Lu4Hf3O12 ceramics as potential top-coat materials for thermal/ environmental barrier coatings
Ceramics International(2023)
Abstract
The mismatch of thermal expansion coefficient (CTE) between thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs) is the key factor that affects the durability of T/EBCs in aero-engine environments. To alleviate the CTE mismatch, the novel TBC materials with relatively low CTE are needed. In this study, Lu4Hf3O12 with delta-phase rhombohedral structure was synthesized by solid-state reaction using Lu2O3 and HfO2 as the raw materials. Lu4Hf3O12 ceramics exhibited outstanding phase stability up to 1600 degrees C and comparable mechanical properties to 8 wt% Y2O3 stabilized ZrO2 (8YSZ) as well as great resistance against water-vapour/ oxygen corrosion. Additionally, it possessed the thermal conductivity of 1.20 W/m & sdot;K at 1000 degrees C, about 43% lower compared to traditional 8YSZ material (2.1-2.22 W/m & sdot;K), and coefficient of thermal expansion (CTE) of 8.46 x 10-6 K-1 (10.38 x 10-6 K-1 for 8YSZ). These results preliminarily reveal that Lu4Hf3O12 could be considered as a potential material for thermal insulation top-coat in the field of T/EBCs.
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Key words
Thermal/environmental barrier coatings,Phase stability,Thermo-physical properties
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