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- Title
Cyclic Oxidation and Hot-Corrosion Behavior of HVOF-Sprayed NiCrAl Coating on Industrial Boiler Tube Steels.
- Authors
Ramesh, M. R.; Medabalimi, Subbarao; Kumar, R. Suresh; Prasad, C. Durga; Sollapur, Shrishail B.
- Abstract
At high temperatures, coatings provide a protective scale development on surfaces to maintain long-term stability. In the current study, ASTM-SA210-Grade A1 (GrA1) and ASTM-SA213-T-11 (T11) boiler tube steels were coated with NiCrAl alloy with high-velocity oxy-fuel (HVOF) to prevent oxidation and hot corrosion. For hot corrosion and oxidation, 50 cycles at 900°C were taken into account. Additionally, tests of hot-corrosion behavior were conducted in an atmosphere containing molten salt (Na2SO4-60%V2O5), while tests of oxidation behavior were conducted in static air. The kinetics of oxidation were calculated using the thermogravimetric method. Using XRD, EPMA, and SEM/EDAX methods, the produced oxide scales were characterized. The oxidation rate of NiCrAl-coated steels was found to be lower than that of uncoated steels. The coated steels subjected to oxidation in air exhibit slow scale growth kinetics and oxides of α-Al2O3 and Cr2O3 on the outermost surface, while accelerated oxidation caused by the molten salt exhibits metastable Al2O3. Along the nickel-rich splat boundary, Cr and Al were formed a preferential oxidation, which prevents other oxygen from entering the coating via pores and voids, resulting in steady-state oxidation.
- Subjects
STEEL tubes; PROTECTIVE coatings; BOILERS; OXIDATION kinetics; SURFACE coatings; STEEL; OXIDATION
- Publication
JOM: The Journal of The Minerals, Metals & Materials Society (TMS), 2024, Vol 76, Issue 6, p3172
- ISSN
1047-4838
- Publication type
Article
- DOI
10.1007/s11837-024-06526-1