Isothermal oxidation characteristics of laser‐treated Al2O3 + Sm2SrAl2O7 composite thermal barrier coatings

A thermal barrier coating system with Al2O3 + Sm2SrAl2O7 composite top coat was developed on an Inconel 718 superalloy substrate by using an atmospheric plasma spray technique, and the coated samples are treated with an Nd:YAG fiber laser to improve the surface properties. The as‐coated and laser‐tr...

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Bibliographic Details
Published in:Materials and corrosion 2023-08, Vol.74 (8), p.1169-1182
Main Authors: James Joseph, Fredy, Arya, Shashi Bhushan, D, Satish Kumar
Format: Article
Language:English
Subjects:
Aluminum oxide
Coatings
electrochemical impedance
Fiber lasers
High temperature
isothermal oxidation
Neodymium lasers
Nickel base alloys
Oxidation tests
Reaction kinetics
samarium strontium aluminate
Substrates
Superalloys
Surface properties
Thermal barrier coatings
thermally grown oxide
YAG lasers
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Summary:A thermal barrier coating system with Al2O3 + Sm2SrAl2O7 composite top coat was developed on an Inconel 718 superalloy substrate by using an atmospheric plasma spray technique, and the coated samples are treated with an Nd:YAG fiber laser to improve the surface properties. The as‐coated and laser‐treated samples were subjected to high temperature isothermal oxidation test at 1100°C for 150 h duration. The surface of the oxidized samples showed the presence of dissociated SmAlO3, SrAl2O4, and Sm2O3. Thermally grown oxides (TGO) are found at the bond coat top coat interface of the samples. The oxidation kinetics is examined by monitoring weight gain at regular intervals. The electrochemical impedance behavior, oxidation mechanism, and TGO formation in the developed composite coatings are discussed in detail. The developed Al2O3 + Sm2SrAl2O7 composite thermal barrier coatings showed a high resistance against isothermal oxidation at 1100°C. A laser treatment on the coated surface further enhanced the oxidation resistance by sealing off the open porosities on the surface. The oxidation kinetics observed are discussed in detail.
ISSN:0947-5117
1521-4176
DOI:10.1002/maco.202313813