Microstructural Features and Oxidation Behaviour of NiCrAlY Coatings Obtained by HVOF Process


Article Preview

NiCrAlY coating system has been widely used for the advanced gas turbines to provide protection against high temperature oxidation and corrosion. Various methods have been used to develop these superalloy coatings. In present investigation, NiCrAlY superalloy coatings have been deposited on the superalloy substrate (Superni76) using commercially available NiCrAlY powder and High Velocity Oxide Fuel (HVOF) process. These coatings have been characterised in terms of their microhardness, porosity, microstructure features and surface roughness. The coatings have been oxidized cyclically (1hour heating and 20minutes cooling) in air at 900οC. The weight change curves have been plotted and the parabolic rate constant has been evaluated. The oxides formed after oxidation has been studied by using various techniques like optical microscopy, FESEM/EDAX and XRD. It has been observed Al¬2O3, NiCr2O4 and Cr2O3 formed upon oxidation of the coatings provide protection to the substrate alloy.



Edited by:

B.S.S. Daniel and G.P. Chaudhari




N. Rana et al., "Microstructural Features and Oxidation Behaviour of NiCrAlY Coatings Obtained by HVOF Process", Advanced Materials Research, Vol. 585, pp. 507-511, 2012

Online since:

November 2012





[1] M.H. Li et al, Oxidation behaviour of sputter-deposited NiCrAlY coating, Surf. Coat. Technol. 165 (2003) 241–247.

[2] S. Kamal, R. Jayaganthan and S. Prakash, Hot Corrosion Studies of Detonation-Gun-Sprayed NiCrAlY + 0. 4 wt. % CeO2 Coated Superalloys in Molten Salt Environment, JMEPEG 20 (2011) 1068-1077.

DOI: https://doi.org/10.1007/s11665-010-9728-8

[3] Q. Zhang et al., Effect of powder structure on microstructure of the oxide scales formed on cold sprayed NiCrAlY coatings, IJMPB 24 (2010) 3041-3046.

[4] D. Seo et al., High-temperature Oxidation Behavior and Surface Roughness Evolution of VPS NiCrAlY Coating, J. Therm. Spray Technol. 17 (2008) 136-143.

DOI: https://doi.org/10.1007/s11666-007-9150-4

[5] M. Oksa et al, Optimization and Characterization of High Velocity Oxy-fuel Sprayed Coatings: Techniques, Materials, and Applications, Coatings 1 (2011) 17-52.

DOI: https://doi.org/10.3390/coatings1010017

[6] M. Taheri, Z. Valefi and K. Zangeneh-Madar, Influence of HVOF process parameters on microstructure and bond strength of NiCrAlY coatings, Surf. Eng. 28 (2012) 266-272.

DOI: https://doi.org/10.1179/1743294411y.0000000024

[7] M. Di Ferdinando et al, Isothermal oxidation resistance comparison between air plasma sprayed, vacuum plasma sprayed and high velocity oxygen fuel sprayed CoNiCrAlY bond coats, Surf. Coat. Technol. 204 (2010) 2499–2503.

DOI: https://doi.org/10.1016/j.surfcoat.2010.01.031

[8] D. Toma, Waltraut Brandl , Uwe Ko¨ ster, Studies on the transient stage of oxidation of VPS and HVOF sprayed MCrAlY coatings, Surf. Coat. Technol. 120–121 (1999) 8–15.

DOI: https://doi.org/10.1016/s0257-8972(99)00332-1

[9] M.C. Mayoral et al, Aluminium depletion in NiCrAlY bond coatings by hot corrosion as a function of projection system, Surf. Coat. Technol. 202 (2008) 1816–1824.

DOI: https://doi.org/10.1016/j.surfcoat.2007.07.068

[10] R.A. Mahesh, R. Jayaganthan, S. Prakash, Microstructural characteristics and mechanical properties of HVOF sprayed NiCrAl coating on superalloys, J. Alloys Compd. 468 (2009) 392–405.

DOI: https://doi.org/10.1016/j.jallcom.2008.01.025

[11] Y.N. Wua et al., Improved oxidation resistance of NiCrAlY coatings, Mater. Lett. 57 (2003) 2404–2408.

[12] V. H. Hidalgo, F.J. Belzunce Varela and E. F. Rico, Erosion wear and mechanical properties of plasma-sprayed nickel- and iron-based coatings subjected to service conditions in boilers, Tribol. Int. 30 (1997) 641–649.

DOI: https://doi.org/10.1016/s0301-679x(97)00029-7

[13] D. Delaunay, A.M. Huntz and P. Lacombe, Mechanical stresses developed in high temperature resistant alloys during isothermal and cyclic oxidation treatments: The influence of yttrium additions on oxide scale adherence, Corrosion Science 20 (1980).

DOI: https://doi.org/10.1016/0010-938x(80)90141-9

[14] F. Tang, L. Ajdelsztajn, and J. M. Schoenung, Influence of Cryomilling on the Morphology and Composition of the Oxide Scales Formed on HVOF CoNiCrAlY Coatings, Oxid. Met. 61 3/4 (2004) 219-238.

DOI: https://doi.org/10.1023/b:oxid.0000025332.26757.41