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Influence of powder particle size on the microstructure and thermal shock resistance of plasma-sprayed yttria-stabilized zirconia coatings.

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Title: Influence of powder particle size on the microstructure and thermal shock resistance of plasma-sprayed yttria-stabilized zirconia coatings.
Authors: Che, Yanhao1,2 (AUTHOR), Li, Ning1,2 (AUTHOR), Bao, Zebin1,2 (AUTHOR) xycui@imr.ac.cn, Cui, Xinyu1,2 (AUTHOR) zbbao@imr.ac.cn
Source: Ceramics International. Apr2026:Part A, Vol. 52 Issue 9, p11653-11665. 13p.
Subjects: Microstructure, Thermal shock, Gas turbines, Plasma spraying, Thermocycling, Thermal barrier coatings, Yttria stabilized zirconium oxide
Abstract: Thermal barrier coatings (TBCs) are essential for protecting hot-section components in gas turbines, yet their spallation under thermal cycling remains a key challenge, largely governed by their microstructural characteristics. The effect of powder particle size on the microstructure and thermal shock resistance of atmospheric plasma-sprayed yttria-stabilized zirconia (YSZ) coatings was systematically investigated in this study. Three YSZ powders with distinct size distributions were deposited onto CoNiCrAlY-bonded substrates, and the resulting coatings were subjected to cyclic thermal shock tests from 1000 °C to ambient temperature. Results show that finer powders promote more complete melting and improved thermal homogeneity, leading to denser coatings with flattened lamellar structures, reduced porosity, lower surface roughness, and stronger interlamellar bonding. Thermal shock failure initiates at intrinsic defects such as pores and unmelted particles, where cracks nucleate and propagate both laterally and vertically, eventually interconnecting and causing spallation—most notably in the central region where the maximum strain is concentrated. The refined microstructure from fine powders effectively suppresses crack initiation and propagation, while a network of microcracks helps dissipate thermal stress without developing into destructive cracks. Furthermore, thermal cycling induced microstructural evolution involving recovery and recrystallization, the degree of which is influenced by the initial coating microstructure dictated by powder size. This work establishes a critical correlation between powder particle size, microstructure, and thermal shock performance, providing valuable guidance for designing high-durability TBCs by powder feedstock optimization. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Thermal barrier coatings (TBCs) are essential for protecting hot-section components in gas turbines, yet their spallation under thermal cycling remains a key challenge, largely governed by their microstructural characteristics. The effect of powder particle size on the microstructure and thermal shock resistance of atmospheric plasma-sprayed yttria-stabilized zirconia (YSZ) coatings was systematically investigated in this study. Three YSZ powders with distinct size distributions were deposited onto CoNiCrAlY-bonded substrates, and the resulting coatings were subjected to cyclic thermal shock tests from 1000 °C to ambient temperature. Results show that finer powders promote more complete melting and improved thermal homogeneity, leading to denser coatings with flattened lamellar structures, reduced porosity, lower surface roughness, and stronger interlamellar bonding. Thermal shock failure initiates at intrinsic defects such as pores and unmelted particles, where cracks nucleate and propagate both laterally and vertically, eventually interconnecting and causing spallation—most notably in the central region where the maximum strain is concentrated. The refined microstructure from fine powders effectively suppresses crack initiation and propagation, while a network of microcracks helps dissipate thermal stress without developing into destructive cracks. Furthermore, thermal cycling induced microstructural evolution involving recovery and recrystallization, the degree of which is influenced by the initial coating microstructure dictated by powder size. This work establishes a critical correlation between powder particle size, microstructure, and thermal shock performance, providing valuable guidance for designing high-durability TBCs by powder feedstock optimization. [ABSTRACT FROM AUTHOR]
ISSN:02728842
DOI:10.1016/j.ceramint.2026.01.324