Microstructures and Properties of Sm2(Zr0.7Ce0.3)2O7/8YSZ Double-Ceramic-Layer Thermal Barrier Coatings Deposited by Atmospheric Plasma Spraying
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The properties of Sm2(Zr0.7Ce0.3)2O7 (SZ7C3) as a novel thermal barrier coating (TBC) candidate have been evaluated. There is no evidence for a phase transformation for SZ7C3 from room temperature to 1600 °C. SZ7C3 exhibits a higher sintering resistance than the conventional yttria-stabilized zirconia (YSZ). The Vickers hardness for the SZ7C3 bulk is ca. 9.6 GPa, and the fracture toughness lies in a range of 1.5-2.5 MPa m1/2. Single SZ7C3 coatings and SZ7C3/8YSZ double-ceramic-layer (DCL) coatings were prepared by plasma spraying. The thermal conductivities of SZ7C3 coatings range from 0.4 to 0.6 W m−1 K−1 (significantly lower than those of 8YSZ). SZ7C3 coatings also exhibit moderate thermal expansion coefficients (TECs), near 10.8 × 10−6 K−1 at 1200 °C. The values of thermal expansion coefficients and fracture toughness are higher than those of La2(Zr0.7Ce0.3)2O7 (LZ7C3), which has been proposed as a promising high-temperature (> 1250 °C) TBC candidate material. The thermal cycling lifetime of SZ7C3/8YSZ DCL coating is much longer than that of LZ7C3/8YSZ TBC as demonstrated by the furnace thermal cycling tests, further confirming that SZ7C3 coatings have great potential as high-temperature TBCs for use in the next generation of advanced engines.
KeywordsDouble-ceramic-layer Sm2(Zr0.7Ce0.3)2O7 thermal barrier coating thermal cycling test thermo-physical properties
This work was financially supported by the National Natural Science Foundation of China (No. 51702244, No. 51501137), Natural Science Foundation of Hubei Province (No. 2017CFB285) and the Fundamental Research Funds for the Central Universities (WUT: 2018IVB037). Wenjia Song acknowledges the support of the ‘Freigeist’ Fellowship of the VolkswagenStiftung for ‘Volcanic Ash Deposition in Jet Engines’ (VADJEs, No 89705).
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