Novel High Sintering-Resistant Plasma-sprayed Thermal Barrier Coatings with Designed Large Two-dimensional Inter-lamellar Voids

Sintering of APS TBCs occurs during high temperature exposure. The sintering effect increases the stiffness and thermal conductivity. In this study, 2D inter-lamellar voids with large opening width were fabricated in La₂Zr₂O₇ (LZO) coatings through spraying LZO+SrO mixed powders following by dissolving the SrO splats in water. Microstructure evolution of the porous LZO coating at 1300°C was examined. Thermo-physic properties and the mechanical properties of the coatings were investigated. Results showed that 10 to 40% lamellar pores were developed in LZC coating corresponding to the SrO contents in LZO/SrO powders. These large 2D pores were survived from sintering at a high temperature of 1300^oC. Moreover, the thermal conductivity of LZO coating is maintained at a low level of about 0.6W/(m.^oC) after 100 hour exposure at 1300^oC. The present results show clearly that high sintering-resistance thermal barrier coatings can be achieved by designing inter-lamellar two-dimensional voids with large opening width.