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High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications

Authors
  • Eklund, J.1
  • Phother, J.1
  • Sadeghi, E.2
  • Joshi, S.2
  • Liske, J.1
  • 1 Chalmers University of Technology, Energy and Materials, Department of Chemistry and Chemical Engineering, Göteborg, 412 96, Sweden , Göteborg (Sweden)
  • 2 University West, Department of Engineering Science, Trollhättan, 46153, Sweden , Trollhättan (Sweden)
Type
Published Article
Journal
Oxidation of Metals
Publisher
Springer US
Publication Date
Mar 14, 2019
Volume
91
Issue
5-6
Pages
729–747
Identifiers
DOI: 10.1007/s11085-019-09906-0
Source
Springer Nature
Keywords
License
Green

Abstract

The present study investigates the initial corrosion behaviour of HVAF-sprayed NiCr, NiAl and NiCrAlY coatings in two different environments, O2 + H2O and O2 + H2O + KCl at 600 °C for up to 168 h in order to evaluate the possibility of utilizing such coatings in biomass- and waste-fired boilers. SEM/EDX analysis showed that all coatings displayed a protective behaviour in O2 + H2O. Upon addition of KCl (O2 + H2O + KCl), the corrosion behaviour of the NiCr coating drastically changed as it formed a thick oxide layer and displayed major chlorine diffusion down to the substrate. The NiCrAlY coating displayed a significantly better corrosion resistance with only minor oxide formation. The NiAl coating exhibited a protective behaviour similar to when exposed in the absence of KCl indicating that a thin protective oxide has formed on the coating surface. The performance of the NiAl and NiCrAlY coatings is promising for future studies with long-term exposures in more corrosive environments such as in a biomass- and waste-fired boiler.

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