ZrO₂‐doped YTaO₄ as potential CMAS‐resistant materials for thermal barrier coatings application

Abstract

Thermal barrier coatings (TBCs) are applied on the critical components of gas turbine engine to insulate the thermal conduction and prolong the lifetime of metallic component. [1][2][3] Calcium-magnesium-alumino-silicates (CMAS) corrosion of TBCs has become more critical with the increase in engineoperating temperature. [4][5][6][7] CMAS arises from the volcanic ash, dust, and fine sand in the intake air, which will deposit on the surface of the TBCs during engine operation, finally form a CMAS melt when temperature exceeds the melting point, 1200°C-1250°C. 5,8 For the state-of-the art 7-8 wt% yttria stabilized zirconia (7-8YSZ) TBCs, CMAS melt could rapidly dissolve the YSZ and dispersively reprecipitate yttrialean zirconia at elevated temperature, which directly destroys the microstructural integrity of the top coat. 9,10 Additionally, CMAS melt, driven by the capillary force, 11 will fill the open pores of YSZ top coat at elevated temperature, and coagulate during cooling which severely stiffen the top coat and degrades the strain tolerance of TBCs. 7,[12][13][14] To mitigate the CMAS attack, one promising strategy is to develop new CMAS-resistant TBCs materials. 5 Generally, these materials should have high reactivity with CMAS melt. 5,15 The classical CMAS-resistant thermal barrier oxides are rare earth (RE) zirconates, e.g., RE 2 Zr 2 O 7 and RE 4 Zr 3 O 12 , [16][17][18][19] which can react with CMAS and rapidly precipitate a dense reaction products layer at the reaction front. The formation of dense reaction layer mitigates further CMAS infiltration, therefore exhibits a much better CMAS resistance in RE zirconates compared with 7-8YSZ.

CMAS Corrosion Resistance Behavior and Mechanism of Hf6Ta2O17 Ceramic as Potential Material for Thermal Barrier Coatings

“…Furthermore, the infiltration depth increases with time, and the infiltration rate decreases with time. The relationship between CMAS infiltration depth and corrosion time basically follows a parabolic law, which is due to the formation and growth of the dense layer [30]. Figure 8 shows a cross-sectional image of Hf6Ta2O17 ceramic corroded by CMAS at 1250 °C for 16 h and its corresponding EDS line scan.…”

“…The average thickness of the reaction layer La2(Zr0.7Ce0.3)2O7 is 140 µ m at 1300 °C for 4 h [17]. For 50 h CMAS exposure at 1300 °C, the CMAS infiltration depths of 17YSZ and Gd2Zr2O7 ceramics are 700 and 140 µ m, respectively [9,30].…”

“…Furthermore, the infiltration depth increases with time, and the infiltration rate decreases with time. The relationship between CMAS infiltration depth and corrosion time basically follows a parabolic law, which is due to the formation and growth of the dense layer [30]. After fitting the experimental data, the infiltration rate k at the three temperatures can be quantified in the form of a µm•t n , where a and n are constants and t is time.…”

Improved wear resistance and low thermal radiative conductivity of a middle‐entropy tantalate Y0.5Gd0.5Ta0.5Nb0.5O4

“…YTaO 4 is a potential TBC material, and there is still room for optimizing its properties 20,21 . Zheng et al.…”

“…19 YTaO 4 is a potential TBC material, and there is still room for optimizing its properties. 20,21 Zheng et al optimized the properties of YTaO 4 by doping Nb 5+ at the B site, and the lowest thermal conductivity was 1.57 W −1 m −1 K −1 . 22 Wu et al reported the properties of (Y 1−x Yb x )TaO 4 ceramics, and the phonon scattering intensity of (Y 1/2 Yb 1/2 )TaO 4 was maximum among these series ceramics.…”