Development and Understanding of CMAS Coating on YSZ Using APS Technique

The ingestion of siliceous particulate debris into the gas turbine engines during operation caused the deposition of so-called CMAS (calcium-magnesium-alumino-silicate) on the hotter thermal barrier coating (TBC) surfaces. The penetration of these particles into the TBC at temperatures above 1200°C caused the loss of strain tolerance and premature failure of the TBCs. To mimic real-world conditions, a commercially available CMAS precursor dust powder was sprayed onto 8YSZ coatings using an atmospheric plasma spraying process. The substrate temperature was maintained at an average of 1100°C and 525°C during spraying. The effect of the spraying parameters on the deposition, microstructure, and composition of the CMAS coatings was investigated. In addition, to understand the CMAS build-up on the high-temperature surfaces, the CMAS splat formation behavior was also analyzed on the polished samples at temperatures ~1100°C. SEM/EDS analyzes were performed to identify and quantify the elements of the CMAS deposits. It was found that the surface temperature, deposition time, and different nozzles could play a significant role in having different phases of CMAS deposits.

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Key words: atmospheric plasma spraying, calcium-magnesium-alumino-silica coatings, chemical composition, microstructure, thermal barrier coatings, yttria-stabilized zirconia

Originally published at ITSC2024 Proceedings online paper (Paper No: itsc2024p0176, pp. 176-184; 9 pages)
By Amit Roy, Fadhel Ben Ettouil, Rogerio S. Lima, Christian Moreau