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Microstructures, thermophysical properties and thermal cycling behavior of LaZnAl11O19 thermal barrier coatings deposited by atmospheric plasma spraying

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Abstract

Magnetoplumbite-type LaMgAl11O19 with high thermal stability and excellent sintering resistance has been proposed as a promising thermal barrier coating (TBC) material for next generation gas turbines. However, LaMgAl11O19 shows poor stability at 1500 °C in humid environments caused by H+/Mg2+ ionic exchange. In this work, a LaZnAl11O19 coating which is supposed to possess enhanced anti-deliquescent property was produced by plasma spraying and its properties as a potential TBC were comprehensively investigated. The results show that the thermal conductivity of the as-sprayed LaZnAl11O19 coating ranges from 1.24 W m−1 K−1 to 1.46 W m−1 K−1 and the average thermal expansion coefficient is less than 6.0 × 10−6 K−1 due to the presence of an amorphous phase in the as-sprayed coating. During exposure to 1300 °C, a total porosity of ∼10.5% can be maintained even after 1000 h aging, indicating a high sintering resistance. Besides, nano-sized grains recrystallized from the molten lamellae give the LaZnAl11O19 coating enhanced mechanical properties. In 1100 °C furnace cyclic testing, the LaZnAl11O19/YSZ double-ceramic-layer TBC exhibits a thermal cycling lifetime of ∼669 cycles, which is about 1.7 and 1.16 times as long as the conventional YSZ coating and the LaMgAl11O19/YSZ TBC, respectively. The results indicate that LaZnAl11O19 might be a promising candidate for advanced TBC applications.

Graphical abstract: Microstructures, thermophysical properties and thermal cycling behavior of LaZnAl11O19 thermal barrier coatings deposited by atmospheric plasma spraying

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Publication details

The article was received on 28 Aug 2019, accepted on 26 Sep 2019 and first published on 27 Sep 2019


Article type: Research Article
DOI: 10.1039/C9QI01104H
Inorg. Chem. Front., 2019, Advance Article

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    Microstructures, thermophysical properties and thermal cycling behavior of LaZnAl11O19 thermal barrier coatings deposited by atmospheric plasma spraying

    F. Liu, W. Song, X. Zhou, P. Huo, J. Yuan, J. Jiang, L. Deng, S. Dong and X. Cao, Inorg. Chem. Front., 2019, Advance Article , DOI: 10.1039/C9QI01104H

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