Abstract
The performance of gas turbines has been improved by the development of alloys with progressively increasing high-temperature capabilities. While both strength and corrosion resistance are important, the strength requirements have a higher priority, and alloy developments which led to higher strengths also had the effect of reducing the corrosion resistance, particularly with nickel-base alloys. The most important form of corrosion is the accelerated oxidation which takes place when the air or fuel is contaminated with certain impurities, of which alkali metal salts are the most important. This type of attack is generally known as ‘hot corrosion’. Two different forms of hot corrosion have been distinguished. Type I, which is present over a temperature range of about 800–950°C, and type II, which is present over the range 700–800°C. Both processes involve an incubation period, an initiation step, and a propagation stage. Most attention has been given to the propagation stage but, from a technical point of view, the initiation step is the most important process. Mechanisms suggested include the salt fluxing model, the electrochemical model, and the sulphidation–oxidation model. Both the practical and theoretical aspects of the problem will be reviewed.
Get full access to this article
View all access options for this article.
References
1.
D. Driver, D. W. Hall, and G. W. Meetham: in ‘The development of gas turbine materials’, (ed. G. W. Meetham), 1–30; 1981, London, Applied Science Publishers Ltd.
2.
J. E. Restall: in ‘High temperature corrosion of aerospace alloys’, (ed. J. Stringer et al. ), 12–29; 1973, Neuilly-sur-Seine, France, NATO Advisory Group for Aerospace Research and Development.
3.
R. F. Decker and C. T. Sims: in ‘The superalloys’, (ed. C. T. Sims and W. C. Hagel), 33–78; 1972, New York, John Wiley and Sons.
4.
R. A. Rapp: in ‘High temperature corrosion of aerospace alloys’, (ed. J. Stringer et al ), 147–153; 1973, Neuilly-sur-Seine, France, NATO Advisory Group for Aerospace Research and Development.
5.
J. H. Wood, T. R. Farrell, and R. G. Kunkel: ‘Protective cladding and coatings for utility gas turbines’, Final Report No. AP-3267, Project RP 1460–1, Electric Power Research Institute, Palo Alto, Cal., 1983.
6.
J. Stringer: ‘High temperature corrosion of aerospace alloys’, AGARDograph No. 200, NATO Advisory Group for Aerospace Research and Development, Neuilly-sur-Seine, 1975, p. 610.
7.
Proc. 1st US/UK Navy Conf. on ‘Gas turbine materials in a marine environment’, Hyattsville, Md, 1972.
8.
Proc. 2nd US/UK Navy Conf. on ‘Gas turbine materials in a marine environment’, Castine, Maine, 1974.
9.
Proc. 3rd US/UK Navy Conf. on ‘Gas turbine materials in a marine environment’, Bath, 1976.
10.
Proc. 4th US/UK Conf. on ‘Gas turbine materials in a marine environment’, Annapolis, Md, 1979, United States Naval Academy.
11.
J. E. Radway: ‘Corrosion and deposits from combustion gases’; 1985, Washington, DC, Hemisphere Publishing Corporation.
12.
R. W. Archdale: ‘The corrosion of gas turbine blades under marine operating conditions’, Report ISMET 2805 HR 558, Inter-Service Metallurgical Research Council Heat Resistant Metals Committee, 1961.
13.
J. F. G. Condé: in Proc. Conf. on ‘Naval materials: current and future problems’, Royal Naval Engineering College, Manadon, 1970.
14.
C. C. Smith, P. Dean, W. E. Laker, and D. Jones: ‘Examination of Nimonic 100 1st stage turbine blades ex engine CL.505 Mk 101A’, Bristol-Siddeley Engines Laboratory Report No. 452, Bristol, 1957.
15.
G. Llewellyn: in STP 421, ‘Hot corrosion problems associated with gas turbines’, 1; 1967, Philadelphia, Pa, American Society for Testing and Materials.
16.
STP 421, ‘Hot corrosion problems associated with gas turbines’; 1967, Philadelphia, Pa, American Society for Testing and Materials.
17.
W. Moller: in ‘Deposition and corrosion in gas turbines’, (ed. A. B. Hart and A. J. B. Cutler), 1–16; 1973, New York, John Wiley and Sons.
18.
J. F. G. condé and B. A. Wareham: in Ref. 8, 73–92.
19.
A. F. Taylor, B. A. Wareham, G. C. Booth, and J. F. G. Condé: in Ref. 9, Session III, Paper 3.
20.
P. Carter: in Ref. 10, 1–9.
21.
G. B. Katz and B. J. Rogus: in Ref. 10, 12–18.
22.
D. J. Wortman, R. E. Fryxell, and I. I. Bessen: in Ref. 9, Session V, Paper 11.
23.
R. E. Fryxell: ‘Effects of surface chemistry on hot corrosion life’, First Annual Report NASA CR-174683, NASA, Washington DC, 1984.
24.
P. R. Belcher, R. J. Bird, and R. W. Wilson: in Ref. 16, p. 123.
25.
I. I. Bessen and R. E. Fryxell: in Ref. 7, 73–84.
26.
C. G. McCreath: in Ref. 9, Session V, Paper 2.
27.
M. A. DeCrescente and N. S. Bornstein: Corrosion , 1968, 24 , 127.
28.
S. G. Morgan, A. W. Lamport, and A. J. R. Smith: Paper presented at meeting on ‘Gas turbines’, New York, American Society of Mechanical Engineers, 1970, 70–GT–10.
29.
J. G. Tschinkel: Corrosion , 1972, 28 , 161.
30.
E. L. Simons, G. V. Browning, and H. A. Liebhafsky: Corrosion , 1955, 11 , 505t.
31.
R. S. Hollingshead: ‘Effect of zinc on the sulfidation reaction in marine gas turbines’, Report 80/2, Defense Research Establishment Atlantic, Dartmouth, NS, 1980.
32.
J. G. Foggo, III, D. B. Nordman, and R. L. Jones: ‘Inhibition of low temperature hot corrosion by Zn, Na mixed sulfates’, Report 5068, Naval Research Laboratory, Washington, DC, 1983.
33.
H. C. Gear and R. A. Collins: in Ref. 9, Session I, Paper 1.
34.
J. Stringer: Ann. Rev. Mater. Sci. , 1977, 7 , 477–509.
35.
A. V. Dean: ‘Investigation into the resistance of various nickel and cobalt base alloys to sea salt corrosion at elevated temperatures’, NGTE Report, National Gas Turbine Establishment, Pyestock, Hants, 1964.
36.
M. N. Richards and J. Stringer: Br. Corros. J. , 1973, 8 , 167–172.
37.
N. Swindells, K. Raper, and M. Stuart: High Temp. Technol. , 1983, 1 , 139–145.
38.
R. W. Hardt, J. R. Gambino, and P. A. Bergman: in Ref. 16, p. 64.
39.
J. A. Goebel and F. S. Pettit: Metall. Trans. , 1970, 1 , 1943 and 3421.
40.
N. S. Bornstein, M. A. DeCrescente, and H. A. Roth: in Ref. 7, 3–15.
41.
K. R. Peters: Ph.D. thesis, University of Liverpool, 1977.
42.
K. R. Peters, D. P. Whittle, and J. stringer: Corros. Sci. , 1976, 16 , 791–804.
43.
H. Morrow, D. L. Sponseller, and E. Kalns: Metall. Trans. , 1974, 5 , 673.
44.
N. S. Bornstein, M. A. DeCrescente, and H. A. Roth: Report M910983-5, US Department of the Navy, Washington D.C., 1973.
45.
D. M. Johnson, D. P. Whittle, and J. Stringer: Corros. Sci. , 1975, 15 , 649–661.
46.
M. H. Davis, H. C. Graham, and G. F. Uhlig: Metall. Trans. , 1972, 3 , 3247.
47.
V. Nagarajan, J. Stringer, and D. P. Whittle: Corros. Sci. , 1982, 22 , 407–427.
48.
V. Nagarajan, J. Stringer, and D. P. Whittle: Corros. Sci. , 1982, 22 , 429–439.
49.
V. Nagarajan, J. Stringer, and D. P. Whittle: Corros. Sci. , 1982, 22 , 441–453.
50.
C. Spengler and R. Viswanathan: Metall. Trans. , 1972, 3 , 161.
51.
M. E. El Dahshan, D. P. Whittle, and J. Stringer: Oxid. Met. , 1974, 8 , 179.
52.
M. E. El Dahshan, J. Stringer, and D. P. Whittle: Oxid. Met. , 1974, 8 , 211.
53.
J. Stringer and M. E. El Dahshan: in Ref. 8, 161.
54.
W. T. Reid: ‘External corrosion and deposits: boilers and gas turbines’; 1971, New York, Elsevier.
55.
L. F. Aprigliano: ‘Burner rig simulation of low-temperature hot corrosion’, Report MCIC-79-40, Metals and Ceramics Information Centre, Columbus, Ohio, 1979.
56.
D. J. Wortman, R. E. Fryxell, K. L. Luthra, and P. A. Bergman: in Ref. 10, 317–331.
57.
L. F. Aprigliano: in Ref. 10, 151–188.
58.
F. S. Kemp (principal investigator) et al. : ‘Protective coatings for utility gas turbines’, Final Report No. AP-2929, Project RP1344-1, United Technologies Corporation, Power Services Division, Electric Power Research Institute, Palo Alto, Cal., 1983.
59.
J. J. Grisik, R. G. Miner, and D. J. Wortman: Thin Solid Films , 1980, 73 , 397–406.
60.
G. Baudo: Coatings Corrosion , 1977, 1 , 11–41.
61.
A. Rahmel: Werkst. Korros. , 1968, 19 , 750.
62.
E. Tatar-Moisescu and A. Rahmel: Electrochim. Acta , 1975, 20 , 479.
63.
A. Rahmel: Electrochim. Acta , 1976, 21 , 853.
64.
A. J. B. Cutler and C. J. Grant: ‘Deposition and corrosion in gas turbines’, (ed. A. B. Hart and A. J. B. Cutler), 178–196; 1973, New York, Halsted Press.
65.
V. Vasantasree, M. G. Hocking, and B. A. Nagaraj: in Ref. 9, Session V, Paper 4a.
66.
V. Vasantasree and M. G. Hocking: in Ref. 9, Session V, Paper 4b.
67.
E. Erdos, H. Altorfer, and E. Denzler: Werkst. Korros. , 1986, 33 , 373–385.
68.
W. T. Wu, A. Rahmel, and M. Schorr: Oxid. Met. , 1983, 19 , 201–229.
69.
J. F. G. Condé, E. Erdos, and A. Rahmel: in ‘High temperature alloys for gas turbines 1982’, (ed. R. Brunetaud et al. ), 99–148; 1982, Dordrecht, Holland, D. Reidel Publishing Co.
70.
W. P. Stroud and R. A. Rapp: ‘High temperature metal halide chemistry’, (ed. D. L. Hildenbrand and D. D. Cubicciotti), 547; 1978, Princeton, N.J., Electrochemical Society.
71.
D. K. Gupta and R. A. Rapp: J. Electrochem. Soc. , 1980, 127 , 2194.
72.
R. A. Rapp and K. S. Goto: ‘Corrosion in fused salts’, (ed. J. Braunstein and J. R. Selman), 159; 1981, Princeton, N.J., The Electrochemical Society.
73.
Y. S. Zhang and R. A. Rapp: J. Electrochem. Soc. , 1985, 132 , 734 and 2498.
74.
Y. S. Zhang: J. Electrochem. Soc. , 1986, 133 , 655.
75.
C. S. Giggins and F. S. Pettit: ‘A unified theory of hot corrosion’, Final Report No. FR-11545, US Air Force Office of Scientific Research, 1979.
76.
R. A. Rapp (ed.): ‘High temperature corrosion’, NACE-6; 1983, Houston, Tex., National Association of Corrosion Engineers.
77.
P. Hancock: in Ref. 8, 225–236.
78.
D. W. McKee and G. Romeo: in Ref. 8, 183–194.
79.
J. C. Galsworthy, J. E. Restall, and G. C. Booth: ‘High temperature alloys for gas turbines’, (ed. R. Brunetaud et al. ), 207–235; 1982, Dordrecht, Holland, D. Reidel Publishing Co.
80.
R. H. Barkalow, J. A. Goebel, and F. S. Pettit: ‘Materials problems in fluidized-bed combustion systems: high-temperature erosion corrosion by high-velocity (> 200 m/s) particles’, Final Report No. CS-1448, Project RP979-4, Electric Power Research Institute, Palo Alto, Cal., 1980.
81.
R. H. Barkalow: ‘Erosion-corrosion by high-velocity particles in fluidized bed combustion systems’, Final Report No. CS-3396, Project RP979-4, Electric Power Research Institute, Palo Alto, Cal., 1984.
82.
J. Stringer, D. P. Whittle, and R. K. Hughes: Corros. Sci. , 1977, 17 , 187–192.
83.
R. C. Hurst, J. B. Johnson, M. Davies, and P. Hancock: ‘Deposition and corrosion in gas turbines’, (ed. A. B. Hart and A. J. B. Cutler), 143–157; 1973, New York, Halsted Press.
84.
P. Hancock and J. R. Nicholls: Ref. 10, 403–422.
85.
S.-H. Choi and J. Stringer: paper presented to Annual Meeting of Electrochemical Society, Las Vegas, Nev., July 1985.
86.
S.-H. Choi: PhD thesis, Lawrence Berkeley Laboratory, University of California, 1985.
87.
N. S. Bornstein and M. A. DeCrescente: Trans. AIME , 1969, 245 , 1947.
88.
J. A. Goebel, F. S. Pettit, and G. W. Goward: Metall Trans. , 1975, 4 , 261.
89.
H. H. Krause, A. Levy, and W. T. Reid: Trans. ASME, J. Eng. Power, Ser. A , 1968, 90 , 38–44.
90.
D. A. Shores: in Ref. 76, pp. 493–506.
91.
K. L. Luthra: in Ref. 76, pp. 507–518.
92.
K. L. Luthra and D. A. Shores: J. Electrochem. Soc. , 1980, 127 , 2202.
93.
A. K. Misra, D. P. Whittle, and W. L. Worrell: J. Electrochem. Soc. , 1982, 129 , 1840–1845.
94.
R. C. Corey, B. J. Cross, and W. T. Reid: Trans. ASME , 1945, 67 , 279.
95.
C. Cain, Jr and W. Nelson: Trans. ASME, J. Eng. Power, Ser. A , 1961, 83 , 468.
96.
I. M. Rehn: ‘Corrosion problems in coal-fired boiler superheater and reheater tubes – fireside corrosion’, Final Report No. CS-1653, Project RP644-1, Electric Power Research Institute, Palo Alto, Cal., 1982.