Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

Sadeghimeresht, Esmaeil and Reddy, Liam and Hussain, Tanvir and Markocsan, Nicolaie and Joshi, Shrikant (2018) Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings. Corrosion Science, 132 . pp. 170-184. ISSN 1879-0496

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Abstract

Chlorine-induced corrosion of HVAF-sprayed Ni21Cr and Ni5Al coatings was investigated in 5 vol.% O2 + 500vppm HCl + N2 with and without KCl at 600 °C up to 168 h. Both coatings were protective in the absence of KCl. With KCl, Ni21Cr degraded through a two-stage mechanism: 1) formation of K2CrO4 followed by diffusion of Cl− through the oxide grain boundaries to yield chlorine and a non-protective oxide, and 2) inward diffusion of chlorine though defects in the non-protective oxide, leading to breakaway oxidation. Cl−/Cl2 could not diffuse through the protective alumina scale formed on Ni5Al, hence the corrosion resistance increased.

Item Type: Article
Keywords: Thermal spray coating; NiCr; NiAl; High-velocity air fuel (HVAF); Biomass-/waste-fired boiler; Fireside corrosion
Schools/Departments: University of Nottingham, UK > Faculty of Engineering > Department of Mechanical, Materials and Manufacturing Engineering
Identification Number: 10.1016/j.corsci.2017.12.033
Depositing User: Eprints, Support
Date Deposited: 09 Feb 2018 10:53
Last Modified: 22 Feb 2018 07:40
URI: http://eprints.nottingham.ac.uk/id/eprint/49692

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