to the release of volatile metallic chlorides, evolution of CO/CO₂ gas as well as formation of fluxing products. The high temperature oxidation resistance is not only related to the nature of the passive film but is also strongly dependent on the salt environments and the structure of alloy.

Keywords: Oxidation, IN-738 LC Alloy, KCl, K₂CO₃.

Texto completo disponível apenas em PDF.

Full text only in PDF format.

References

1. F.J. Pennisi, D.K. Gupta, Thin Solid Films 84 (1981) 49.        [ Links ]

2. T.N. Rhys-Jone (Protective Oxide Scales on Superalloys and Coatings Used in Gas Turbine Blades and Vanes Applications), Mat.Sci. 4 (1988) 421.        [ Links ]

3. D.A. Shores, Corrosion 13 (1975) 434.        [ Links ]

4. D.K. Gupta, D.S. Duvall, “Superalloys 1984”, Proc. 5^th Intnl. Symp. on Superalloy, Seven Springs, Champion, PA, Oct. 7-11,1984, p. 71.        [ Links ]

5. C.A.C. Sequeira, M.G. Hocking, J. Appl. Chem. 8 (1978) 152.        [ Links ]

6. C.G. McGreath, Mat. Sci. Eng. 88 (1987) 303.        [ Links ]

7. B.L. Tremillon, G. Picard, Proc. 1^st Intnl. Symp. on Molten Salt Chemistry and Technology, Y. It, Ed. Kyoto, 1978, p. 1246.        [ Links ]

8. J.R. Vargas, “Metallurgical 80”, Conf. Proc., San Diego, C. A.,Vol. II, J.N. Zemel (Ed.), Elsevier Sequoia, Lausanne, 1980, p. 407.        [ Links ]

9.G. Picard, H.M. Lefebure, B.L. Tremillon, Proc. 5^th Intnl. Conf. on Molten Salts, Las Vegas, Oct. 13-18, 1985, p. 428.        [ Links ]

10. Thermal Convention Loop Corrosion Tests of 31655 and IN-800 in Molten Salts, Sandia Report 81-8210, 1982, p. 654.        [ Links ]

11. L.V. Shelton, R.S. Carlton, J. Eng. Gas Turbine Power, Trans. ASME 106 (1984) 819.        [ Links ]

12. A.J.B. Cutler, Mat. Sci. Technol. 3 (1987) 512.        [ Links ]

13. Y. Shinata, Y. Nishi, “Hot Corrosion of Ni-20Cr base alloys induced by Na₂SO₄, NaCl mixtures”, Proc. JIMIS-3, High Temp. Corrosion JIM Supplement, 1983, p. 386.        [ Links ]

14. W.L. Fielder, C.A. Stearns, F.J. Kohl, “Reactions of NaCl with gaseous SO₃, SO₂, and O₂”, NASA-TM 83423, NASA Scientific and Technical Information Branch, Washington D.C., 1983, p. 1553.        [ Links ]

15. F.J. Kohl, C.A. Stearns, G.C. Fryburg, “The role of NaCl in flame chemistry, in the deposition process, and its reaction with protective oxides”, Proc. 4^th US/UK Navy Conf. on Gas Turbine Materials in a Marine Environment, Vol. II, U.S. Naval Sea Command, Annapolis, MD, 1979, p. 565.        [ Links ]

16. S.Y. Liu, C.L. Lee, C.H. Kao, T.P. Perng, Corrosion 56 (2000) 338.        [ Links ]

17. A. Dais, V.F. Cunha Lins, Corros. Sci. 40 (1998) 273.        [ Links ]

18. P. Hancock, Corros. Sci. 22 (1982) 51.        [ Links ]

19. M.M. Amin, Bull. Chem. Soc. Ethiop. 7 (1993) 94.        [ Links ]

20. M. Stratmann, K. Hoffmann, Corros.Sci. 29 (1989) 1329.        [ Links ]

21. O.F. Devereux, K.Y. Kim, K.S. Yeum (Reactions at the Corroding Nickel Electrode in Molten Sodium Carbonate under CO/CO₂ Atmosphere), Corros. Sci. 23 (1983) 216.        [ Links ]

22. M. Amin (Hot Corrosion Behaviour of Inconel-600Alloy in Presence of NaCl and Na₂CO₃ at 850 ^oC), Prakt. Metallogr. 30 (1993 ) 240.        [ Links ]

23. M.M. Amin (Effect of Some Salt Coatings on the High Temperature Oxidation of Nimonic-80A Alloy at 1173 K), Thin Solid Films 299 (1997) 3.        [ Links ]

24 P.J. Smith, W.W. Smeltzer, Oxid. Met. 28 (1987) 291.        [ Links ]

25. M.M. Amin (The CsCl- and CsNO3-induced High Temperature Oxidation of Nimonic-90 Alloy at 1123 K), Appl. Surf. Sci. 115 (1996) 358.        [ Links ]

26. A.U. Malik, M.M. Amin, S. Ahmed, Transact. Jpn. Inst. Met. 25 (1984) 172.        [ Links ]

27. T.Kr. Aune, O. Lunder, K. Nisancioglu, Microstructural Science 17 (1988) 232.        [ Links ]

28. M.C. Ball, A.H. Norbury, “Physical Data for Inorganic Chemists”, Longman Group Ltd., (1974).        [ Links ]

29. P.L. Daniel, R.A. Rapp (Advances in Corrosion Science and Technology), Corros. Sci. 5 (1976) 55.        [ Links ]

* Corresponding author. E-mail: misbah@kustem.edu.my; mmamin@lycos.com.