Hot Corrosion Behaviour of Yttria-Stabilised Zirconia as Plasma Sprayed Coated Boiler Steel in Air and Salt at 900°C under Cyclic Condition

Dinesh Gond, D. Puri, S. Prakash

HEEP, Bharat Heavy Electricals Ltd. (Government of India Undertaking) Haridwar, India..
Metallurgical & Materials Engineering Department, Indian Institute of Technology Roorkee,India.

DOI: 10.4236/jmmce.2011.105035                

Abstract

Yttria-Stabilised Zirconia (YSZ) coatings were deposited on a T-22 boiler steel. NiCrAlY was used as bond coat and YSZ as top coat. Hot corrosion studies were conducted on uncoated as well as plasma spray coated specimens in air as well as salt (75 wt.% Na₂SO₄ + 25 wt.% NaCl) at 900°C under cyclic conditions. The thermogravimetric technique was used to establish kinetics of corrosion. X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive x-ray analysis (SEM/EDAX) techniques were used to analyse the corrosion products. This YSZ overlay coatings enhance resistance to corrosion significantly which can be attributed to formation of zirconium oxides (ZrO₂) and yttrium oxide (Y₂O₃). This coating was more effective in salt environment and there is an extra phase of ZrS.

Keywords

Hot corrosion; T-22; Plasma spray coating.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Lai G Y, Pub. ASM International (1990) Chapter 3, 15.
[2]	Harpreet Singh, D. Puri, S. Prakash, Surf. Coat. Technol. 192 (2004) 27– 38.
[3]	K.G. Bundinski, Surface Engineering for Wear Resistance, Prentice-Hall, New Jersey, 1988.
[4]	M.K. Hobbs, H. Reiter, Residual stresses in ZrO2–8%Y2O3 plasma sprayed thermal barrier coatings, in: D.L. Houck (Ed.), Thermal Spray: Advances in Coatings Technology, ASM International (1989) 285–290.
[5]	H. Herman, C.C. Berndt, H. Wang, Plasma sprayed ceramic coatings, in: J.B. Wachtman, R.A. Haber (Eds.), Ceramic Films and Coatings, Noyes Publications, New Jersey, (1993).
[6]	L. Pawlowski, The Science and Engineering of Thermal Spray Coatings, Wiley, New York, (1995).
[7]	A.G. Evans, D.R. Mumm, J.W. Hutchinson, G.H. Meier, F.S. Pettit, Prog. Mater. Sci. 46 (2001) 505.
[8]	J.R. Brandon, R. Taylor, Surf. Coat. Techol. 69 (10) (1992) 75.
[9]	I. Gurrappa, J. Mater. Sci. Lett. 17 (1998) 1267.
[10]	R.L. Jones, J. Therm. Spray Technol. 6 (1) (1997) 77.
[11]	B.A. Nagaraj, D.J. Wortman, Trans. ASME 112 (1990) 536.
[12]	R. Srinivasan, J.M. Merrilea, Surf. Coat. Technol. 160 (2002) 187.
[13]	R.L. Jones, J. Am. Ceram. Soc. 75 (7) (1992) 1818.
[14]	P. Niranatlumpong, C.B. Ponton, H.E. Evans, Oxid. Met. 53 (3–4) (2000) 241.
[15]	Buta Singh Sidhu, S. Prakash, Surf. Coat. Technol. 201 (2006) 1643–1654.
[16]	R.A. Rapp, J.H. Devan, D.L. Douglass, P.C. Nordine, F.S. Pettit, D.P.Whittle, Mater. Sci.Eng.50 (1981) 1.
[17]	P.S. Liu, K.M. Liang, H.Y. Zhou, S.R. Gu, X.F. Sun, H.R. Guan, T. Jin, K.N. Yang, Surf. Coat. Technol. 145 (2001) 75.
[18]	Kimura K, Kushima H, Abe F, Yagi K, Irie H. In: Strang A, Banks WM, Conroy RD, Goulette MJ, “Advances in turbine materials, design and manufacturing”. London: The Institute of Materials, (1997) 257–69.
[19]	J.C. Van Wortel, C.F. Etienne, F. Arav, “Application of modified 9chromium steels in power generation components, in: VDEh ECSC Information Day, The Manufacture and Properties of Steel 91 for the Power Plant and Process Industries”, Dusseldorf, (1992) 4.2.
[20]	J. Orr, A. Di Gianfrancesco, “The effect of compositional variations on the properties of steel 91, in: VDEh ECSC Information Day, The Manufacture and Properties of Steel 91 for the Power Plant and Process Industries”, Dusseldorf, (1992) 2.4.
[21]	N.S. Bornstein, M.A. Decrescente, H.A. Roth, MMIC-75-27, Columbus, Ohio, USA, (1975) 115.
[22]	C. Batista, A. Portinha, R.M. Ribeiro, V. Teixeira, C.R. Oliveira, Surf. Coat. Technol. 200 (2006) 6783–6791.
[23]	R.A.Miller, R.G. Garlick, J.L. Smialek, Ceram. Bull. 62 (12) (1983) 1355.
[24]	A.N. Khan, J. Lu, H. Liao, Mater. Sci. Eng., A Struct. Mater.: Prop.Microstruct. Process. 359 (2003) 129.
[25]	S.Y. Park, J.H. Kim, M.C. Kim, H.S. Song, C.G. Park, Surf. Coat. Technol.190 (2005) 357-365.