Evolution of microstructure and cyclic life of La2(Ce0.3Zr0.7)2O7-3 wt.%Y2O3 coatings

Abstract As a potential material applied for thermal barrier coatings (TBCs), the La 2 (Ce 0.3 Zr 0.7 ) 2 O 7 -3 wt.%Y 2 O 3 (3Y-LZ7C3) coating was deposited by electron beam physical vapor deposition (EB-PVD). To increase the service life of the coatings, the microstructures of the coatings were optimized by adjusting the deposition parameters. The deposition temperature of 930 °C and the rotation rate of 5, 15 and 25 rpm were selected. Due to the different driving forces, the microstructure of the column tips evolved from ‘roof tips’ to pyramids with increasing the rotation rate. There existed a {001} 〈100〉 sheet texture in the coatings deposited at 5, 15 and 25 rpm. In addition, the {001} 〈100〉 sheet texture in the coatings became weak with increasing rotation rate from 5 to 25 rpm. This indicated that the columnar crystals would be synergistically growing during the deposition process. The growth direction of the columnar crystals tended to be more uniform with reducing rotation rate from 25 to 5 rpm. Cyclic life of the coatings was tested at 1050 °C in a heat circulation furnace. The cyclic life tended to be prolonged by reducing the rotation rate from 25 to 5 rpm and the longest cyclic life was 350 h. This gives an approach to the improvement of the service life of TBCs by optimizing the microstructures.