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

Sadeghimeresht, Esmaeil; Reddy, Liam; Hussain, Tanvir; Markocsan, Nicolaie; Joshi, Shrikant

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.

Citation

Sadeghimeresht, E., Reddy, L., Hussain, T., Markocsan, N., & Joshi, S. (2018). Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings. Corrosion Science, 132, https://doi.org/10.1016/j.corsci.2017.12.033

• Journal Article Type: Article
• Acceptance Date: Dec 26, 2017
• Online Publication Date: Dec 28, 2017
• Publication Date: Mar 31, 2018
• Deposit Date: Feb 9, 2018
• Publicly Available Date: Dec 29, 2018
• Journal: Corrosion Science
• Print ISSN: 0010-938X
• Electronic ISSN: 1879-0496
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 132
• DOI: https://doi.org/10.1016/j.corsci.2017.12.033
• Keywords: Thermal spray coating; NiCr; NiAl; High-velocity air fuel (HVAF); Biomass-/waste-fired boiler; Fireside corrosion
• Public URL: https://nottingham-repository.worktribe.com/output/923161
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0010938X1731096X?via%3Dihub
• Contract Date: Feb 9, 2018