Enhancement of Corrosion Resistance of Al2O3 + Sm2SrAl2O7 Composite Thermal Barrier Coatings by Laser Treatment
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Date
2024
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Springer
Abstract
The rare earth aluminate Sm<inf>2</inf>SrAl<inf>2</inf>O<inf>7</inf> was synthesized in the laboratory through a molten salt synthesis technique at 1100 °C. A composite thermal barrier coating system on Inconel 718 substrate was developed with Al<inf>2</inf>O<inf>3</inf>–Sm<inf>2</inf>SrAl<inf>2</inf>O<inf>7</inf> composite as the top coat and NiCrAlY as the bond coat using atmospheric plasma spraying. The surface of the plasma-sprayed coatings was treated using an Nd: YAG fiber laser to seal off the open porosities and reduce surface roughness. Hot corrosion tests on the laser-modified samples were performed at 700 °C and 900 °C, in aviation and marine corrosive conditions using 50 wt.% Na<inf>2</inf>SO<inf>4</inf> + 50 wt.% V<inf>2</inf>O<inf>5</inf> and 90 wt.% Na<inf>2</inf>SO<inf>4</inf> + 5 wt.% V<inf>2</inf>O<inf>5</inf> + 5 wt.% NaCl, respectively. The laser-treated samples showed higher resistance to failure than the as-coated samples under similar conditions. The corrosion products are identified, and the mechanisms involved are discussed in detail. The effect of surface modifications on the hot corrosion resistance of the coatings is investigated. © The Indian Institute of Metals - IIM 2023.
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Keywords
Alumina, Aluminum oxide, Composite coatings, Corrosion resistant coatings, Corrosive effects, Fiber lasers, Magnesium compounds, Neodymium compounds, Neodymium lasers, Plasma jets, Plasma spraying, Rare earths, Samarium compounds, Seawater corrosion, Sodium Aluminate, Sodium chloride, Sodium sulfate, Sprayed coatings, Strontium compounds, Surface roughness, Thermal barrier coatings, Vanadium pentoxide, Yttrium aluminum garnet, Hot corrosion, Inconel-718, Laser treatment, Molten salts synthesis, Rare earth aluminate, Samarium strontium aluminate, Surface-modification, Synthesis techniques, Synthesised, Thermal barrier coating systems, Corrosion resistance
Citation
Transactions of the Indian Institute of Metals, 2024, 77, 5, pp. 1381-1391