Basic Performance Evaluation of Composite Perovskite Ba(Zn1/3Ta2/3)O3 Ceramic as Ceramic Coating Material for Thermal Barrier Coatings

Ba(Zn1/3Ta2/3)O-3 (BZT) ceramic was synthesized by a solid-state reaction method using BaCO3, ZnO, and Ta2O5 powders as the raw materials. The phase structure, high-temperature phase stability, thermal conductivity, coefficient of thermal expansion, and adaptability of spraying process of BZT were investigated and characterized, and compared with Ba(Mg1/3Ta2/3)O-3 (BMT), Ba(Ni1/3Ta2/3)O-3 (BNT), and Ba(Sr1/3Ta2/3)O-3 (BST) to evaluate the potential application of BZT as a top coating material for thermal barrier coatings. The results indicate that no phase transition occurs during the heating from room temperature to 1500 degrees C, and BZT is quite stable up to 1600 degrees C for 48 h, without the occurrence of decomposition, showing excellent high-temperature phase stability. The thermal conductivity of BZT is only 1.65 W center dot m(-1)center dot K-1 at 1200 degrees C, which is significantly lower than those of BMT (2.57 W center dot m(-1)center dot K-1), BNT (2.56 W center dot m(-1)center dot K-1) and BST (2.11 W center dot m(-1)center dot K-1), showing better high-temperature heat insulation ability. The average coefficient of thermal expansion of 11.3x10(-6) K-1 for BZT from 200 degrees C to 1400 degrees C is higher than these of BNT (10.7x10(-6) K-1) and BST (8.1x10(-6) K-1). The plasma-sprayed BZT coating has single perovskite structure, and the adhesion between the layers is compact for YSZ/BZT double-ceramic-layer coatings. Therefore, BZT ceramic might be a promising candidate material for novel thermal barrier coatings.